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Home My WebLink AboutTRAB Staff Memo 10 11 16 Why Speed Limits? The setting of speed limits is fundamentally influenced by basic principles of human behavior. Research and experience have shown that effective speed limits are those that the majority of motorists will naturally and instinctively drive. Traffic laws that reflect the behavior of the majority of motorists are found to be the most successful. Common Misconceptions • Lowering the posted speed limit will slow down the traffic • Lowering the posted speed limit will increase safety and decrease the number of crashes • Raising the posted speed limit will increase the speed of traffic • Drivers will always travel at 5 mph over the speed limit which is posted What factors are considered when setting a speed limit? Nationally, the most recognized practice is to post the speed limit as near as practical to the speed at which 85% of the drivers are traveling. Most people choose a reasonable speed in which they feel comfortable and safe. Traffic engineers consider the 85th percentile speed to help determine the posted speed limit. The 85th percentile speed may be adjusted based on the following factors if they significantly impact roadway characteristics or safety: • Crash history • Roadway geometrics • Parking • Pedestrians and pedestrian crossings • Adjacent development • Traffic engineering judgment What a rational speed limit does: • Encourage compliance from the majority of drivers • Provide a clear reminder of the maximum reasonable speed under ideal conditions. When conditions change, drivers must reduce their speed accordingly • Serve as an effective tool for law enforcement • Minimize public antagonism toward law enforcement agencies which results from enforcement of artificially low speed limits • Provide a smooth and orderly flow of traffic to prevent crashes What is the relationship between vehicle speed and crashes? Roadways are safest when the majority of vehicles are traveling at about the same speed. Studies have shown that crash rates are at their lowest when traffic is travelling at or near the 85th percentile speed. Injury and fatality crashes are highest for motorists traveling at speeds much higher or lower than the 85th percentile speed or current flow of traffic. Variation of speed within the traffic stream creates more conflicts and passing maneuvers, which in turn lead to more crashes. Why not post a lower speed limit and have the police enforce it? This theory is only effective when law enforcement is present. The availability of police officers is limited for speed enforcement on a consistent basis. If unreasonably low speed limits are posted and not vigorously enforced, there will be varying speeds of traffic which will increase the potential for crashes. In general, setting unreasonable speed limits will also lead to a disregard to speed limits. Setting Appropriate Speed Limits on Wisconsin’s State Highways Speed limits are an important tool for promoting safety on streets and highways.Limits tell drivers what is the reasonable speed for a road section.They also help traffic enforcement by setting standards for what is an unsafe speed. The state sets speed limits for all roads.However, municipalities can change speed limits for roads under their authority,following guidelines in the Wisconsin Statutes.Selecting the appropriate speed limit can be a challenge because people often disagree.Residents frequently seek lower speeds,especially after a serious crash.Drivers tend to choose speeds that seem reason- able for the physical environment and that satisfy their personal needs,like saving time or seeking enjoyment. Local officials have a key role in setting limits.They must balance the competing concerns and opinions of drivers,residents and law enforcement agencies with statutory requirements and traffic safety. This booklet is designed to help.It includes back- ground information and research recommendations, summarizes statutory limits,describes the process for changing limits,and discusses signs,enforcement, advisory speeds,and other speed issues on local roads. This edition reflects updates from the 2009 Wisconsin Statewide Speed Management Guidelines. Background Speed-related vehicle accidents in Wisconsin from 2004 to 2008 accounted for 38%of all fatalities,30%of all injuries and 27%of all crashes. High speeds contribute to the severity of crashes.For example,85%of pedestrians struck by vehicles traveling 40 mph are likely to be killed while only 5%are likely to be killed when the speed is 20 mph. Common sense says that regulating speed is a good way to make streets and highways safer.As a result, citizens may demand lower speeds,especially if there has been a severe crash or a frightening “near miss.” However,driving behavior is not so easy to manage. A 1997 federal speed study shows that simply lowering speed limits has little effect on actual speeds,usually reducing speeds by only one-to-two miles per hour. The difference in speeds between vehicles traveling on the same road —a common cause of crashes —usually increases when speed limits are unreasonably low, making roadways less safe.Drivers generally choose their speed based on what they think is safe and reasonable for the conditions present.An unreasonable posted speed gets little consideration from drivers. An alternative for managing vehicle speeds is called “traffic calming.”This emphasizes physical changes to local streets—such as making them appear narrower or more restricted,adding speed bumps or traffic circles— so drivers consistently and voluntarily choose lower speeds that are both safe and comfortable. Philosophy Prevailing speed—the one most drivers choose —is a major consideration in setting speed limits.Engineers recommend setting limits at the 85th percentile speed, where 85%of freely flowing traffic travels at or below Setting Speed Limits on Local Roads Wisconsin Transportation Bulletin •No.21 1 that speed under ideal road conditions.The 85th per- centile method is considered the best way to represent what is “reasonable”and “proper”as perceived by the motorists.When 85%of drivers voluntarily comply with speed limits,it is possible and reasonable to enforce these limits. A recent study on Wisconsin roads compared crashes on roads with reasonable speed limits,or those accepted by the majority of drivers,with roads displaying posted speed limits considered unreasonable or irrational.The study showed that roads with reasonable speed limits had four times fewer crashes than roads with unreason- able speed limits.Other studies indicate the lowest risk of being in a crash occurs when a motorist travels at or near the 85th percentile speed.They also show that the 15%of motorists who exceed this limit cause many of the roadway crashes.These motorists are the most effective targets for enforcement. Research in this area emphasizes considering the road’s design speed in setting speed limits.Design speed is the highest safe speed for which the road was designed.It takes into account road type,road geometry and adjacent land use.Studies show that accident rates go down when speed limits are no less than 10 mph of the design speed.When the speed difference is greater,motorists choose a wider variety of speeds. This variance in speed between vehicles,more than the speed itself,results in higher crash rates. However,pedestrians,bicyclists and other road users may find the prevailing speed and design speed hazardous.Modern roads often are over-designed, particularly in residential areas where they empha- size the accommodation of functions like emergency vehicles or street parking.The resulting wide and unobstructed roads can encourage drivers to travel too fast for the safety of other road users.Simply setting lower speed limits is unlikely to produce the desired results,especially without effective enforcement.In these cases,authorities may wish to consider using some traffic calming techniques. Speeds should be consistent,safe,reasonable and enforceable.When 85%of drivers voluntarily comply with speed limits,it is possible and reasonable to enforce the limits with the 15%who drive too fast. Unreasonably low limits can promote disrespect for and disregard of other reasonable posted limits.They also promote a false sense of security among residents and pedestrians who may expect that posting lower limits will change driver behavior.Unreasonably high limits create unnecessary risks. 2 Fixed Limits –Statute 346.57(4)(a)Local Government Authority(b)–Statute 349.11(3)and (7)(a) 65 mph Freeway/Expressway WisDOT only 55 mph State Trunk Highways (STHs)WisDOT only 55 mph County Trunk Highways (CTHs),town roads Lower speed limit by 10 mph or less 45 mph Rustic roads Lower speed limit by 15 mph or less 35 mph Town road (1,000 ft min)with buildings on either side spaced an average of less than 150 ft apart Lower speed limit by 10 mph or less 25 mph Inside corporate limits of city or village (other than outlying district)Raise speed limit to 55 mph or less/Lower the speed limit by 10 mph or less 35 mph Outlying district (c)within city or village limits Raise speed limit to 55 mph or less/Lower the speed limit by 10 mph or less 35 mph Semi-urban district (d)outside corporate limits of a city or village Raise speed limit to 55 mph or less/Lower the speed limit by 10 mph or less 15 mph School zone,when conditions are met Raise speed limit to that of the roadway /Lower speed limit by 10 mph or less 15 mph School crossing,when conditions are met Raise speed limit to that of adjacent street /Lower speed limit by 10 mph or less 15 mph Pedestrian safety zone with public transit vehicle stopped No changes permitted 15 mph Alley Lower by 10 mph or less 15 mph Street or town road adjacent to a public park Lower by 10 mph or less Construction or maintenance zones,as appropriate (e)State and local agencies have authority to establish Notes: (a)Source:Updated 2007-2008 Wisconsin Statutes Database (b)All speed limit changes shall be based on a traffic engineering study,including modifications allowed under State Statute.Local governments can implement speed limit changes on the local road system without WisDOT approval when proposals are within the constraints identified above. (c)Per Statute 346.57(1)(ar)“outlying district”is an area contiguous to any highway within the corporate limits of a city or village where,on each side of the highway within 1,000 feet,buildings are spaced on average more than 200 feet apart. (d)Per Statute 346.57(1)(b)“semiurban district”is an area contiguous to any State or County highway where,on either or both sides of the highway within 1,000 feet, buildings are spaced on average less than 200 feet apart. (e)Guidance on establishing speed limits in work zones is available in http://dotnet/dtid_bho/extranet/manuals/tgm/13/13-05-06.pdf. Modified from original published in WisDOT Traffic Guidelines Manual,Chapter 13-5-1,Figure 1,June 2009. Speed limits and authority to change Authority Power to set speed limits rests with the state.Chapter 346.57 Speed Restrictions of the Wisconsin Statutes requires drivers to use a speed that is “reasonable and prudent,”to exercise “due care,”[346.57(2)]and to reduce speed under a variety of conditions such as “going around a curve...passing school children,high- way construction or maintenance workers...and when special hazard exists...”[346.57(3)]. The Statutes give fixed limits for more than a dozen situations depending on the road type,jurisdiction and land use [346.57 (4)(a-k)].See Table on page 2. Local or state officials have authority to change these limits within the limitations in Chapter 349.11, as summarized in the Table.They must conduct an engineering and traffic investigation to determine a reasonable and safe speed limit.The limit must then be legally adopted by the local authority and appropriate signs erected.When properly changed,such limits do not create additional liability.In addition,changes beyond those specified in the statutes are possible in consultation with and approval by the Wisconsin Department of Transportation (WisDOT). All limits,whether set by statute or local authority, are only effective and enforceable when official signs have been erected to give drivers adequate warning. Speeds also may be temporarily reduced in work zones where highways are being constructed, reconstructed,maintained or repaired [Ch.349.11(10)]. These changes must be properly posted and are not restricted by the other limitations in Chapter 349.11. A Transportation Information Center publication,Work Zone Safety:Guidelines for Construction,Maintenance and Utility Operations,describes correct work zone signing and set up. The local agency that maintains the roadway has jurisdiction for determining the speed limit.In most cases the responsibility is clear.If a roadway segment has joint jurisdiction,such as a road that borders two cities,then both agencies must agree on the speed limit.Obviously,the speed must be the same in both directions.In cases where the county or state maintains a road within the corporate limits of a city or village,the county or state is responsible for setting the speed limit. Coordination with local officials and law enforcement agencies is essential to set effective speed limits. Required studies Local authorities are required by the statutes to conduct engineering and traffic speed studies to modify all speed limits on local roads including those shown in the Table on the previous page.Engineering studies should include the following: 1)Measure and determine the 85th percentile speed, 50th percentile speed,design speed and pace speed. 2)Evaluate crash data for the past three to five years. 3)Document roadside development including land use,driveway locations,and school locations. 4)Document roadway geometrics including lane widths,shoulder width,sight distance limitations at hills,curves and intersections,plus parking, pedestrian and bicycle activity. 5)Determine the functional classification of the roadway and the practical function of the road within the state and local system. 6)Document the current speed limit and level of enforcement. A well-done traffic and engineering speed study requires a comprehensive effort by a trained profes- sional.Look for additional details in the 2009 Wisconsin Statewide Speed Management Guidelines report.Contact local law enforcement,County Traffic Safety Commissions,the WisDOT and consultants for assistance in conducting speed studies. Doing a speed study is time consuming but it is a necessary step for local agencies to legally modify speed limits.The effort also has the advantage of creating consistency in how enforceable speed limits are set across the state and increasing safety. Speed zone recommendations Local road authorities can initiate action to modify a speed limit and create a new speed zone on a local road.Citizens or other agencies also can request a change.Requests should be in writing and submitted to the local authority.The local agency should prepare a written response to the request describing their action and recommendations. Speed study recommendations for modifying a speed zone should accomplish the following: •Reduce the speed differential of vehicles •Be reasonable so a majority of motorists will comply •Reflect traffic engineering guidelines When making speed zone changes,do not base the decision on these reasons: •Noise complaints •Accommodate specialty vehicles •Correct spot safety problems •Future concerns that have not yet occurred Recommendations from a speed study generally fall within 5 mph of the 85th percentile speed.Factors that can alter this guideline include road function,access density,road geometry,parking,and pedestrian and bicycle activity.Using these secondary factors to 3 determine a recommended speed may require more law enforcement and result in increased crashes. Consider changing the road’s physical environment to lower speeds where possible. Speed zones should be at least 0.3 miles in length. Limit the number of speed limit changes along a route. Generally,it is advisable to change speed zones outside incorporated limits in 10 mph increments. Submit speed limit changes that require WisDOT approval to a WisDOT Regional office.Changes out- side the limitations outlined in Chapter 349.11 require department approval.Local governments take on liability when they make changes outside the outlined limitations without this approval. Post speed limit changes as soon as possible using flags or other means to call attention to the change. Monitor speed limit changes once they are made to identify any problems or need for further investigation. Proper signage A speed limit is not in effect until the area has been properly signed. Conversely,signs must not be installed until the limit has been approved and officially authorized. The Manual on Uniform Traffic Control Devices (MUTCD)governs signs.Two types may be used:one for passenger cars and another for special limits for trucks and buses. No more than three speed limits should be displayed on any one speed limit sign or assembly.Signs with special limits for trucks or other vehicles should include the word TRUCKS or a similar appropriate message. Display this below the standard message or on a separate plate that refers to SPEED or MPH. The standard speed limit sign must be 24 by 30 inches.Locate signs at: •Each point where the speed limit changes •Beyond major intersections •Other locations where it is necessary to remind motorists of the limit REDUCED SPEED AHEAD SIGNS also may be used to give advance warning of a lower speed zone. This sign should be used in rural areas to alert motorists when they need extra time to slow to the posted limit. Always follow it with a speed limit sign at the beginning of the new zone.Near schools,use the appropriate SPEED LIMIT sign after a school zone rather than the END OF SCHOOL ZONE sign. Enforcement Enforcement is critical.Without it,speed limits are not effective.When enforcement is increased considerably, violations and crashes have been reduced. Local officials should actively involve enforcement personnel in setting speed limits to ensure they are reasonably enforceable.Always inform enforcement agencies when changes are adopted. Enforcement requires wide public support.A first step is to ensure that the public perceives the speed limits as reasonable and fair because the voluntary cooperation of most drivers is essential.A second step is vigorous public information and education that stresses the safety benefits of enforcement.Make this a cooperative effort between highway and enforcement officials.Any infor- mation campaign should target specific aspects of the speeding problem such as young drivers,nighttime, school zones,work zones,or specific roads where potential traffic and pedestrian conflicts are high. Within law enforcement agencies,traffic enforcement does not compete well with criminal and drug enforce- ment.That means local highway officials must actively seek adequate agency enforcement.These efforts are most effective when the safety benefits are clear and there is strong support from local elected officials. Aggressive,targeted enforcement,combined with education,effectively produces better public compliance with traffic laws.The Federal High- way Administration recommends targeting enforcement programs to locations with a high incidence of crashes where speed was a contributing factor and to areas with high traffic volume. Long-term,low-intensity speed enforcement can produce meaningful results.Studies indicate some amount of the enforcement effort (15%is recommended) be directed to random locations and times.Stationary, marked patrol vehicles are most effective in creating longer-term enforcement benefits. 4 Minimum speed limits and slow moving vehicles Except on Interstate highways,there is no specific minimum speed on Wisconsin highways.However, statutes prohibit driving a motor vehicle “at a speed so slow as to impede the normal and reasonable move- ment of traffic,except when necessary for safe operation or to comply with the law.”[Section 346.59 Wis.Stats.] Vehicles that normally travel slower than 25 mph must display slow moving vehicle emblems.[Section 347.245 Wis.Stats.]In addition,the operator of a vehicle moving so slowly it impedes traffic must yield the roadway to overtaking vehicles,if practicable,when the operator of an overtaking vehicle gives an audible warning.[Section 346.59(2)Wis.Stats.] Advisory speed signs Advisory speed signs are used to tell drivers that a lower speed may be necessary at curves,turns,intersections and other localized conditions.These signs add emphasis and specific information to other warning signs,and recommend a comfortable and safe speed to drive in these locations.Do not confuse advisory speeds with enforceable speed limits.Advisory speeds do not imply the maximum operating speed at which skid and rollover occurs. The advisory speed must be determined by an accepted traffic engineering procedure but no ordinance is required.Maintenance or sign supervisors can erect the signs.They must be in accordance with guidelines in the MUTCD,2C-35. As with other traffic signs,advisory speeds should be consistent and reasonable to promote driver respect and compliance.This is not always the case. Research published by the national Transpor- tation Research Board (TRB)found that on the two-lane highways in the study,posted advisory speeds at most curves were well below prevailing traffic speed, and below speeds established using recommended devices and criteria. Advisory speeds are set based on average curve speeds for different angles of deflection.One device widely used for establishing advisory speeds on curves is the ball bank indicator.Relatively inexpensive,this curved level is mounted in an engineer ’s car.The engineer makes successive trial runs through a curve, taking care to drive parallel to the centerline of the curve,increasing speed by 5 mph each time.The indicator shows the angle of deflection in degrees. The TRB study reports that the generally accepted criteria,based on tests conducted in the 1930s,produce unrealistically low speeds with modern cars and should be revised upwards.The authors say ball bank readings of 12 degrees above 40 mph,16 degrees between 30 and 40,and 20 degrees below 30 would better reflect average curve speeds. Ball bank readings tend to fluctuate rather widely during a trial run and can be affected by loose-surfaced roads and vehicle suspension systems.As a result,setting a recommended speed depends to a significant extent on the judgment and experience of the person making the tests.The recommended speed should feel comfortable for the average driver and be lower than the maximum safe speed.It should also be sensible in comparison with prevailing speeds. Summary Establishing and enforcing reasonable and safe speed limits is the responsibility of local officials.This often includes balancing conflicting issues of safety,traffic movement,and community concerns. Coordination with local law enforcement is vital to effective speed control.Most speed zones should encourage voluntary compliance by using reasonable speed limits.Traffic calming techniques that involve physical and perceptual changes also can help. Consulting enforcement officials when determining effective limits is important and they can help work with the community in difficult areas. The traffic engineering staff of WisDOT also is a good resource.Since they participate on county Traffic Safety Commissions,this is an easy way to contact them for assistance. Several sample speed limit ordinances are shown on page 6. 5 6 Sample amendmenttoaspeedordinance AMENDING CHAPTER 1 OF THEBADGERCOUNTYCODEOFORDINANCESSPEEDLIMITCHANGES The County Board of Supervisors of the County of Badger does ordain as follows:ARTICLE 1.Unless otherwise expressly stated herein, all references to section and chapter numbers are to those of the Badger County Code of Ordinances.ARTICLE 2.Section(2)(b)(2)is created to read as follows:1)Chestnut Road,City of Centerton.Twenty-ﬁve miles per hour from its intersection with USH 51 to its intersection with Winona Drive. “B a d g e r C o u n t y ”t ra f ﬁ c o r d i n a n c e S P E E D LI M I T S.(1)T he p r ovision of se c t i on s 3 4 6 .5 7 &346.59 o f t h e W i s co nsi n S t a t ute s,r elat i ng t o t h e m a xim um a n d m i nim um sp e ed of ve h i c le s,a re he r eby a d o p t ed a s par t of th is s ec t i o n as is fu lly s e t for t h h e re i n,exce p t a s sp e c iﬁ ed by se c t i o n 2 o f th i s o r d in a nce,p u r s uan t t o s e c t i o n 3 4 9 .1 1 (3)(c ) o f t he W i s c o ns in St a t ute s .(2)N o v eh icl e s hall e x ce e d n ot ed s p ee d l im i t s on t he f o l l o w i ng c o un t y t ru nk hi g h w ay s : (a )Co un t y Tru n k Hi g hw ay “A” (1)U n i n cor p or a t e d V i lla ge o f E ste sv i l le,To w n of T er r y .T hi r t y -ﬁve mil e s p er h o ur f r o m i t s j un c t i o n w i t h S TH 7 8 ,in Este s v i l le,so u t hw este r l y 0.35 mi l es. (2 )C i ty o f Co vin gto n ,To w n of Yo rk.T hi r t y -ﬁve m i le s p e r hou r from i t s i nte r s ec t i o n w i t h CT H “N ” (Vete ran s Dr i v e),e a ste r l y to a po in t 0 .1 5 m ile s e a s t o f its in t e rs ec t io n w ith R a c e Tr a c k Ro a d. (b )Co un t y Tru n k Hi g hw ay “A B ” (1 )Town o f Fi nis.T hi r t y mil e s p e r h o ur f r o m t he br i d ge ov er th e Ya h a r a R i ve r l o c a t ed o n a l i n e c om m o n to s e c t i o ns 1 3 a nd 1 4,Town of Fi n is, s ou t h we s t e r ly t o U S H 5 1 . (2 )C he st nu t Roa d,C i t y o f Cen t er t o n.T hi r t y mi l e s p e r h ou r from t he i nte r s ec t i o n o f U SH 5 1 ,eas te r l y t o D ro s t er R oad. References Wisconsin Statewide Speed Management Guidelines, WisDOT,June 2009 Speed Management Safety,FHWA resource website at http://safety.fhwa.dot.gov/speedmgt/ Evaluation of Criteria for Setting Advisory Speed on Curves,Mashrur A.Chowdhury,Davey L.Warren, Howard Bissell,&Sunil Taori,Transportation Research Board Paper No.980133,January 11-15,1998,21 pp. Factors Affecting Speed Variance and Its Influence on Accidents,Nicholas J.Garber &Ravi Gadiraju, Transportation Research Record 1213,Transportation Research Board,1998,10 pp. A Policy on Geometric Design of Highways and Streets,AASHTO,2004,pp 66-72. Spot Speed Studies,Ch.3 of Manual of Transportation Engineering Studies,Institute of Transportation Engi- neers,H.Douglas Robertson,Ed.,2000,pp 33-51. Sample speed limit ordinances Local boards of elected officials must adopt speed limits in ordinance form. Here are sample ordinances for county and municipal governments.Local ordinances also may include details on forfeitures and law enforcement authority.The ordinance should be reviewed by the agency’s attorney. SPEEDSPEEDLIMITLIMIT REDUCEDREDUCEDSPEEDSPEED REDUCEDREDUCEDSPEEDSPEEDAHEADAHEAD SPEEDSPEEDZONEZONEAHEAAHEADD Sample municipal ordinance Section 3.SPEED LIMITS. [Towns, Cities, and Villages] The _____________ [Council or Village Board]hereby determines that the statutory speed limits on the following streets or portions thereof are unreasonable, unsafe and imprudent and modiﬁes such speed limits as follows: (1)SPEED LIMITS INCREASED. Speed limits are increased as follows upon the following designated streets or portions thereof: (a)Outlying Districts 45miles per hour on __________________Avenue between ____________________________ Street andthe __________________ [City or Village]limits; (2)SPEED LIMITS DECREASED. With the approval of the Wisconsin Department of Transportation, the speed limits are decreased as hereinafter set forth upon the following highways or portions thereof: (a)Semi-Urban Districts 25 miles per hour on _________________Road between County Trunk ________________and the______________ [City or Village]Limits; 30 miles per hour on ________________Road between County Trunk ___________an d the limits Revised 12/2009 ©Wisconsin Transportation Information Center (TIC).Wisconsin Transportation Bulletin is a series of fact sheets with information for local town, municipal and county officials on street and highway design,construction,maintenance,and management.WTB fact sheets are produced and distributed by the Wisconsin Transportation Information Center LTAP,a project of the University of Wisconsin-Madison,Department of Engineering Professional Development,funded by the Federal Highway Administration and the Wisconsin Department of Transportation.UW-Madison provides equal opportunities in employment and programming, including Title IX requirements. Download at http://tic.engr.wisc.edu.Limited print copies available free from the Wisconsin Transportation Information Center,UW-Madison,Department of Engineering Professional Development,432 North Lake St,Madison,WI 53706-1498.TEL 800.442.4615 FAX 608.263.3160 E-MAIL tic@epd.engr.wisc.edu. http://tic.engr.wisc.edu WISCONSIN TRANSPORTATION INFORMATION CENTER –LTAP at theUniversity of Wisconsin–Madison SPEEDING isamajorsafety problemonWisconsin’slocaland stateroads.Butsimplylowering speedlimitsisnottheanswer andsettingthemtoolowusually makestheproblemworse.Itis betterto getthefacts through aspeedstudy,thenusetheinfor- mationtosetandenforcesafe andrationalspeeds. Astrongpartnershipbetween localhighwayandstreetdepart- mentsandlocallawenforcement iscriticalforthistowork.New StatewideSpeedManagement Guidelines,recentlyreleasedby theWisconsinDepartmentof Transportation(seestorypage3), presentabestpracticesapproach —includingadetailedreviewof methodsforconductingeffective speedstudies—thatbothgroups canusetoaddressthequestionof whethertoraiseorlowerexisting speedlimits. Wisconsinstatutesrequirethat localgovernmentsbaseallspeed limitchangesonatrafficengineer- ingstudy.Suchacomprehensive studyincorporatesspeedstudy datawithcrashstatisticsandinfor- mationonroaddesign,signage andotherroadwaycharacteristics. Datafromaspeedstudyis valuableonmanylevels.Itprovides locallawenforcementwithfacts theycanapplytoimprovingeffec- tiveuseofpatrolresources.Road andstreetofficialsgainknowledge aboutspeedandsafetyproblems. Andtrafficengineershaveatimely snapshotofissuesthataffect maintenanceanddesignprojects. Representativesfromlocal governmentsacrossthestate 2 IDEAEXCHANGE Sprayertruckdoes doubleduty 3Statereleases speedmanagement guidelines 4Stricterdieselemission rulesaffecttruck replacements 4TICresourcesstretch trainingbudgets 7 RESOURCES 8 CALENDAR Wisconsin statutesrequire thatlocal governments baseallspeed limitchangeson atraffic engineering study. Speedstudiesstrengthenlocalpartnershipsforsafety INSIDE Continuesonpage6 FALL2009 attendedspeedmanagement workshopsinMaytolearn abouttheguidelines.Inthis article,severalparticipants describehowtheyusespeed studies. Perceivedsafespeeds Peopletendtotravelatspeeds thatfeelcomfortableandsafe regardlessofpostedlimits.They judgetheirabilitytodrivesafely byfactorslikethephysicaldesign oftheroadway,howwellthey knowtheroute,trafficvolume andvisualcueslikeparked vehiclesorseeingapatrolcar. Speedsperceivedbymotorists asreasonableoftenexceedthe statutoryorpostedlimits.Referred tobyexpertsasthe“safeand rationalspeed,”the85thper- centileisthespeedatorbelow which85percentofdriverstravel. MonroeCountyHighway CommissionerJackDittmar, Hudson PoliceChiefMartyJensen and OperationsLieutenantFrank FentonfromtheCityofMonona PoliceDepartment,alluse85th percentilespeedsasaguidefor proposingarevisedspeedlimitor enforcementactivity. ChiefJensenconsidersevaluat- ingstudyinformationbasedon the85thpercentileawakeupcall forcommunitiestoreducetheir toleranceforspeedingandrethink theirapproachtoenforcement andtrafficplanning. Factstrumpguesswork TheMononaPoliceDepartment usesapost-mountedradar recordertogatherinformation onspeedtrendstheyfactorinto thefocusedenforcementthatis centraltotrafficcontroloperations intheDaneCountycommunity. “Technologykeepsusfrom guessingabouthowtodeploy resources,”explainsLieutenant Fenton.“Withactualdata,our actionsarenotarbitrary,but rootedinfact.” Positionedlargelyoutofsight andfunctionalyear-round,Fenton saysthedevicedetectsallvehicles passinginbothdirections.It recordsthenumberofvehicles, vehiclelength,speedsandtime ofday.Officersdownloadthedata totheirhand-heldorlaptopcom- putersviaawirelessconnection, thentransferitintoaspreadsheet programtoanalyzeandorganize. “Wemovethetrackingdevice aroundtotestforaproblem whentherearecomplaintsorpick Trafficstopsarepartofafocused enforcementstrategyforthe MononaPoliceDepartment. FALL20092 UNIVERSITY OF WISCONSIN–MADISON WISCONSIN Sprayertruckdoesdoubleduty TAKEONE tankertruckwith sprayer.Addtwocountyhighway departmentsandmixinagood measureofcooperationand sharedinterest.Theresultisan efficientreturnoninvestmentfor onecounty,andaneconomical waytotestasnowandice applicationforanother. JeffersonandWaukeshacoun- tiesinitiatedanequipmentsharing agreementtwoyearsagothat keepsJeffersonCounty’ssprayer truckbusyyearround.Jefferson Countywasusingthe2500-gallon tankertruckexclusivelyduring thesummermonthsfordust controlandtoaddwatertobase materialstooptimzemoisture contentforcompactiononroad reconstructionorrehabilitation. NeighboringWaukeshaCounty wantedtotestanti-icingmethods onthestateandcountyroads itmaintainsinwinterbefore committingtightbudgetdollars toamajorcapitalpurchase.Fleet ManagerRobertRauchlesearched toseeifotheragencieshad equipmentthecountycouldrent foranaffordabletrialrun.He Payingthestaterate Underthetanksprayeragreement, WaukeshaCountytakesposses- sionofthetruckfromaboutmid- Octoberthroughmid-April.They modifyitslightlytoaccommodate nozzlesforsprayingasaltbrine mixture.Sofar,theanti-icing operationisproducingtheresults thecountywasafter. JeffersonCountycurrentlydoes anti-icingonbridgedeckswith asmallertruckandspraytank thatCoonensays“getsaround quicker.” WaukeshaCountypays JeffersonCountythestandard StateHighwayMaintenance ClassifiedEquipmentRatefor useofthetanksprayer,thesame ratethestateusestoreimburse countiesformaintainingstate roads.JeffersonCountycarries liabilitycoverageontheequip- mentthroughitsparticipation inthestate-administeredLocal GovernmentPropertyInsurance Fundthatextendstoitsuseby anotheragency.Eachdepartment handlesmaintenanceonthetruck andsprayerequipmentduringthe monthstheyuseit. Communication akeyingredient Theequipmentexchangebetween JeffersonandWaukeshacounties demonstrateshowcloserlocal governmenttiesbenefiteveryone. Rauchlenotesthattheemphasis thesedaysonbetteremergency preparednessandmutualaidhas improvedcommunicationscounty- to-countyandbetweencities, townsandvillages. Astheyshareinformationand resourcesformanaginglocal roads,publicworksandhighway departmentscantestnewideas andmakecapitalinvestmentsin spiteofatightbottomline. foundwhatheneededrightnext door—JeffersonCounty’struck sprayersittingidleduringthe wintermonths.Rauchlegotin touchandthetwocountiesset upaleaseagreementhedescribes asawinforbothsides. “Allofusarelookingforways tospendbudgetdollarsmore efficiently,”Rauchlesays.“Equip- mentpurchasesarenecessary majorcosts,sowherewecan comeupwithalternativesthat work,it’sabonus.” Useitorloseit ThebonusforJeffersonCounty wasgeneratingwelcomerevenue fromunderusedequipment.Fleet ManagerErikCoonensaysputting billablehoursontheequipment helpsjustifykeepingitorreplacing itwhenthetimecomes.Coonen inheritedtheagreementwith WaukeshaCountywhenhejoined thedepartmentearlierthisyear andconsidersitapositiveexample ofmakingusefulequipmentpay foritself. Bothfleetmanagersciteother sharingorcontractingagreements thathelpthemgetthingsdoneor keepequipmentprofitablyin action.JeffersonCountyrecently contractedwithDodgeCountyfor roadstripingandtheyroutinely sendtheirchipspreader,an operatorandsuppliesofchipsto othernearbycountiesforroad projects.And,whenCoonen’s roadsweeperwasoutofcommis- sionthissummer,hesurveyedthe listofcountiesJeffersonCounty cooperateswithtolocateafillin. ColumbiaCountyhadonehe couldleaseonashort-termbasis. Ittakesplanningandnegotia- tiontosetupagreementsthat suitbothparties,Rauchlesays. Heislookingforadditional opportunitiestocooperatewith otheragenciesonequipment leaseorpurchase. “Equipment purchasesare necessarymajor costs,sowhere wecancomeup withalternatives thatwork,it’sa bonus.” EXCHANGE Idea Contact ErikCoonen JeffersonCounty HighwayDepartment 920-674-7390 erikc@co.jefferson.wi.us BobRauchle WaukeshaCounty Departmentof PublicWorks 262-548-7724 brauchle@ waukeshacounty.gov JeffersonCounty'ssprayertruckworksroadprojectsduring thesummermonths,addingmoisturetobasematerials. FALL2009 3 UNIVERSITY OF WISCONSIN–MADISON WISCONSIN Statereleasesnewguidelinesforspeedmanagement RECENTRELEASE ofthenew StatewideSpeedManagement Guidelines bytheWisconsin DepartmentofTransportation BureauofHighwayOperations givestransportationofficials aroundWisconsinstep-by-step recommendationsforstudying andsettingsafe,enforceable speedlimits. Theguidelinesreviewfactors relatedtotrafficspeedthatinflu- enceroadsafety,suchaspublic policyandratesofcompliance withexistinglimits.Thepublica- tion’smainfocusisadetailedlook attheprocessofconductingan effectivespeedstudyandusing thefindingstoestablishormodify aspeedzone.Itisimportantto notetheguidelinesarearesource, notamandate.Butstatestatutes requireofficialstoconductaspeed studybeforethereisachangein speedlimit. Askingforinput WisDOTtrafficengineersdevel- opedtheguidelinesinresponse togoalsoutlinedintheWisconsin StrategicHighwaySafetyPlan 2006-2008.Theauthorsreviewed currentstatestatutesgoverning fixedspeedlimitsandmodifica- tionstothoselimitsondifferent roadconfigurations.Theylooked atcrashdatafindingsfromthe TOPS(TrafficOperationsand Safety)LabattheUniversityof Wisconsin,andresearchedstudies donenationallyondefiningand settingrationalspeeds. Theyalsoaskedforinput.Wis- DOTStateTrafficSafetyEngineer RebeccaSzymkowskiandDerek Hungness,atransportationplan- nerwithSRFConsultingGroup whocollaboratedontheproject, previewedtheguidelinesata speedmanagementsummitearlier thisyearandduringaseriesof statewideworkshopsco-sponsored bytheTransportationInformation Center. Szymkowskisaystheoutreach effortsgeneratedgooddiscussions abouttheissueslocallawenforce- mentandelectedofficialsface whenmanagingspeedissuesin theirjurisdictions.“Hearingfirst- handhowthingslikechanging landuseandresidentcomplaints figureintodecisionshelpedus understandtheiruniqueneeds whenitcomestospeedmanage- ment,”shesays.“Inreturn,I feelthepeoplewhoparticipated walkedawaymoreknowledgeable abouthowtorespondwithfact- basedstrategies.” Bestpracticesthat makesense The“bestpractices”coveredin theguidelineshadtomakesense forlocalgovernments,Hungness notes.“Wedevelopedadata- drivenapproacheveryonecanuse toevaluateexistingspeedsand followanorderlyspeedstudy processwhentheywanttomake achange.” Theguidelinesdiscussthe conceptof85thpercentilespeed, “thespeedatorbelowwhich85 percentoftheobservedtraffic travels.”Transportationengineers andotherexpertsconsiderthe 85thpercentileasafeandrational speed,andinformationcentral toaspeedstudy.Stateandlocal officialsmustusethismeasure- mentwhenevaluatingrequests tomodifyaspeedlimit. Thepublicationalsodefinesthe significanceofdesignspeed,speed distribution,secondaryroadway attributesandotherrelevantdata. Onesectionfeaturesacomparison ofdatacollectionmethods,every- thingfromradarrecorderstoa stopwatch.Szymkowskisays feedbackfromtheworkshops persuadedthemtoincludea widerrangeofmethodsthatgive localgovernmentsmoreoptions. Localgovernmentsalsowill findaspeedstudyreportinthe guidelinesandanExcelworksheet. Userssimplyenterspeeddata fromtheirstudyandtheprogram producesthenecessaryanalysis. Uniformapproach Thegoalwastocreateauniform andconsistentapproachtospeed managementacrossthestate.The guidelinesserveasatemplatefor gatheringandanalyzingdatathat stateandlocalofficialscanuse todeterminewhethertomodify limitsortakeotherstepsto improveroadsafety. “Whenwesetspeedsthatare appropriate,driversandpassengers feelsaferontheroads,”observes Szymkowski.“Theguidelinesbring alltheelementstogetherinone placefordoingthis.” Sheaddsthatheroffice,the TrafficEngineeringSectionof theState’sBureauofHighway Operations,isavailableasa resourcetolocalgovernments iftheyneedhelpapplyingthe guidelines. Guidelinesandworksheetare availablebycontactingSzymkowski at608-266-9381or rebecca. szymkowski@dot.wi.us,orvia downloadfromtheWisDOTand TICwebsites. Contacts RebeccaSzymkowski WisDOT 608-266-9381 Rebecca.Szymkowski@ dot.wi.gov DerekHungness SRFConsultingGroup 608-829-0010 dhungness@srfconsulting.com Resource SettingSpeedLimits onLocalRoads TICBulletin#21.Updatedin 2009toincludeinformation fromnew StatewideSpeed ManagementGuidelines. Reviewsroleoflocal governmentsinsetting limitsandcoversabroad rangeofrelevantspeed issues.Gotothepublications linkat http://tic.engr.wisc.edu/ toorderordownload. Thegoalwas tocreatea uniformand consistent approach tospeed management acrossthe state. 35 MPH SPEED ZONE AHEAD 4 FALL20094 UNIVERSITY OF WISCONSIN–MADISON WISCONSIN Stricterdieselemissionrulesaffecttruckreplacements LOCALHIGHWAY andpublic worksdepartmentspreparingto replacedieseltrucksintheirfleets musttakethenextgenerationof cleandieselenginesintoconsider- ation.The2010modelyeartrucks mustimproveontheengines introducedin2007tocomplywith strictercleandieselstandardsset bytheEnvironmentalProtection Agency(EPA)eightyearsago. Truckssoldsince2007feature catalyticexhaustemissioncontrol devicesthatsubstantiallyreduce theemissionofnitrogenoxide (NOx),particulatematterand othertoxicgases.TheEPArequires additionalreductionsindiesel emissionsin2010modelsand on-boarddiagnosticstomonitor whereitmixeswithincomingair, aprocessthatlowersthecombus- tiontemperatureandlimitsthe productionofpollutingemissions. SCRincorporatesanafter- treatmentsystemthatreduces NOxlevelsbyinjectingdiesel exhaustfluid(DEF)intothe exhaust.DEFisablendofurea anddeionizedwaterthatcom- bineswiththeengineexhaust toformnitrogengasandwater. DEFisnontoxicbutitiscorrosive tounpaintedaluminum. Additionalmaintenanceon SCR-equippedtrucksinvolves managingaDEFsupplyandtrain- ingdriverstokeepthefluidat adequatelevelssotheenginedoes notpowerdownunexpectedly. theeffectivenessofthecontrols. EPAprojectsareductionofNOx emissionsof2.6milliontonsby 2030whenexistingfleetsare completelyreplaced. Exhaustsystemoptions Allmanufacturersareintroducing systemsthatmeetthe2010 requirements.Someareimproving oncurrenttechnologywithan AdvancedEGR(exhaustgas recirculation)system.Othersare adoptingSCR(selectivecatalytic reduction)intheirdieseltrucks,a newertechnologycurrentlyused invehiclefleetsinEurope. AdvancedEGRcirculatesa higherpercentageofexhaust gasesbacktotheenginecylinders REGULARTRAINING sustains goodperformance,productivity andsafetyonthejob.Evenwhen budgetsaretight,localhighway andstreetdepartmentsfindaway. TheTransportationInformation Center(TIC)on-siteworkshops andlendinglibraryaretwolow- cost,flexibleresourcesavailableto localgovernmentswhowantto stretchtheirtrainingdollars. On-siteworkshops TIC’sflexibleon-siteprograming letsdepartmentsschedulework- shopsfortheirownworkersoras jointprogramswithotheragencies foronly$800.Localagenciescan workwithTICinstructorstotailor abasiccoursetoaddressspecific issuesinaformatthatbenefitsthe mostpeopleatonetime. TheprogramForestCounty HighwayCommissionerJohn RogersputtogetherlastMayisa goodexample.Rogersorganizeda customizedTIC WorkZoneand FlaggerSafety on-siteworkshopto providepartofanannual“Dayof Safety”hisdepartmentregularly co-hostswiththreeothercounties andarangeofothertopicspro- ducedbytransportationtechnology centers,highwayagencies,equip- mentcompaniesandothersources. BevHanefeld,ProgramAssistant intheFondduLacCountyHigh- wayDepartmentsaysheragency usestapesfromTICforsafetytrain- ingdaysheldinfallandspring. Theprogramscombinethetaped presentationsontopicslikewinter maintenanceandsnowplowing, workzoneoperationsandvegeta- tionintheright-of-waywitha question/answerperiod.Hanefeld callstheprogramsanaffordable resourcethathelpsdriversand mechanicskeeptheirskillssharp. TheCityofAntigoPublicWorks Departmentdoesabigpushin springandfalltotrainnewpeople andgiveothersarefreshercourse. SafetyandProgramCoordinator JulieZacksaysthetrainingtapes fromtheTIClibrarystretchthe budgetandgivethedepartment flexibilitytoschedulegroupses- sionswhentheyanticipatedown time.“Gladit’soutthere,“Zack says.“Wetakeadvantageofevery resourcethat’slowcostorfreeto keeppeopletrainedandready.“ Manufacturerstalk aboutfueleconomy inmilespergallon, astatisticthatis irrelevantfor agenciesthat measuretruckuse byenginehours notmiles. TICresourcesstretchtrainingbudgets Feeincrease TICwillcharge$60for itsregularlyscheduled workshopsbeginning January1,2010.Thefee increasehelpsmaintain thequalityandreachof theworkshops,presented inmultiplelocations aroundthestateon topicsofcurrentinterest. Thisisthefirstincrease since2002. Regulartraining programssustain goodperformance, productivityand safetyonthejob. andthreelocalcommunities.The sevenagenciessplitcoststocreate astrongeducational programforabout80people. “Wewantedtoaddresssafe flaggingoperationsfortheroad crewsandTICwastheonlyplace withaprogramthatfitour needs,”recallsRogers. TheOneidaCountyHighway Departmentbookeda Basic Surveying workshopwithTIClast year.Thedepartmenthadlittle previoustrainingsettingelevations forculvertsandditches,says PatrolSuperintendentFreeman Bennett.“Ithelpstohavethe wholecrewonthesamewave- lengthandthat’swhatthework- shopaccomplished.” Lendinglibrary TICprovidesanothertraining resourceinitslendinglibrary— freetolocalgovernmentsand highwayagenciesinWisconsin andotherswhoprovidethemwith contractandprofessionalservices. ThelibraryfeaturesDVDs,CDs andvideotapesonroadconstruc- tion,maintenance,safetyissues FALL2009 5 UNIVERSITY OF WISCONSIN–MADISON WISCONSIN AdvancedEGRshouldtakeless trainingtooperateanddoesnot requireDEF. Performanceremains greatunknown Itistoosoontellhowtheupgraded systemswillperforminpublicworks andhighwaymaintenancetrucks. Industryreportsgenerallyindicate SCRwillhavetheadvantageover EGRinfueleconomybuttheaddi- tionalcostforDEFmayreduceor cancelouttheoperationalsavings. T.J.Sorensen,EquipmentSuper- intendentfortheGreenBayDepart- mentofPublicWorks,notesthat manufacturerstalkaboutfuel economyinmilespergallon.This statisticisirrelevantforagencies thatmeasuretruckusebyengine hoursnotmiles,hesays.The Contacts T.J.Sorensen GreenBayDepartment ofPublicWorks 920-492-3751 tjso@ci.green-bay.wi.us TomSchuh MonroeTruckEquipment 608-329-8158 tschuh@monroetruck.com Resource http://www.epa.gov/otaq/ diesel/index.htm EnvironmentalProtection Agencysitewithinforma- tionaboutthecleandiesel campaign,andlinksto updatesonthenewrules andrelatedfinancing programs. “Weencourage peopletoanticipate futureneedsso whentheyhavethe budgettoadd equipmenttwoor threeyearsfrom now,thevehicle theyowniseasy tomodifyasecond time.” WisconsinChapterofAPWA (AmericanPublicWorksAssocia- tion)andothershaveaskedtruck andenginemanufacturersto comeupwithmoreusefulfuel- savinginformation. Sorensenisrequestingbidsnow ontrucksequippedwithAdvanced EGR,SCRandthecurrenttechnol- ogysohecandoaside-by-side comparisonforhis2010truck replacements.(Localagenciescan contacthimforhisspecifications.) WhileSorensenknowstheolder technologyischeaper,hewantsto seethecostdifferentialforhimself todetermineifEGRorSCRoffer advantagesthatmakethemworth payingmore.“I’dalsoliketostudy whatotheragencieslearnfrom runningthesesystems.” Recentpriceinformationfrom truckandenginemanufacturers indicatesthe2010requirements mayaddfrom$6000to$8000 morepertruck. Withtwotrucksinoperation thatmeet2007emissionstan- dards,Sorensenknowseducating driversisessentialtoavoidcostly repairsanddowntimeonthe newersystems.Dieselparticulate filtersrequireregeneration,for example,torunefficiently. Lessleewayfornew vehiclesetups Acriticalissueforfleetsisupfitting newtrucksforpublicworksor highwaydepartmentuse.Upfitters needtocoordinatethelocationof thenewemissionsequipmentand exhaustonthechassiscaband framerailstomountdumpbodies, underbodyplows,frontdischarge spreaderswithcrossconveyors anti-icingtanksorothermainte- nanceequipment. TomSchuhisShopSuperinten- dentfortheTruckEquipment DivisionofMonroeTruckEquip- mentbasedinMonroe,Wisconsin. Thecompanyhandlesupfitting formanystateandlocaldepart- ments.Schuhsaysalthough everynewmodelyearposesa challenge,designsforthelatest compliantexhaustsystemsprovide lessleewayformodification.In spiteofthis,heisconfidentabout meetingallupfittingrequests,in partbecauseeachmanufacturer offersmorethanoneconfigura- tionoftheemissionsequipment andexhaustsystem.Customers choosetheconfigurationthat accommodatestheequipment theywilladd. “Itcallsformoreplanning aheadthanusual,”Schuhsays. “Weencouragepeopletoantici- patefutureneedssowhenthey havethebudgettoaddequip- menttwoorthreeyearsfrom now,thevehicletheyownis easytomodifyasecondtime.” Schuhreportsmostofhisbig customers,statesandlarge counties,arefollowingthe changesandhavemoreexamples ofthenewtechnologyintheir fleets.Heagreesfueleconomy remainsaconcernforeveryone. Smallerlocalgovernmentswho useMonroeTruckforupfitting havelessexperiencewiththe newequipment.Schuhsaysthey generallygeteducatedwhenthey startthebidprocessorcontact himaboutmodifications. Earlyadoptersaresource Equipmentmanagersneedto considertheiroptionswhenit comestocurrentvehiclereplace- mentstrategies.Theycanwork withsupplierstolocatetruckswith 2007engines,delaypurchaseto learnfromtheexperienceofearly adoptersorevaluatethecostof rebuildingexistingequipment.In eachcase,theirgoalistohave trucksthatdothejobandareeasy tomaintainatareasonablecost. Crossroads willcontinueto followthistopic.Weinvitelocal roadofficialsinWisconsinwho havethenewestcleandieseltech- nologyinusetocontactusand sharetheirexperiences. Worthwhileinvestment Agencycommitmenttotraining isimportant,saysDaveWepking, SafetyandTrainingCoordinator fortheCityofWestAllis.“When topmanagementpromotesthe conceptasaworthwhileinvest- ment,there’smoreofanexpecta- tionamongemployeesthattrain- ingwillhappen.” Besideseducatingemployees onequipmentmaintenanceand operation,scheduledtraining helpsthecitydecreaseliability forequipmentorproperty damage—importantduringa budgetcrunch. TheWestAllisDepartmentof PublicWorksusesvendortrain- ing,TIClibraryresourcesand otherapproaches,likehaving experiencedoperatorstrainnew recruits.Qualitytrainingisthe goal,Wepkingsays,toestablish thebasicsandmakesafeopera- tionsecondnaturetopeople. ContactTICat800-442-4615 or tic@epd.engr.wisc.edu tolearn moreabouton-siteworkshops. Findthevideocatalogonlineat http://tic.engr.wisc.edu/. NOx NOx NOx NOx NOx FALL20096 UNIVERSITY OF WISCONSIN–MADISON WISCONSIN Speedstudies strengthenlocal partnershipsfor safety continuedfrompage1 “Themorewe documenttravel conditionsonour roads,theeasier itwillbetoaddress questionsabout safespeedsand comeupwith effectivesolutions.” troublespotsforrandomtesting,” Fentonnotes.“Thereadingshelp usdetermineifthereisagenuine speedingissueornot.” Mononaiscreatingapanelof citizensandelectedofficialsto reviewneighborhoodspeedcom- plaints.Theywillexaminespeed studydata,weighdifferentsolu- tionsandrecommendappropriate action.Fentonsaysitisawaythe communitycanworktogetheron trafficsafetyissues. Enforcingsafespeedsin Mononainvolvesmultipleofficers monitoringtrafficalongaspecific stretchofroadorstreetand pullingspeedersover.Theyoften concentrateonschoolzonesand rushhourroutes.Thedepartment alsostationsvisiblepatrolsona majorthoroughfareundergoing reconstruction,watchingforwork zoneviolations. Researchbeforereacting Publicinformationasadeterrent figuresinthespeedstudiescon- ductedbyHudsonpolice.Chief Jensendescribesthespeedtrailer hisdepartmentusesasservinga dualpurpose:itprovideslocal officialswithaccuratespeeddata anddrawsdrivers’attentionto howfasttheyarereallygoing. Adigitaldisplayonthetrailer showsthelegalpostedspeedand thespeedofindividualvehicles. Thetrackingfeaturegathersdata onthenumberofvehiclesperday, theaveragespeed,howmany vehiclestraveloverthespeedlimit andhowmanyexceeditbyasub- stantialmargin.Officerssome- timesdisabletheread-outsand useitsolelytotrackspeeddata onfree-flowingtraffic. Thedepartmentmovesthe trailertoperceivedproblemareas orinresponsetoaspecificcom- plaint—“Peoplelovetoseeitout there.”Jensensaystheirabilityto trackconditions before mounting acompleteresponsemakesa difference.Insteadofreactively increasingpatrolswhenacom- plaintcomesin,theydotheir research. “Putpatrolsoutonthestreet andtheproblemgoesaway,but onlyforaslongasthepatrols arepresent.Weneededtoknow, whatarethefacts,arepeople reallygoingasfastascomplaints indicateandisitallthetime.” InJensen’sexperience,datafroma speedstudyalsotakestheemotional elementoutofdecisionsbylocal officialspressuredtoredesignroads oraddtrafficcalmingdevices.He citestheexampleofa2-waystop controlledintersectionintheSt. CroixCountycommunitythatwas thesceneofacar/pedestrianacci- dent.Thefirstresponsewasto changeittoa4-waystopintersec- tion.Later,afterevaluatinginforma- tionfromaspeedstudy,officials decidedtorestoretheintersectionto itsoriginal2-waystopdesignand addedmorewarningsigns. Becauseadequatesignageis essentialforsafety,theHudson policeworkcloselywithothercity departmentstoestablishclear policiesforevaluatingspeedissues andrequeststomodifysignsor trafficcontrols. Organizedprocess includesstats Likeotherlocalofficials,Commis- sionerDittmarbelievesingathering thefactsbeforeinstallingmoresigns orchangingaspeedlimit.The MonroeCountyHighwayDepart- mentusesaradargunaspartof itstrafficsafetyprogram. Dittmarsaysthesimpletool servesthemwell,providingunbiased statisticsonvehiclestravelingonthe county’smostlyruralroads.Thefact thatonesizedoesnotfitallisa strongargumentforgettingthe facts,henotes.Wheretrafficisrela- tivelylight,aperceivedspeeding problemmaynotconformtostan- darddefinitionsortextbookfixes. Healsotakesanengineer’sview oftheimpactthatsignage,mainte- nanceandroaddesignhaveon speedcompliance.“Mostpeople driveatspeedstheyfeelaresafe,” heobserves.“Loweringthelimits inresponsetoaperceivedproblem turnsnormaldriversintocriminals.” Thecountyrequiresaformal petitionfromlocallandownerswho requestachange.Thentheydoa speedstudytorecordthe85th percentilespeed,numberofvehicles andvehicletypes,andareasonable representationoftrafficpatternson theroadwayatspecifictimesofday. Dittmarreviewsfindingsfrom bothpetition-relatedstudiesand Contacts JackDittmar MonroeCountyHighway Department 608-269-8740 jdittmar@co.monroe.wi.us FrankFenton CityofMononaPolice Department 608-222-0463 ffenton@ci.monona.wi.us MartyJensen CityofHudsonPolice Department 715-386-4771 mjensen@ci.hudson.wi.us Communicatewithstakeholders Communicatingthefactsisan importantpartoflocalspeed management.MonroeCounty HighwayCommissionerJack Dittmarrecallsalandowner’s requesttolowerthe35mphspeed limitonacountytrunkhighway thathadbecomedenselyresiden- tial.Dittmartooktheopportunity toeducate.Heexplainedthe85th percentileconceptandtherationale formaintainingtheexistinglimiton aroaddesignedtofunneltraffic fromlocalstreetstothestatehigh- way.“Studieshaveshown,”he wroteinresponse,“thatmost motoristsdriveareasonablespeed basedonhowopenorcongested thehighwayisandwillslowdown ifitgetsmorecongestedwith vehiclesand/ordevelopment. Postedspeedlimitslowerthana reasonablemotoristwoulddrive willmainlyresultinreasonable driversgettingticketed.The chancesofcatchingadriverwho racesthroughasectionofhighway areveryremoteandiftheyare drivingthatirresponsibly,aspeed limitchangeof10mphwillnot makeadifference.”Unreasonable legalspeedsbreeddisrespectfor allpostedspeedlimits,headded, notingitisbettertoletthemajority usereasonablejudgment.The residentthankedDittmarforthe analysisandsaiditpersuaded himthepostedspeedwasinfact prudentandsafe. FALL2009 7 UNIVERSITY OF WISCONSIN–MADISON WISCONSIN DIRECTOR StevePudloski,pudloski@epd.engr.wisc.edu STAFFENGINEER BenJordan,jordan@epd.engr.wisc.edu PROGRAMASSOCIATES SusannaFuerstenberg,tic@epd.engr.wisc.edu JaneSauer,tic@epd.engr.wisc.edu WRITER /EDITOR MaryMaher WRITING &CREATIVECONCEPTS GRAPHICDESIGN /LAYOUT SusanKummer ARTIFAX CROSSROADS newsletterprovidesinformationonroadsandbridgesforlocalofficials.Published quarterlybytheWisconsinTransportationInformationCenter(TIC)attheUniversityofWisconsin– Madison,itispartofthenationwideLocalTechnicalAssistanceProgram(LTAP).TICisoperatedby UW–MadisonandissponsoredbytheWisconsinDepartmentofTransportationandtheFederal HighwayAdministration.Forpermissiontoreproducearticlesorgraphics,pleasecontactus. PHONE 800.442.4615 FAX 608.263.3160 EMAIL tic@epd.engr.wisc.edu WEBSITE http://tic.engr.wisc.edu thecleandieselcampaign— incentive-basedprograms,fund- ingsourcesandotherassistance. http://www.epa.gov/otaq/ stateresources/ Linkstobackgroundinforma- tiononDEF (dieselexhaust fluid)anditsuseinSCRemission systems,onecompiledby ColonialChemicalCompany,the otherbyCummins. http://www.urea-scr.com/faq.html http://www.cumminsfiltration. com/pdfs/product_lit/americas_ brochures/MB10033.pdf CommercialCarrierJournal “Updateon2010Engines”pres- entationisarchivedontheweb. ScrolldowntoFebruary2009 webinarpresentation. http://www.ccjwebinars.com/ archives.html DVD/VHS/Multimedia TimelyresourcesnewtoTIC collectionorrelatedtocurrent newslettertopics. WorkingSafelyin ColdWeather, WumbusCorporation, 2007,#19029,DVD,16min. Practicalinformationonworking incoldweather,includingcauses andhealtheffectsofcoldstress, firstaidforhypothermiaand frostbite,andprotectingagainst coldweatherhealthproblems. DefensiveDriving: WhenGoodWeather GoesBad,Wumbus Corporation,2008,#19026, DVD,19min.Goodreviewof drivinginbadweatherwith emphasisonhazardsinheavy rainstorms,includinghydro- planing,poorvisibilityand NEW NEW Publications Flagger’sHandbook,28pp., 2007.Latestpocket-sizedhand- bookonflaggersafetyincludes importantchangesinthefederal ManualonUniformTraffic ControlDevices(MUTCD). WorkZoneSafety:Guidelines forConstruction,Maintenance &UtilityOperations,55pp., 2006.Illustratedhandbook reviewstemporarytrafficcontrol applicationsthatpromotesafety forvehicles,pedestrians,workers andequipment. SettingSpeedLimitsonLocal Roads,TICBulletin#21,6pp., updated2009.Availablefrom TIC.Reviewstheroleoflocal governmentsinsettinglimits. Updateincludesinformation fromnew StatewideSpeed ManagementGuidelines. WebSources TransportationInformation Centersite featuresdownload ofnew StatewideSpeed ManagementGuidelines. http://tic.engr.wisc.edu/ EnvironmentalProtection Agency websitepagewithlinks tostateandlocalresourcesand informationaboutemission reductionstrategies—including othersdoneatrandomwiththe county’sTrafficSafetyCommission, andsharesdatawithlocalofficialsin villagesandtownsacrossthecounty. “Themorewedocumenttravel conditionsonourroads,theeasier itistoaddressquestionsaboutsafe speedsandfindeffectivesolutions.” Hewelcomestheguidelinesasan aidinanalyzingstudyresultsandan endorsementofusingspeedstudies tobackenforcementandplanning decisions. Proactiveproducesresults ResearchbytheNationalHighway TrafficSafetyAdministration(NHTSA) andothergroupsshowthatfocused enforcementaffectscompliance andhelpsreducetravelatunsafe speeds.Communitiesthatcombined enforcementwithdrive-safe messagesexperiencedmeasurable speedreductionintargetedareas. Trafficcalmingmeasures(likepave- mentmarkingsandspeedhumps) alsohelpmodifydriverbehaviors. Findingresourcestotakeproven, proactivetrafficsafetyimprovements isachallenge.WisDOT’sBureauof TransportationSafetyoffersgrants basedoncrashdataanalysisfor localagenciestouseintrafficsafety educationandenforcement. Sharedresponsibility thekey Whatiscommontosuccessfulstate andlocalmeasurestoimprovespeed complianceiscollaborationbetween lawenforcementandtheofficials responsibleformaintainingroads andstreets.Gatheringandsharing usefuldatahelpsstrengthenthat partnershipasdecisionmakersat everylevelgainabetterunderstand- ingofthefactstheyneedtoimple- mentcoordinatedsafetyefforts. flooding.Alsocoverssnow,ice, windandfogconditions,along withtipsontiresafetyandthe safefollowingrule. Pre-TripInspection: ACircleofSafety, WumbusCorporation, 2008,#19027,DVD,14min. Comprehensivereviewofall inspectionpointsadrivershould coverinhis/herpre-tripwalk around.Usefulforcomparing withexistingpre-tripchecklists. Backing,Parking, andIntersections, WumbusCorporation, 2006,#19024,DVD,19min. Defensivedrivingtipsforback- ingandparking,twosituations thataccountformanyfender benders.Includestipsonnegoti- atingsafelycontrolled,uncon- trolledandblindintersections. ChainsawSafety, WumbusCorporation, 1999,#19025,DVD, 13min.Goodintroductionto practicalbasicsofchainsaw safetyforthenewemployee, programalsoservesasacheck forself-taughtusersanda reviewfortheoldhand. TreeTrimming Safety,Wumbus Corporation,1999, #19028,DVD,20min.Agood safetyreviewoftreetrimming equipmentincludingchainsaws, ropes,belts,climbinggear, ladders,polesaws,aerialtrucks, chippersandpersonalprotective gear.Coverssafetyprocedures, crewsize,andoperationplan- ningfortrimming,fellingand buckingnearelectriclines, buildings,andthepublic. NEW NEW NEW NEW Printcopiesofpublications listedinthisissueareavailable freefromTICwhilesupplies last.Downloadorrequestitems at Publications onTICwebsite. Video,CDs,andDVDsloaned freethroughcountyUW- Extensionoffices.Alsoseethe VideoCatalog onTICwebsite. TICwebsite http://tic.engr.wisc.edu/ RESOURCES TICWorkshops Details,locationsandregistrationformsaresentto all Crossroads recipientspriortoeachworkshop. Additionalinformationandonlineregistrationat: http://tic.engr.wisc.edu/workshops/listing.lasso RoadMaintenance Learntorecognize problemsearlyandapplytherightmethods tostretchbudgetsandmaintaingoodlocal roads,streetsandhighways.Includesreview ofnewregulationsforstoppingthespread ofinvasivespeciesandhowtoincorporate thoseeffortsintoROWmaintenanceopera- tions.Fee:$60 Mar11BarneveldMar17Hayward Mar12PewaukeeMar18Tomahawk Mar15TomahMar19DePere Mar16EauClaire WorkZoneandFlaggerSafety Learnto applyWisconsinstandardpracticesandother guidelinesforgoodworkzonetrafficcontrol usingstrategiesthatwillimprovecommuni- cationbetweendepartmentsinvolvedinwork zoneactivities.Presentedateightlocations inearlyApril. CheckTIC websitefor updates. Fee:$60 PRSRTSTD U.S.Postage PAID Madison,WI PermitNo.658 Pleasefilloutthisformandfax ormail(inseparateenvelope) withthemailinglabelbelow. ©2009TIC–LTAPPrintedonrecycledpaper FEEDBACK CALENDAR OnSiteWorkshops Savetimeandtravelcostsbybringinginstruction thatistailoredtoyourspecificneedstoyour shoporoffice.On-siteworkshopsletyoutrain morepeopleforthesamecostorless,including stafffromothermunicipaldepartments,nearby communities,andbusinessesyoucontractwith. ContactTICtobooktheprogramanddateyou want.On-siteworkshopsinclude: •BasicSurveyingforLocalHighwayDepartments •BasicWorkZoneTrafficControl •FlaggerTraining UWMadisonSeminars Localgovernmentofficialsareeligibleforalimited numberofscholarshipsfortheseEngineeringProfessional DevelopmentcoursesheldinMadison.Gotohttp://epd. engr.wisc.eduor800-462-0876forcoursedetails. NOVEMBER2009 910 IntroductoryPrinciplesofEngineering ProjectManagement#K965 1112 ManagementSkillsforEngineering CapitalProjects#K966 13 ComputerToolsforEngineering ProjectManagement#K967 1617 StormSewerDesign#K760 1819 DesigningStormWaterDetention BasinFacilities#K761 DECEMBER2009 79 HighwayBridgeDesign#K856 78 UsingBio/InfiltrationtoImproveStorm WaterManagement#L269 1011 DevelopinganEffectiveSidewalk Program#L155 JANUARY2010 1920 MaintainingAsphaltPavements#L030 2122 ImprovingPublicConstrictionInspection Skills#L034 FEBRUARY2010 23 SoilEngineeringforRoadsand Pavements#L275 45 PavementThicknessDesign#L277 MARCH2010 12 ComprehensivePracticesforEffective ConstructionManagement#K034 3 PrinciplesandPracticesofConstruction ProjectScheduling#K035 45 PrinciplesandPracticesofEstimatingfor ConstructionandDesignProfessionals#K036 IndependentStudy EnrollAnytime ProjectManagement100:TheBasics, PlusImportantInsights#K205 NAME ____________________________________________TITLE /AGENCY _________________________________________ ADDRESS ___________________________________________CITY________________STATE ________ZIP ________________ PHONE__________________________FAX _________________________EMAIL ____________________________________ Mailinglistchange/additionInformation/resourcerequestIdea/comment _____________________________________________________________________________________________ _____________________________________________________________________________________________ _____________________________________________________________________________________________ _____________________________________________________________________________________________ Other ____________________________ ____________________________ ____________________________ ____________________________ ____________________________ ____________________________ ____________________________ CROSSROADS Fall20098 UNIVERSITY OF WISCONSIN–MADISON WISCONSIN WisconsinTransportationInformationCenter 432N.LakeStreetRoom805 Madison,WI53706 Effects of Raising and Lowering Speed Limits on Selected Roadway Sections Publication No. FHWA-RD-97-084 January 1997 U.S. Department of Transportation Federal Highway Administration Research and Development Turner-Fairbank Highway Research Center 6300 Georgetown Pike McLean, Virginia 22010-2296 , I INTRODUCTION This study was conducted to examine driver behavior effects when posted speed limits are raised and lowered on nonlimited access urban and rural highways. In the event that altering the posted speed limits had an impact on traffic speeds, crash data were collected to examine the safety effects. While much research in recent years has focused on the effects of the 55- and 65-mi/h (89- and 105-km/h) speed limits on limited access high-speed facilities, this research concentrated on lower speed urban streets and rural highways that were posted between 20 and 55 mi/h (32 and 89 km/h). A maximum speed limit is posted or set by statute on a highway to inform motorists of the highest speed considered to be safe and reasonable under favorable road, traffic, and weather conditions. A review of early vehicle speed legislation in the United States suggests that speed regulations were established to improve public safety!] The rationale for government regulation of speed is based on the fact that unreasonable speed may cause damage or injury. Speed laws also provide a basis for punishing the unreasonable behavior of an individual driver. Every State has a basic speed statute requiring drivers to operate their vehicles at a speed that is reasonable and prudent under existing conditions.[2] This law recognizes that the maximum safe speed varies due to traffic, roadway, weather, light, and other conditions, and places the responsibility of selecting a safe and reasonable speed on the driver. Most traffic engineers believe that speed limits should be posted to reflect the maximum speed considered to be safe and reasonable by the majority of drivers using the roadway under favorable conditions.[3] Procedures used to set speed limits have evolved through years of experience and research. Most States and localities set maximum speed limits based on the results of an engineering and traffic investigation. The 85th percentile speed is used as a major factor in selecting the appropriate speed limit for a street or highway; however, other factors, such as roadside develop- ment, crash experience, and design speed, are often considered.[3] While traffic engineers and enforcement officials consider a number of factors when determining the speed limit to post, public and political opinions can and do influence their decision. There are a number of strongly held opinions by the public concerning the effects of a posted speed limit. One of the opinions often expressed is that setting low speed limits will reduce vehicle speeds and crashes. Also, it has been frequently suggested that most motorists drive 5 to IO mi/h (8 to 16 km/h) over the posted speed limit, so lower speed limits should be established to account for this condition. Conversely, it is believed that raising the posted speed limit on nonlimited access highways increases vehicle speeds and crashes. For example, following a severe crash, one of the most frequent requests made to highway jurisdictions is to lower the 1 speed limit. These requests are founded on public knowledge that crash severity increases with increasing vehicle speed, because in a collision, the amount of kinetic energy dissipated is proportional to the square of the velocity.Simply stated, when a vehicle is involved in a crash, the higher the vehicle speed, the greater the chance of being seriously injured or killed. However, as noted by a number of researchers, the potential for being involved in a crash is highest when traveling at a speed much lower or much higher than the majority of motorists.[4-7] For years, traffic engineering texts have supported the conclusion that motorists ignore unreasonable speed limits.[8] Both formal research and informal operational observations conducted over many years indicate that there is very little change in the mean or 85th percentile speed as the result of raising or lowering the posted speed limit on urban and rural nonlimited access highways.[9] Highway administrators, enforcement officials, the judiciary, and the public need factual information concerning the effects of posted speed limits on driver behavior for nonlimited access roadways. For example, will lowering the posted speed limit on a two-lane roadway section through a rural community reduce vehicle speeds? Does raising the posted speed limit to the 85th percentile speed on a short segment of roadway increase vehicle speeds? Do most motorists drive 5 to 10 mi/h (8 to 16 km/h) above the posted speed limit? What are the effects of lowering or raising speed limits on driver compliance? OBJECTIVES AND SCOPE The objective of this research was to determine the effects of raising and lowering speed limits on driver behavior for urban and rural nonlimited access highways. During the period the study was conducted, from October 1985 until September 1992, the maximum speed limit was 55 mi/h (89 km/h) on nonlimited access highways. During this time, the locations where States and localities raised and lowered posted speed limits were typically limited to roadway segments less than 2 mi (3.2 km) in length. Consequently, the sites selected for study were limited to roadway sections with an average site length of 1.7 mi (2.7 km). Driver behavior effects examined in this study included the speed distribution (percentile speeds), mean speeds, speed variance, percent of drivers exceeding the posted speed limit, and close following behavior. Anticipating that changing the posted speed limit could have an effect on driver speeds, crash data were collected to examine the safety effects. The crash data included police-reported crashes, crashes involving injury or death, and multiple-vehicle and single-vehicle crashes. It is important to emphasize that this research was limited to examining driver behavior effects as a result of changing the posted speed limit only.It is recognized that enforcement and public education are key components in making any traffic regulation effective, including speed limits. While highly visible enforcement is essential to detecting and deterring speeding motorists, and public educational campaigns can influence motorists’ attitudes, this research did not examine these factors. 2 The scope of the study included the collection of driver behavior and crash data in 22 States, as shown in figure 1. The data were collected at 100 sites on nonlimited access highways, consisting of 172 mi (277 km) where speed limits were either raised or lowered, and at 83 comparison sites, consisting of 132 mi (213 km) where no changes in the posted speed limits were made. Repeated speed measurements were made at 11 selected sites to examine the time effects of speed limit changes.Data were also collected at five sites that were contiguous to four experimental roads to determine if speed limit changes on the experimental sites had indirect effects on driver behavior on the contiguous sections. In April 1987, at the end of the site-selection phase of the study, Congress permitted States to raise speed limits on selected limited access facilities to 65 mi/h (105 km/h). To obtain some information concerning the speed effects on these high- speed facilities, four sites consisting of 94 mi (151 km) were nonrandomly selected in three States. Due to the small sample size and the nonrandom selection of sites, the results of the speed and crash data collected at these sites are not included in the main section of the report, but are discussed in a separate appendix. Participating State Figure 1. States participating in the study. 3 SUMMARY, FINDINGS, AND CONCLUSIONS SUMMARY This research was conducted to examine the effects of raising and lowering posted speed limits on driver behavior for urban and rural nonlimited access roadways. The scope of the study was limited to examining changes in driver behavior when the only change was an alteration in the posted speed limit. Due to legislative requirements, tort liability issues, and public confidence concerns, the participating States and jurisdictions would not permit the research team to randomly select and assign roadway sections for speed limit changes. Because the original study design could not be implemented, experimental sections were selected from locations where transportation agencies planned to change posted speed limits as a result of routine traffic and engineering investigations. Based on safety and opera- tional characteristics, comparison sites were selected by the research team during a field review of the experimental locations. The study was conducted from October 1985 to September 1992, when the maximum speed limit was 55 mi/h (89 km/h) on nonlimited access highways. During this period, the States and localities lowered and raised posted speed limits on short roadway segments, typically less than 2 mi (3.2 km) in length. The general types of sites included in the study were: 1. A roadway section in a small rural town or community where the speed limit on the adjoining roadway sections was 55 mi/h (89 km/h). The length of these sections varied between 0.5 and 1 mi (0.8 and 1.6 km). 2. A roadway section in an urban. suburban. or rural area where public or political requests or increases or decreases in the adjacent land use and corresponding traffic volumes dictated the need for a change in the speed limit. These sections were typically 1 mi (1.6 km) in length. 3.A two- or four-lane nonlimited access roadway section in a rural area where the speed limit was raised to 55 mi/h (89 km/h). These sections were between 2 and 12 mi (3.2 and 19.3 km) in length. Posted speed limits were changed for the following reasons: l As a result of a request from the public, political leaders, or enforcement officials. l To ensure that speed limits were appropriate for roadway and traffic conditions. l As a result of a high incidence of traffic crashes. l To comply with local laws or ordinances. l In response to changing traffic volume and land-use patterns. 83 The study included the collection of driver behavior and crash data in 22 States. The data were collected at 100 sites on nonlimited access highways, consisting of 172 mi (277 km) where speed limits were either lowered or raised, and at 83 compari- son sites, consisting of 132 mi (213 km), where no changes in the posted speed limits were made. Sixty-three percent of the sites selected were in rural areas and small communities with a population of less than 5,000 persons.Ninety-four percent of the sections were two-lane highways. Traffic volumes on the sections ranged from 300 to 17,000 vehicles/day. Of the 100 study sites, posted speed limits were lowered at 59 sites and raised at 41 other locations. Changes in the posted speed limits ranged from lowering the speed limit by 5, IO, 15, or 20 mi/h (8, 16, 24, or 32 km/h) to raising the speed limit by 5, 10, or 15 mi/h (8, 16, or 24 km/h). Only one change in the posted speed limit was made at each site during the study. Speed limits on the experimental sections were changed between July 1986 and May 1989. The before speed data were collected between June 1986 and June 1988. The after speed data were collected between August 1987 and July 1989. Collection of the before data ranged from several days to 2 years prior to the speed limit change. Collection of the after data ranged from several days to as much as 2 years following the speed limit change. The examination of driver behavior data, collected at 98 experimental sections, included the speed distribution (percentile speeds), mean speeds, speed variance, percentage of drivers exceeding the posted speed limit, and close following behavior. Before and after speeds of free-flow vehicles (vehicles with a headway of 4 s or more) were collected for a 24-h period simultaneously at each experimental and comparison site pair. The crash data collected included police-reported crashes, crashes involving injury or death, and multiple-vehicle and single-vehicle crashes. Before and after crash data were collected at 99 experimental sections and their corresponding comparison sections. For most sections, crash data were available for a 3-yr period before the speed limit was changed and for a 2-yr after period. A total of 6,307 police-reported crashes were used in the analysis. Analyses were conducted to examine before-and-after differences in driver behavior at each site. The sites were divided into lowered posted speed limit and raised posted speed limit groups. The sites were further subdivided into groups based on the amount of posted speed limit change. Group means and other statistics were calculated for each of the speed variables collected. Four evaluation methods were used to analyze the crash data. The methods included multiple before and after analyses with paired comparison ratios, the classical cross-product ratio, the new empirical Bayes method, and the before-and-after design using a weighted average logit to produce an overall estimate of safety effects. 84 l The small differences in before and after speeds, as shown in figure 43, were statistically significant due primarily to the large sample size collected. l At 34 locations, existing speed limits were posted within 5 mi/h (8 km/h) of the 85th percentile speeds. When speed limits at these sites were lowered more than 5 mi/h (8 km/h) below the 85th percentile speeds, the mean difference in percentile speeds was less than 1 mi/h (1 .6 km/h). -At 21 other locations, existing speed limits were posted more than 5 mi/h (8 km/h) below the 85th percentile speeds. When the agencies raised the limits to within 5 mi/h (8 km/h) of the 85th percentile speeds at these sites, the mean difference in percentile speeds was less than 1 mi/h (I .6 km/h). l By defining driver compliance as the number or percentage of drivers that travel at or below the posted speed limit, major changes in compliance occurred when speed limits were raised or lowered. However, as reflected in small changes in vehicle speeds, driver behavior did not change, but the standard for measuring compliance, i.e., posted speed limit, changed. l Based on the free-flow speed data collected for a 24-h period at the experi- mental and comparison sites in 22 States, posted speed limits were set, on average, at the 45th percentile speed or below the average speed of traffic. l Only minor changes in vehicles following at headways of less than 2 s were found at the experimental sites with similar before and after traffic volumes. l The indirect effects of speed limit changes on a sample of five contiguous and adjacent roadways were found to be small and insignificant. - There is not sufficient evidence, in this dataset, to reject the hypothesis that total crashes or fatal and injury crashes changed when posted speed limits were either lowered or raised. l There is not sufficient evidence, in this dataset, to reject the hypothesis that total crashes changed when posted speed limits were lowered more than 5 mi/h (8 km/h) below the 85th percentile speeds. - There is not sufficient evidence, in this dataset, to reject the hypothesis that total crashes changed when posted speed limits were raised to within 5 mi/h (8 km/h) of the 85th percentile speeds. l In April 1987, when Congress permitted States to raise speed limits to 65 mi/h (105 km/h) on selected limited access highways, speed and crash data were collected for a sample of four limited access Interstate segments. The findings concerning speed and crashes, which are different than those found on the nonlimited access roadway sites studied, are discussed in appendix G. 86 CONCLUSIONS The general conclusions of this study are: There is statistically sufficient evidence in this dataset to reject the hypothe- sis that driver speeds do not change when posted speed limits are either raised or lowered. However, the differences in speeds are not sufficiently large to be of practical significance, and are due primarily to large sample sizes. Although the changes in vehicle speeds were small, driver violations of the speed limits increased when posted speed limits were lowered. Conversely, violations decreased when speed limits were raised. This does not reflect a change in driver behavior, but a change in how compliance is measured, i.e., from the posted speed limit. The majority of motorists did not drive 5 to 10 mi/h (8 to 16 km/h) above the posted speed limit when speed limits were raised, nor did they reduce their speed by 5 to 10 mi/h (8 to 16 km/h) when speed limits were lowered. Based on the sites selected for this study, it appears that highway agencies have a tendency to set speed limits slightly below the average speed of traffic. Changing posted speed limits alone, without additional enforcement, educa- tional programs, or other engineering measures, has only a minor effect on driver behavior. There is not sufficient evidence in this dataset to reject the hypothesis that crash experience changed when posted speed limits were either lowered or raised. 87 SUGGESTIONS FOR FUTURE RESEARCH Based on the results of this research, the following areas are suggested for further investigation: There is an immediate need to examine the State policies and practices used to set posted speed limits on nonlimited access facilities. In particular, attention should be given to identifying factors or a method that leads to establishing uniform speed limits for similar roadway and traffic conditions. The use of automated equipment and other alternative economical means of collecting unbiased speed data used to set speed limits should be explored as an alternative to the conventional use of radar. Actual prevailing speed data for a variety of roadway geometrics and highway systems should be summarized and provided to design engineers for use as a guideline when setting the design speed on a proposed roadway project. The implications of setting speed limits based on samples obtained by using an hourly or minimum vehicle requirement should be reexamined. Based on the 2-h data collection increments from the current study, as well as recent research conducted in Michigan, wide variations in the 85th percentile speeds occurred throughout the 24-h recording periods.[21] In addition, the hourly variations were not consistent from site to site. This suggests that speed samples should be taken throughout the day to obtain a representative sample of the 85th percentile speed, as opposed to collecting a sample over a short time period such as 2 h. 88 Wisconsin Statewide Speed Management Guidelines June 2009 Developed by the Wisconsin Department of Transportation Bureau of Highway Operations, Traffic Engineering Section 4802 Sheboygan Ave., Room 501 P.O. Box 7910 Madison, WI 53707-7910 i Table of Contents Introduction .........................................................................................................................1 Background on Speed Limits ..........................................................................................1 Speed Zones ....................................................................................................................1 Standard Language..........................................................................................................3 Context of Potential Speed Zones .......................................................................................3 Assessing Need for a Speed Zone or for Modification .......................................................4 Step 1: Identify and Inform Stakeholders .......................................................................4 Step 2: Collect Location-Specific Data...........................................................................5 Data Collection Guidelines and Considerations.........................................................6 Data Collection Methods ............................................................................................8 Step 3: Analyze Data and Develop Study Conclusions ................................................14 Step 4: Develop Speed Zone Recommendations ..........................................................16 Recommending a Speed Limit Change.....................................................................17 Recommending No Speed Limit Change .................................................................19 Step 5: Report Draft Results, Conclusions, and Recommendations .............................20 Step 6: Seek Stakeholder Support .................................................................................20 Procedure for Roadways in the State Trunk Highway System .................................21 Procedure for Other Roadways .................................................................................21 Establishing or Modifying a Speed Zone..........................................................................21 Procedure for Roadways in the State Trunk Highway System .....................................21 Procedure for Other Roadways .....................................................................................22 Post Speed Limit Signs .................................................................................................22 Monitoring Performance ...................................................................................................22 Attachment A: Speed Study Report Template and Worksheet Attachment B: Example Wisconsin County Numbering System Wisconsin Statewide Speed Management Guidelines June 2009 Introduction The purpose of this document is to provide uniform guidelines for the establishment or adjustment of speed zones on Wisconsin’s state highways and local roads. The application of uniform guidelines will move the Wisconsin Department of Transportation (WisDOT) toward its goal of setting rational speed limits throughout the state based on sound traffic engineering principles as recommended in the Wisconsin Strategic Highway Safety Plan 2006–2008. The guidelines will also promote a consistent study methodology and provide a uniform speed study reporting format, allowing for efficient review of speed studies by state or local authorities. Numerous transportation professionals throughout the state are charged with providing and operating a safe and efficient roadway system. The consistent application of rational speed management procedures is vital in maintaining motorist safety and efficiency on the system. Background on Speed Limits Policy makers, transportation professionals, and law enforcement agencies use speed limits to convey the maximum permitted travel speed for a roadway under ideal conditions to motorists. Setting reasonable travel speeds, also called rational speed limits, has the greatest effect on achieving voluntary driver compliance. High rates of speed limit compliance promote mobility, because traffic flows more efficiently when vehicles move uniformly at the highest reasonable speed. High rates of compliance also promote safety by increasing the number of motorists traveling at or near the same speed. When the speed differential is high, it is more likely that crashes will be more severe, cause more property damage, and result in more injuries. Wisconsin State Statutes Section 346.57(4) defines speed limits for all public roadways based on factors that include surrounding land use, roadway jurisdiction, and roadway type. These speed limits, referred to as statutory speed limits, are summarized in Table 1. Speed Zones While state statute establishes speed limits for roadways, Section 349.11 also gives state and local governments administrative authority to change the speed limit on a roadway. The statute vests WisDOT with authority to modify speed limits on the state trunk highway (STH) system and local governments with authority to modify speed limits on the local road system within constraints.1 The changed speed limit is called a modified speed limit, and the segment of roadway that exhibits the modified speed limit is called a speed zone. Speed zones may be appropriate where land use, access, traffic volumes, or crash history call for a change from the statutory speed limit. Table 1 summarizes state and local government authority to establish speed zones. 1 The statute vests WisDOT with approval authority over proposed changes to speed limits on the local road system that are outside the constraints identified in Table 1. 1 Wisconsin Statewide Speed Management Guidelines June 2009 Table 1 Speed Limits and Authority to Change Fixed Limits – Statute 346.57(4)(a) Local Government Authority(b) – Statute 349.11(3) and (7)(a) 65 mph – Freeway / Expressway WisDOT only. 55 mph – State Trunk Highways (STHs) WisDOT only. 55 mph – County Trunk Highways (CTHs), town roads Lower the speed limit by 10 MPH or less. 45 mph – Rustic roads Lower the speed limit by 15 MPH or less. 35 mph – Town road (1,000’ min) with 150’ driveway spacing Lower the speed limit by 10 MPH or less. 25 mph – Inside corporate limits of a city or village (other than outlying district) Raise the speed limit to 55 mph or less. Lower the speed limit by 10 mph or less. 35 mph – Outlying district(c) within city or village limits Raise the speed limit to 55 mph or less. Lower the speed limit by 10 mph or less 35 mph – Semi-urban district(d) outside corporate limits of a city or village Raise the speed limit to 55 mph or less. Lower the speed limit by 10 mph or less. 15 mph – School zone, when conditions are met Raise the speed limit to that of the roadway. Lower the speed limit by 10 MPH or less. 15 mph – School crossing, when conditions are met Raise the speed limit to that of the adjacent street. Lower the speed limit by 10 MPH or less. 15 mph – Pedestrian safety zone with public transit vehicle stopped No changes permitted. 15 mph – Alley Lower by 10 MPH or less. 15 mph – Street or town road adjacent to a public park Lower by 10 MPH or less. Construction or maintenance zones, as appropriate(e) State and local agencies have authority to establish. Notes: (a) Source: Updated 2007-2008 Wisconsin Statutes Database (b) All speed limit changes shall be based on a traffic engineering study, including modifications allowed under State Statute. Local governments can implement speed limit changes on the local road system without WisDOT approval when proposals are within the constraints identified above. (c) Per Statute 346.57(1)(ar) “outlying district” is an area contiguous to any highway within the corporate limits of a city of village where on each side of the highway within any 1,000 feet buildings are spaced on average more than 200 feet apart. (d) Per Statute 346.57(1)(b) “semiurban district” is an area contiguous to any highway where on either or both sides of the highway within any 1,000 feet buildings are spaced on average less than 200 feet apart. (e) Guidance on establishing speed limits in work zones is available in https://trust.dot.state.wi.us/extntgtwy/dtid_bho/extranet/manuals/tgm/13/13-05-06.pdf. Modified from original found in WisDOT Traffic Guidelines Manual, Chapter 13-5-1, Figure 1, June 2009. 2 Wisconsin Statewide Speed Management Guidelines June 2009 Standard Language In this guidance, the verbs shall and should are used consistent with national and WisDOT guidelines, including the Federal Highway Administration (FHWA) Manual on Uniform Highway Control Devices (MUTCD), WisDOT Facilities Development Manual (FDM), and WisDOT Traffic Guidelines Manual (TGM). Use of the verbs is characterized as follows: 1. Shall - a statement of required, mandatory, or specifically prohibitive practice regarding performing a speed study or modifying a speed limit. The verb shall consistently appears in bold type. 2. Should - a statement of recommended, but not mandatory, practice in typical situations, with deviations allowed if engineering judgment or engineering study indicates the deviation to be appropriate. The verb should consistently appears in unbold, italicized type. Context of Potential Speed Zones Effective speed zones are established relative to their surroundings. A number of factors contribute to a roadway’s context, including physical, geographic, and political conditions. Physical conditions form the driving environment, which is the main influence on motorist speed. The physical attributes of a roadway that significantly influence vehicle speeds include: • Traffic characteristics such as total traffic volume, truck percentage, turn movement volumes, and local versus regional traffic • Characteristics of roadside development such as type of land use, density, and development’s lateral offset from the roadway • Roadway design elements including number of lanes, shoulder, clear zone widths, and presence of horizontal and vertical curves • Roadway pavement condition • Access characteristics including number, type, and design of roadway and driveway intersections • Presence of on-street parking adjacent to travel lanes • Presence of bicycles or pedestrians on, along, or crossing the roadway • Level of maintenance such as snow and ice removal A roadway’s posted speed limit and its physical attributes communicate to a great extent the driving experience that motorists should expect. But geography also contributes to this perception, including the location of the roadway within rural or urban settings. For example, the statutory speed limit on freeways is 65 mph. But on some freeways passing through urban areas, WisDOT has established speed zones with 55 mph speed limits to account for more lanes, narrower shoulders and clear zones, more closely spaced interchanges, and higher traffic volumes when compared to typical freeways in rural 3 Wisconsin Statewide Speed Management Guidelines June 2009 areas. Urban settings vary from dense urban core; urban fringe; suburban area; or small, isolated urban land development (less than 1/4- to 1/2-mile long) located within an otherwise rural setting. Together, the physical attributes and the geographic location of a roadway (urban or rural) support a driver’s expectation of a reasonable speed limit. Although physical and geographic attributes provide elements of speed zone context, political conditions can also significantly contribute to speed limit determination. Political conditions are largely set by interested stakeholders. It is important for analysts to inform stakeholders and seek their support throughout the speed study process. For freeways, which carry Interstate highway and state trunk highway (STH) designations, WisDOT, including the State Patrol, and the Federal Highway Administration (FHWA) are generally the primary stakeholders as local governments do not have direct access to the freeway. For non-freeways, which carry STH, county trunk highway (CTH), local road, and urban street designations, WisDOT, local governments, traffic safety commissions, and local law enforcement are generally the primary stakeholders. Assessing Need for a Speed Zone or for Modification In order for a state or local authority to establish or modify a speed zone along a roadway, a speed study shall be performed that evaluates need for a speed zone or for modification of an existing speed zone. The process for completing a speed study shall be the same for both state and local authorities; however, it is acknowledged that specific details of the process may occasionally differ by jurisdiction, depending on factors such as time constraints, resources at-hand, and budget limitations. The following text presents the process by which a speed study shall be performed and recommends data collection procedures and required documentation. Essentially, the speed study process consists of applying the six steps listed below: 1. Identify and inform stakeholders. 2. Collect location-specific data. 3. Analyze data and develop study conclusions. 4. Develop speed zone recommendations. 5. Report draft results, conclusions, and recommendations. 6. Seek stakeholder support. Step 1: Identify and Inform Stakeholders Requests for speed studies originating outside of WisDOT for STHs or the local authority for local roads should come through a mayor or other elected executive, appointed official, government body 2 , or a Traffic Safety Commission and be submitted in writing. WisDOT or the local authority shall evaluate the request and use it in identifying primary 2 WisDOT regions contacted directly by state or national legislators should notify and coordinate with the WisDOT Bureau of Highway Operations, Traffic Engineering Section. 4 Wisconsin Statewide Speed Management Guidelines June 2009 stakeholders. If study is not warranted, WisDOT or the local authority shall inform primary stakeholders in writing of this finding and provide supporting rationale. If study is warranted, WisDOT or the local authority shall inform primary stakeholders before the speed study is initiated, but shall minimize bias in the data collection effort by avoiding disclosure of specific study dates or times. WisDOT or the local authority should take the opportunity to brief decision-makers early in the speed study process, especially when the study area includes local roads or driveway access and passes through local jurisdictions. Briefings should include how recommendations are developed and how they will be communicated as the study concludes. WisDOT or the local authority should coordinate with municipal and county officials, such as engineers, public works directors, and law enforcement, to access their local knowledge and identify vital information, especially in crash analysis, as the information may affect recommendations resulting from the speed study. Step 2: Collect Location-Specific Data The objective of a speed study is to assess whether the speeds at which motorists travel along a stretch of roadway appropriately relate to the existing physical and geographic environment. State and local speed zone studies shall collect the following location- specific data: • Vehicle speeds • Crash data for the preceding three to five years including crash location, light/weather/pavement conditions, type of crash, and contributing factors such as speed • Roadway geometrics including lane width and pavement condition, shoulder width and condition, and sight distances • Traffic control and posted speed limits in, and in close proximity to, the study area • Land uses including type of development and intensity and access points from adjoining parcels, lots, or fields onto the roadway • Official functional classification of the roadway, which indicates how the road is intended to function in the overall state and local highway system. Classifications include principal arterial, minor arterial, collector and local road. Interstates and most routes in the Wisconsin STH system are designated principal arterials. Major local roadways and some routes in the STH system are designated minor arterials, with other important local roads and a few STH routes designated collectors. Other local roads are classified as local roads. 3 • Practical function of the roadway, which indicates the analyst’s perception of the actual function of the roadway within the state and local highway system 3 Additional information on functional classification is available in the FHWA Functional Classification Guidelines (http://www.fhwa.dot.gov/planning/fcsec1_1.htm) or by contacting WisDOT Regional offices. 5 Wisconsin Statewide Speed Management Guidelines June 2009 The above-mentioned data is required for all speed studies. Supplemental observations may also help in establishing a fuller understanding of current traveling conditions in the study area. Therefore, the speed study should also include, but is not limited to, the following information if pertinent: • Presence of conflicts with parked vehicles, pedestrians, and bicycles in the study area • Proximity to schools • Current level of speed enforcement in the study area Data Collection Guidelines and Considerations The data collection process is the foundation of the speed study. Speed observations collected properly with minimal motorist detection will provide a better representation of vehicle speeds in the study area and will lead to more valid study conclusions and recommendations. For this reason, an unmarked car is recommended, and the speed data collection device should be located as inconspicuously as possible. Several issues regarding the physical and environmental conditions of the speed zone study area should be taken into account before collecting speed data. These considerations include: • Day and time to perform the speed study • Study location • Observer location and position • Data sample characteristics When a speed study is performed, regardless of the data collection method applied, a standard operating procedure should be followed to ensure that the sample set of data collected represent vehicles traveling at uninterrupted, free-flow speeds. In doing so, an accurate representation of vehicle speeds within the speed zone study area will be depicted. The following outlines the recommended procedure that should be followed when performing a speed study: • The speed study should be performed during non-peak traffic conditions on a typical weekday (usually a Tuesday, Wednesday, or Thursday), when motorists are likely to be traveling at uninterrupted speeds. Speed studies conducted during peak commuter times, unique events, weekends, or holidays may unintentionally capture more variable travel characteristics. These variable traffic conditions may impede vehicles from operating at their typical free-flow speeds due to congestion or platooning. In addition, the speed data should be collected during daylight hours and favorable weather conditions to reflect typical driving behavior. In certain cases, though, speed concerns on a particular roadway do involve adverse weather or peak traffic volume conditions (e.g., school startup and release times, shift changes at major employment centers, or corridors with numerous points of commercial access). In these cases, it would be appropriate to conduct a speed study under these conditions to observe vehicle speeds during these unique situations. 6 Wisconsin Statewide Speed Management Guidelines June 2009 • Speed data should be collected away from factors that might influence vehicle speeds, such as railroad crossings, intersections, horizontal and vertical curves, and work zones. The location of the speed study should avoid speed limit transition areas and active pedestrian and on-street parking areas as motorist awareness is heightened, which may influence their free-flow speeds. • Regardless of the data collection device being used, safety shall be the first priority when the observer or technician is performing this task. Although the amount of human interaction in collecting speed data varies by device, the observer or technician shall not be placed in a situation where their safety or that of passing motorists is in question. • Speed data for the speed study is typically collected by recording the speeds of free- flowing vehicles using a speed-measuring device. A representative sample of speeds is recorded, which include local residents, commuters, and regional traffic. To assist in obtaining accurate speed measurements, the observer or speed-measuring device should be inconspicuous to the observed traffic so unusual driver behavior does not skew data. • Whenever possible, a minimum sample size (number of observations) for a speed study should not be less than 100 vehicles per lane per direction to provide an accurate representation of vehicle speeds within the study area4 (e.g., a total of 200 vehicles for a roadway with one lane in each direction, or 400 vehicles total for a roadway with two lanes in each direction). For roadways classified as “Very-Low Volume Local Roads”,5 the minimum sample size should not be less than 30 vehicles (e.g., 15 vehicles per direction on a two-lane roadway). If the analyst anticipates that a sample of 30 vehicles cannot be collected within a reasonable amount of time, the submitting party shall request approval to use a smaller sample size from the agency with jurisdiction over the roadway. Data can be collected over multiple weekdays (typically a Tuesday, Wednesday, or Thursday), as discussed previously. • When an observer is gathering speed data, vehicle headway (the time between successive vehicles) of four to six seconds should be present for reliable speed observations. Measurements collected with smaller headways may not reflect free- flow conditions, as the lead vehicle may influence the speed of the vehicle(s) behind it. • A minimum of one hour shall be the minimum amount of time to perform a speed study. 4 Wolfgang Homburger, Jerome Hall, William Reilly, and Edward Sullivan. Fundamentals of Traffic Engineering, 15th Edition. Institute of Transportation Studies, University of California-Berkeley, 2001. 5 ADT of less than 400, as defined in AASHTO Guidelines for Geometric Design of Very-Low Volume Local Roads, 1st Edition, 2001. 7 Wisconsin Statewide Speed Management Guidelines June 2009 Avoiding Bias in Sampled Data When an observer collects speed measurements using a hand-held speed-measuring device, the observer should collect speed data by randomly selecting vehicles to measure, without bias toward certain vehicles that may be encountered. The following are examples of situations that should be avoided so as to not skew the study results: • Fast or slow vehicles. Avoid favoring vehicles that are perceived by the observer to be going fast or slow relative to the rest of the vehicle stream. • Platoon leaders or followers. Avoid favoring vehicles that are the lead car in a platoon, also called platoon leaders, or vehicles that are immediately behind the lead car in a platoon, known as platoon followers. • Trucks and buses. Avoid favoring observation of trucks and buses. Because of their prominent size, trucks and buses may be favored for observation and may operate at speeds which are different than passenger cars. In each of these situations, collecting a disproportionate number of these vehicles may create a bias toward higher or lower speeds in the sample. To avoid these biases, the observer should consider randomly selecting vehicles to measure, or measure every ‘nth’ vehicle when traffic volumes allow. Speed data collected from trucks and buses should be analyzed separately from passenger vehicle data. Data Collection Methods An analyst or agency can use a variety of data collection devices. These devices can be grouped into three categories, which for these purposes, are based on the location that the speed data collection device is installed: • Manually-operated, handheld devices that are portable and can be used in most places (e.g., stopwatch, radar gun, and laser gun). • In-road devices that are installed into or on top of the roadway surface (e.g., pneumatic road tube). • Out-of-road devices that are installed overhead or to the side of the roadway surface (e.g. radar recorders). Each device has distinct advantages and disadvantages for collecting and analyzing data that may factor in determining the appropriate device to use for a particular location. The analyst or agency should make a concerted effort to use devices that incorporate the most advanced data collection technologies available to them. In doing so, a more accurate representation of vehicle speeds can be obtained while minimizing observer-related biases. Table 2 summarizes several common speed data collection techniques and the following section describes the methodologies and processes for each one. 8 Wi s c o n s i n S t a t e w i d e S p e e d M a n a g e m e n t G u i d e l i n e s June 2009 9 Ta b l e 2 Co m p a r i s o n o f D a t a C o l l e c t i o n M e t h o d s Me t h o d Da t a C o l l e c t e d La b o r In v o l v e m e n t Eq u i p m e n t Co s t s 1 Ad v a n t a g e s Di s a d v a n t a g e s Ra d a r R e c o r d e r s In s t a n t a n e o u s s p e e d , tr a f f i c v o l u m e s , ve h i c l e c l a s s , t r a f f i c fl o w g a p s 3 Lo w Hi g h Li t t l e l a b o r r e q u i r e d t o c o l l e c t a n d ta b u l a t e d a t a : C a n c o l l e c t d a t a f o r l o n g pe r i o d s o f t i m e ; O t h e r t r a f f i c - r e l a t e d da t a m a y b e c o l l e c t e d a t t h e s a m e ti m e ; C a n b e u s e d w h e n s n o w p l o w s ma y b e p r e s e n t w i t h o u t r i s k o f da m a g e ; L e s s v i s i b l e t o t r a v e l i n g pu b l i c t h a n r o a d t u b e s Us e r c a n n o t r a n d o m l y s e l e c t v e h i c l e s fo r d a t a s e t ; S o m e d e v i c e s m a y n o t ac c u r a t e l y c o l l e c t d a t a f o r m u l t i - l a n e ro a d w a y s a n d / o r d e t e r m i n e di r e c t i o n a l i t y o f o b s e r v e d v e h i c l e s ; Eq u i p m e n t - i n t e n s i v e m e t h o d ; Ma i n t e n a n c e / c a l i b r a t i o n r e q u i r e d Pn e u m a t i c R o a d Tu b e In s t a n t a n e o u s s p e e d , tr a f f i c v o l u m e s , ve h i c l e c l a s s , t r a f f i c fl o w g a p s 3 Lo w Me d i u m Li t t l e l a b o r r e q u i r e d t o c o l l e c t a n d ta b u l a t e d a t a ; C a n c o l l e c t d a t a f o r l o n g pe r i o d s o f t i m e ; O t h e r t r a f f i c - r e l a t e d da t a m a y b e c o l l e c t e d a t t h e s a m e t i m e Vi s i b l e t o t r a v e l i n g p u b l i c w h i c h m a y ch a n g e d r i v e r b e h a v i o r ; U s e r c a n n o t ra n d o m l y s e l e c t v e h i c l e s f o r d a t a s e t ; Us e d i s c o u r a g e d w h e n s n o w p l o w s m a y be p r e s e n t ; M o s t e q u i p m e n t - i n t e n s i v e me t h o d ; M a i n t e n a n c e / c a l i b r a t i o n re q u i r e d La s e r G u n In s t a n t a n e o u s s p e e d Me d i u m Hi g h Eq u i p m e n t i s e a s i l y p o r t a b l e ; U s e r co n t r o l s v e h i c l e s s a m p l e d a s a m o r e fo c u s e d l a s e r b e a m l i m i t s t h e n u m b e r of r e a d i n g s f o r n o n - t a r g e t v e h i c l e s a s co m p a r e d t o r a d a r Co s i n e e r r o r l i m i t s h o r i z o n t a l / v e r t i c a l de p l o y m e n t ; S c o p e s a n d s i g h t s m a y n o t be u s e r - f r i e n d l y ; L a s e r b e a m s m o r e se n s i t i v e t o e n v i r o n m e n t a l v a r i a n c e s th a n r a d a r ; M a i n t e n a n c e / c a l i b r a t i o n re q u i r e d Ra d a r G u n In s t a n t a n e o u s s p e e d Me d i u m Me d i u m Eq u i p m e n t i s e a s i l y p o r t a b l e ; U s e r co n t r o l s v e h i c l e s s a m p l e d ; A c c u r a t e da t a c o l l e c t i o n m e t h o d ; W i d e s p r e a d eq u i p m e n t a v a i l a b i l i t y h a s l o w e r e d i t s co s t Co s i n e e r r o r l i m i t s h o r i z o n t a l / v e r t i c a l de p l o y m e n t ; C l o s e l y - s p a c e d a n d l a r g e r ve h i c l e s m a y c r e a t e r e a d i n g s f o r n o n - ta r g e t e d v e h i c l e s ; Ma i n t e n a n c e / c a l i b r a t i o n r e q u i r e d St o p w a t c h 2 Tr a v e l t i m e o v e r a di s t a n c e Hi g h Lo w Li t t l e e q u i p m e n t t o p u r c h a s e a n d ma i n t a i n ; E a s y t o p e r f o r m d a t a co l l e c t i o n p r o c e s s La b o r - i n t e n s i v e ; C o l l e c t s t i m e d a t a t h a t ne e d s t o b e c o n v e r t e d t o s p e e d d a t a ; Ty p i c a l l y l o w a c c u r a c y 1 E q u i p m e n t c o s t s r e f l e c t t h e i n i t i a l p u r c h a s i n g c o s t s o f t h e e q u i p m e n t a n d n o t f u t u r e m a i n t e n a n c e a n d c a l i b r a t i o n c o s t s 2 T h e s t o p w a t c h m e t h o d s h a l l n o t b e u t i l i z e d i n S t a t e - s p o n s o r e d s t u d i e s o r s t u d i e s t h at i n v o l v e r o a d w a y s u n d e r t h e j u r i s d i c t i o n o f W i s D O T . 3 T h e a m o u n t o f a d d i t i o n a l d a t a c o l l e c t e d v a r i e s f o r e a c h d e v i c e , p l e a s e c o n s u l t t h e d e v i c e ’ s u s e r m a n u a l f o r a b e t t e r u n d e r s t a nd i n g o f i t s c a p a b i l i t i e s . Wisconsin Statewide Speed Management Guidelines June 2009 10 Current Data Collection Methods The following describes data collection methods that use current technologies to accurately collect speed data while minimizing driver awareness of the device and associated observer-related biases. When performing a speed study, it is recommended that the high-technology devices be considered first for deployment to capture vehicle speed data. Radar Recorders Methodology. Radar recorders use the Doppler principle to obtain vehicle speeds. This is performed by a module that emits radar or microwave energy that reflect off of moving vehicles. The device collects the returning waves and uses them to generate an instantaneous measurement of speed. Equipment. Radar recorders typically are constructed as pole-mounted modules that are affixed to a signpost, utility pole, or overhead sign. In addition, law enforcement speed boards also use radar technology that can function as data collection devices; however, the speed limit visual display shall be turned off so motorists do not alter their speeds because of the speed board. Process. The analyst secures the radar recorder to a fixed object outside the traveled way based on the device’s user manual (for speed boards, it should be parked well off the traveled way to avoid motorist collision). The radar recorder is left to collect data for a predetermined period of time and then is collected from the field. Data collected by the recorder is downloaded to a computer for further analysis. Advantages/disadvantages: Radar recorders provide the least labor-intensive method, only requiring a technician to install and remove the module or speed board. Because of this, many of the observer-related errors that may occur with other methods are eliminated. Radar recorders can collect data for long periods of time, and some recorders also include software that can tabulate traffic volumes and distinguish vehicle classes. Because radar recorders are installed outside of the traveled way, they are not readily noticeable to the traveling public (as previously mentioned, it is recommended that the visual display of a radar speed board be turned off to increase its inconspicuousness). Radar recorders measure speed data for all vehicles that pass through the capture zone, which may include vehicles that are not traveling at free-flow speeds. Dependent on the device, some radar recording devices cannot accurately collect speed data along multi-lane roadways due to device limitations. Furthermore, some radar recorders are unable to distinguish directionality of observed vehicles. Because radar recorders rely on equipment to perform the data collection task, they require more maintenance and calibration to uphold its accuracy. Wisconsin Statewide Speed Management Guidelines June 2009 Pneumatic Road Tube Method Methodology. The pneumatic road tube method uses a set of pneumatic road tubes that are attached to an electronic counter with air-sensitive switches. When a vehicle passes over a road tube, the pressure created in the tube actuates a switch in the counter. The amount of time it takes to receive actuations from the two tubes is then converted into an instantaneous speed measurement. Equipment. The pneumatic road tube method is performed using two road tubes and a recorder, devices to attach and secure the road tubes to the roadway and the counter to a fixed object for security, and a measuring tape. Process. The analyst installs the road tubes on the roadway surface, spaced at a specified length based on the counter’s user manual. The road tubes are then attached to the counter and the counter is secured to a fixed object (e.g. tree, sign post, or light pole) so it will not be tampered with or stolen. The counter and road tubes are left to collect data for a predetermined period of time and then are collected from the field. Data collected by the counter is downloaded to a computer for further analysis. Advantages/disadvantages: The pneumatic road tube method possesses many of the same advantages and disadvantages that can be found by using radar recorder devices. Pneumatic road tubes require little labor to collect speed data, eliminating observer-related errors. Pneumatic road tubes can collect data for long periods of time, and some traffic counters also include software that can tabulate traffic volumes and distinguish vehicle classes. Pneumatic road tubes measure speed data for all vehicles that pass over them, which may include vehicles that are not traveling at free-flow speeds. This method also relies on equipment to perform the data collection task and, therefore, requires more maintenance and calibration to uphold its accuracy. Unlike radar recorders, though, some pneumatic road tube traffic counters can be configured to collect the directionality of observed vehicles with only one device, provided a median is present to store the traffic counter. In addition, some traffic counters can be configured to collect data along multi-lane roadways. However, pneumatic road tubes are more visible to the traveling public, which could influence driver behavior as they cross them. Pneumatic road tubes are also discouraged for winter-time use due to the affect of cold weather on counter performance and the potential for snow plows to damage the road tubes and/or counter. Installation and removal of the pneumatic road tubes requires the analyst to work within the traveled way, raising safety concerns and potentially conflicting with the traveling public. 11 Wisconsin Statewide Speed Management Guidelines June 2009 Other Data Collection Methods Other data collection methods are also available for use in collecting vehicle speeds. These methods range from labor-intensive because they require an observer to collect the data (i.e., Laser Gun, Radar Gun, or Stopwatch) to more technologically advanced (e.g., devices that emit microwave or infrared beams). The labor-intensive methods may be more viable for agencies with limited resources to purchase or borrow radar recorder or pneumatic tube technologies, or with limited resources to hire outside data collection services. Laser Gun Method Methodology. The laser gun technology uses laser beams to obtain vehicle speeds. Similar to the radar gun, a handheld device (or ‘gun’) emits a laser beam that reflects off of moving vehicles. The device collects the returning beams and converts the amount of time for the beam to emit and return into an instantaneous speed measurement. Equipment. The laser gun method is performed using a laser gun, a mounting device (if applicable), and data collection forms. Process. An observer ‘shoots’ the laser gun at approaching vehicles and records the speed data transmitted by the laser gun on the data collection form. The speed data is then processed for further analysis. Advantages/disadvantages. The laser gun possesses many of the advantages for use like the radar gun; however, unlike the radar gun, the laser gun emits a concentrated beam of light, which enables the observer to target exactly those vehicles he/she wishes to collect speed data and not inadvertently receiving speed data from non-targeted vehicles. The laser gun also possesses many of the limitations of the radar gun, such as tolerance, maintenance, and calibration. Because the laser gun uses laser beams to collect data, the observer must target vehicles using a scope and sights attached to the device, which may not be as user-friendly as radar guns. Furthermore, laser-light beams are more sensitive to climate conditions, such as precipitation and humidity, which may interfere with readings. Radar Gun Method Methodology. The radar gun method uses the Doppler principle to obtain vehicle speeds. This is performed by a handheld device (typically called a ‘gun’) that emits radar or microwave energy that reflect off of moving vehicles. The device collects the returning waves and uses them to generate an instantaneous measurement of speed. 12 Wisconsin Statewide Speed Management Guidelines June 2009 Equipment. The radar gun method is performed using a radar gun, a mounting device (if applicable), and data collection forms. Process. An observer ‘shoots’ the radar gun at approaching vehicles and records the speed data transmitted by the radar gun on the data collection form. The speed data is then processed for further analysis. Advantages/disadvantages. Technologically, the radar gun method is one of the most accurate ways to measure vehicle speeds. The radar gun is portable and can be mounted to a vehicle or tripod for use. Radar guns allow the observer to collect and distinguish speed data from vehicles traveling in both directions of the roadway. The observer should consult the reference manual of the radar gun before application to determine the device’s effective range and tolerance. One particular tolerance, known as cosine error, limits the horizontal and vertical location an observer can be positioned relative to the roadway. Because beams from the gun are emitted in the shape of an inverse funnel, the speeds of non- targeted vehicles may be transmitted due to the distance of non-targeted vehicles and the targeted vehicle as well as the amount of reflective surface each vehicle possesses. As with most data collection devices, the radar gun requires maintenance and calibration to ensure accuracy. Stopwatch Method Methodology. The stopwatch method measures the time a vehicles takes to pass between two points of a known distance. From the time data collected, speed can be calculated. Equipment. The stopwatch method is performed using a stopwatch (or similar time-measuring device, such as certain electronic traffic count boards), a measuring tape or wheel, a data collection form, and posts or other objects to use as starting and ending reference points (if necessary). Process. The observer first uses the measuring tape or wheel to establish a known length of roadway. The start and end points of this roadway section are then delineated using posts or other objects placed away from the traveled lanes that can be identified by the observer (existing objects in the field such as pavement cracks, utility poles, and trees can suffice as well). The observer then measures the amount of time vehicles take to travel from the start to end points and records it on the data collection form. After a sufficient number of time data records have been collected, the analyst converts the time data into speed data for further analysis. Advantages/disadvantages: The stopwatch method can usually be performed without purchasing additional equipment, reducing costs for the purchase and maintenance of speed-collecting devices. While the stopwatch method is relatively simple to perform, it is also the most labor-intensive to conduct due to the setup of the study area and conversion of time data into speed data. The 13 Wisconsin Statewide Speed Management Guidelines June 2009 stopwatch method includes numerous factors that must be considered to ensure accurate data collection. Additional Technologies Speed data collection may be performed using other methods. The “floating car” or “pacing” method relies on an observer physically driving through the study area while following random vehicles, noting speed or time data of the random vehicle. This technique is more commonly used for travel time and delay studies where space-mean speeds are of greater concern. Other methods gaining popularity in larger cities and state transportation agencies involve out-of-road devices that emit microwave or infrared beams to count and measure vehicle speeds. Finally, devices such as inductive loops can be installed under the roadway surface. When vehicles pass through the loop’s electrical field, recorders note the speed of vehicles passing over them. This methodology requires extensive installation time and costs and is, therefore, not recommended for use on speed zone modification studies. As previously mentioned, each device and technique has its distinct advantages and disadvantages for collecting and analyzing speed data, and it is up to the analyst or agency to select the most appropriate data collection method for a particular location. It is recommended that the analyst use the most technologically advanced data collection method available to them to gather an accurate representation of vehicle speeds. For state-sponsored speed studies and speed studies performed on a section of roadway that is part of the state trunk highway (STH) network, devices that use radar, laser, and microwave technology as well as pneumatic road tubes are appropriate data collection methods; the stopwatch method shall not be used to collect speed data for these particular studies. The stopwatch method may be used occasionally for speed studies on local roadways and streets by agencies that do not have access to more sophisticated data collection options. Step 3: Analyze Data and Develop Study Conclusions After location-specific data has been collected, it should be analyzed and serve as the basis for study conclusions and recommendations. A report template is available in Attachment A and electronically on the WisDOT Web site at http://dotnet/dtid_bho/extranet/manuals/index.shtm. Based on the data collected in Step 2 and consistent with the report template, state and local speed studies shall analyze the data and report the following study conclusions: • 85th percentile speed. The 85th percentile speed is the speed at or below which 85 percent of the observed traffic travels. The 85th percentile speed has been found to best represent the “reasonable” and “proper” speed perceived by motorists and is a key characteristic of traffic conforming to a “safe” and “reasonable” speed limit. While 15 percent of the observed motorists travel above the perceived “reasonable” and “proper” speed, studies have shown that this group of motorists causes many of the vehicle crashes along roadways. This is also the group at which enforcement action is most effectively targeted. Studies have also indicated that the lowest risk of 14 Wisconsin Statewide Speed Management Guidelines June 2009 being involved in a crash occurs when motorists travel at approximately the 85th percentile speed 6 . • Pace speed. The pace speed is a range of speeds that covers the highest number of observations from the data set. The pace speed shall be generated using a ten-mile per hour range. • 50th percentile speed. The 50th percentile speed (also known as the median speed) is the speed at which 50 percent of the observed traffic traveled at or below that speed. • Design speed of the roadway (if it is known). The design speed is the speed limit for which engineering elements of the roadway were designed to accommodate (e.g. roadway and shoulder width, curve radii, and superelevation). Often times the design speed of state trunk highways is 5 mph higher than the posted speed limit. When the design speed is not known, it can be estimated based on elements of the horizontal and vertical alignment.7 • Speed distribution. Two distribution methods are used to analyze speed data: frequency distribution and cumulative frequency distribution. Frequency distribution compares speed versus the number of observed vehicles traveling at a particular speed. A frequency curve presenting this data will illustrate the modal speed (speed most frequently observed) as well as the pace. Cumulative frequency distribution compares speed to the number of vehicles or percentage of the sample traveling at or less than a particular speed. A cumulative frequency curve presenting this data will illustrate percentile speeds. • Proportion of vehicles exceeding existing speed limit. This statistic reports compliance with the existing posted speed limit and current driver expectation in the proposed speed zone. This data may be useful in building an argument for or against a change to the existing posted speed limit. • Significance of secondary roadway attributes. Attributes such as presence of long turning queues, large volumes of trucks, large volumes of regional traffic, driveways and intersections, sight distance, on-street parking, pedestrian and bicycle activity, as well as pavement condition, level of law enforcement, and divergence between functional classification and practical function play a significant role in driver expectancy and vehicle speeds along a roadway. The analyst should note when secondary roadway attributes are significant and which attributes are present. • Crash data analysis. The speed study conclusions shall also include an analysis of crash data for the past three to five years, indicate if a safety concern exists, and provide the number and percentage of crashes for which speed was a contributing 6 Speed Zoning on Texas Highways. State Department of Highways and Public Transportation, Austin, Texas, 1990. 7 For example, design speed of the curves (an element of horizontal alignment) and stopping sight distance (an element of vertical alignment) are often suitable estimates for overall design speed. 15 Wisconsin Statewide Speed Management Guidelines June 2009 factor. The conclusion shall report a crash rate for the roadway segment being studied, the comparable statewide average 8 , and key contributing factors such as speed, the driver’s physical condition (e.g. chemical impairment, sleeping, age, and seat belt use), weather, and time-of-day the crash occurred. Attachment A includes a copy of the WisDOT speed study data analysis and reporting template. The template is available electronically for use in both state and local speed studies on the WisDOT Web site at https://trust.dot.state.wi.us/extntgtwy/dtid_bho/extranet/manuals/index.shtm . Step 4: Develop Speed Zone Recommendations After vehicle speed and location-specific data has been analyzed, the analyst shall use it to develop and support the speed zone recommendations. It is important for the analyst to note that study conclusions may indicate a speed zone is not needed. A recommendation shall be developed for the speed study indicating whether conditions warrant a need to modify the speed limit of the studied section of roadway. For a change in the speed limit to be effective, it should accomplish the following: • Reduce the speed differential of vehicles using the highway. • Be a reasonable speed so the majority of drivers will comply voluntarily. • Reflect consistent application of traffic engineering principles and guidelines. Decisions regarding the potential change in a speed limit should be based on the objective findings of the speed study and on conditions that exist at the time of the evaluation. Modified speed limits should not be installed to address the following conditions: • Response to noise complaints • Accommodation of specialty vehicles that use the roadway • Future growth anticipated in the area • Anticipated law enforcement of the roadway • Future concerns that have not previously occurred • Correction of spot safety or operational problems. A recommendation shall be made in the speed study that identifies whether the speed limit should change or remain the same. Any recommendation made in the speed study should relate to improving motorist and bystander safety along the route, reference findings from the crash data analysis, and suggest additional study if a safety problem is discovered where speed is not a primary contributing factor. 8 Statewide average crash rates are available at: https://trust.dot.state.wi.us/extntgtwy/dtid_bho/extranet/manuals/hottopics/crash_rates/rate07.pdf 16 Wisconsin Statewide Speed Management Guidelines June 2009 Recommending a Speed Limit Change When the analyst establishes that a modified speed limit should be proposed, the study recommendations shall include two parts: the proposed speed limit and a definition of the proposed speed zone. The process for developing recommendations for each part is outlined below. Setting the Speed Limit When a modified speed limit is proposed as a result of a speed study, several factors shall be considered in the process of developing the speed limit recommendation. • The number of speed limit changes along a route should be minimized and changes should made in significant increments. For speed zones outside of incorporated cities and villages, speed limit changes should be made in increments of 10 mph, though increments of 5 mph are permissible when justified. Within incorporated cities and villages, an increment of 5 mph should be implemented. • The proposed speed limit should be set within 5 mph of the observed 85th percentile speed of free-flowing traffic.9 It is widely accepted that speed limits set at unrealistic levels above or below the 85th percentile speed have little impact on a driver’s choice of speed.10 In addition, the lowest risk of being involved in a crash occurs at approximately the 85th percentile speed.11 12 13 • Highways that serve predominantly regional or statewide traffic, including by-pass highways and roadways on the urban fringe, should have higher speed limits in rural or urbanizing areas than in urban commercial or residential-core areas. These highways should also have speed limits at or closer to the 85th percentile speed as compared to roadways that serve predominantly local traffic. • All recommended modifications to posted speed limits shall be within the range allowable by Wisconsin statute (see Table 1) or shall gain approval from WisDOT. While the 85th percentile speed is a starting point for the speed limit proposal, the analyst should ensure a full range of factors is considered when developing the recommendation. For example, close correlation between design speed, operating speed, and the posted speed limit is desirable. Research also indicates that crash rates go down when posted speed limits are within 10 mph of the mean speed.13 Determining the pace is another valuable tool when considering a speed limit recommendation. A normal distribution curve would include approximately 70 percent of observed vehicles within the pace with approximately 15 percent of observed vehicles below the pace and 15 percent of 9 Manual on Uniform Traffic Control Devices. Federal Highway Administration. Washington, D.C., 2003. Section 2B.13. 10 POLICY RESOLUTION PR-5-93, TITLE: The National Statutory Speed Limit. American Association of State Highway Transportation Officials (AASHTO) Board of Directors. April 19, 1994. 11 Speed Zoning on Texas Highways State Department of Highways and Public Transportation. Austin, Texas, 1990. 12 Speed Zoning Information: A Case of “Majority Rule”. Institute of Transportation Engineers. http://www.ite.org/standards/speed_zoning.pdf. 13 Publication FHWA-RD-98-154: Synthesis of Safety Research Related to Speed and Speed Management. Federal Highway Administration. Washington, D.C., 1998. 17 Wisconsin Statewide Speed Management Guidelines June 2009 observed vehicles above the pace. Typically, the 85th percentile speed is at or near the upper limit of the pace. Several factors other than the posted speed limit influence the 85th percentile free-flow operating speed. These factors include access density, median type, parking along the street, and pedestrian activity level. When the analyst concludes and documents that significant secondary roadway attributes like these exist, the factors may call for a proposed speed limit that is significantly lower (greater than 5 mph) than the 85th percentile speed. The 50th percentile operating speed rounded to the nearest five-mile per hour increment may be a suitable alternate recommendation. However, the analyst should acknowledge that speed limit changes based on secondary roadway attributes rather than observed speeds may have several negative effects, including those listed below: • Higher financial cost due to the need for increased enforcement to ensure driver compliance. • Potential for increased crashes due to larger variability in vehicle speeds. • Mistrust of highway and enforcement officials and potential disregard for other speed limits, because motorists do not readily perceive the need for lower speeds. In this case, the analyst should also recommend that changes to the physical environment accompany the speed limit change as well as consideration of public outreach efforts aimed at reducing speeds using educational and enforcement initiatives. Potential changes to the physical environment range from installation of pedestrian zone or other warning signs to installation of engineering countermeasures including those that modify the roadway itself such as adding sidewalks or consolidating access. A comprehensive discussion of traffic calming measures is available from the Institute of Transportation Engineers (ITE);14 it is generally not recommended to use traffic control devices such as stop signs or traffic signals as tools for controlling speeds. These situations are unique and shall be reviewed by WisDOT Bureau of Highway Operations (BHO) on a case-by-case basis, when WisDOT review is required, to aid in developing consistent, rational speed limit recommendations throughout the state. WisDOT encourages local authorities to review these situations on a case-by-case basis as well and to work toward establishing speed limit consistency for similar circumstances within their jurisdiction. In all cases, speed zoning modifications should be coordinated with adjacent jurisdictions. The process for developing a speed limit recommendation involves many factors and is often complicated. The Federal Highway Administration (FHWA) has developed an expert, Web-based system to aid in the process called USLIMITS 15 , with version 2.0 available without cost as of publication of this document. The application provides a speed limit recommendation after the user inputs location-specific data pertaining to the 14 ITE Traffic Calming Web Site: http://www.ite.org/traffic/ 15 FHWA USLIMITS 2.0: http://www2.uslimits.org 18 Wisconsin Statewide Speed Management Guidelines June 2009 physical environment, speed data, and crash history. Analysts should consider using the tool as a starting point in the development of any revised speed limit recommendation. Defining the Speed Zone The analyst must recommend a physical length for the speed zone in addition to the modified speed limit. It is recommended that the length of the speed zone should be at least 0.3 miles to allow for more uniform and realistic speed limits, especially on roadways that carry large traffic volumes through various roadside conditions or numerous communities. Transitional Speed Zones Generally, it is not recommended to establish transitional or step-down speed zones. Transitional speed zones are typically less than 0.3 miles in length and are intended to provide an opportunity for drivers to step down their speed when approaching zones with lower speed limits. Research suggests that drivers may not reduce their speed to the posted transitional speed limit on the basis of signage alone.16 A transitional zone should be considered if the physical characteristics of the roadway change, such as a rural roadway section with ditches that transitions to a urban section with curb and gutter and minimal driveways and then to an urban section with a significant number of driveways. Transitional zones may also be appropriate in cases where a rural highway enters a community with outlying districts.17 The analyst or agency should consider no more than two transitional zones on a given section of roadway and they should be considered only when the 85th percentile speed shows need for them. Recommending No Speed Limit Change When study conclusions indicate the posted speed limit should not be changed, the analyst/agency should provide alternatives that the responsible jurisdiction can use to respond to the identified issues and concerns, including, but not limited to, noise, specialty vehicles, spot safety problems, or spot operational problems. Alternatives such as traffic calming, roadway design modifications including modifications to roadway cross-section, access control, or other changes to the physical environment may alter vehicle speeds. . A comprehensive discussion of traffic calming measures is available from the Institute of Transportation Engineers (ITE);18 it is generally not recommended to use traffic control devices such as stop signs or traffic signals as tools for controlling speeds. The analyst may want to recommend the completion of additional study as well as consideration of public outreach efforts aimed at reducing speeds using educational and enforcement initiatives. 16 Eric D. Hildebrand, Andrew Ross, and Karen Robichaud. “The Effectiveness of Transitional Speed Zones.” ITE Journal. October 2004. 17 Refer to Wisconsin State Statute 346.57 (1) for the definition of outlying districts. 18 ITE Traffic Calming Web Site: http://www.ite.org/traffic/ 19 Wisconsin Statewide Speed Management Guidelines June 2009 Step 5: Report Draft Results, Conclusions, and Recommendations Each speed study shall be accompanied by a cover letter and worksheets documenting study data, conclusions, and recommendations. A report template is available in Attachment A and electronically on the WisDOT Web site at https://trust.dot.state.wi.us/extntgtwy/dtid_bho/extranet/manuals/index.shtm. These documents supply the reviewer with adequate information about the physical and operational characteristics of the roadway and its surroundings and support a comprehensive review of the speed zone request. In addition to the worksheet and cover letter, the following elements should be included as part of the speed zone request: • Discussion of the reason or reasons for a recommended speed change • A map depicting the limits of the proposed speed zone and the existing speed zone if present • Crash history when it bears on the recommendation • Speed study data to illustrate percentile speeds and the pace (Attachment A includes a copy of the tabulation template that is available electronically on the WisDOT Web site at https://trust.dot.state.wi.us/extntgtwy/dtid_bho/extranet/manuals/index.shtm) • Site photographs of each location where speed readings were taken and, whenever possible, an aerial photograph of the proposed speed zone • Highway photo log files of the proposed speed zone when the change is recommended on a state highway • Documentation of any support or opposition from local units of government, particularly where existing speeds are to be altered The submitting party shall also provide an explanation whenever requested information is omitted. These processes will support the efficient review of and response to recommendations. Step 6: Seek Stakeholder Support After the study’s draft results, conclusions, and recommendations have been developed, WisDOT or the local authority shall share them with primary stakeholders (e.g., WisDOT, including the State Patrol, FHWA, local governments, traffic safety commissions, and local law enforcement). WisDOT or the local authority should take the opportunity to gather feedback and generate support for study findings by presenting results and answering questions from decision-makers about the speed study process. The outreach should include study results, conclusions, and recommendations, as well as the process used to develop the recommendation. 20 Wisconsin Statewide Speed Management Guidelines June 2009 Procedure for Roadways in the State Trunk Highway System The final stages of stakeholder involvement also include gaining required approvals for the recommendations. The approval process for speed limit modifications proposed by WisDOT on the STH system consists of one to three reviews. 1. The region’s approval authority may sign the approval portions of the submittal cover letter and declaration if the recommended speed limit falls within 5 mph of the measured 85th percentile speed and no more than 2 mph below the measured 50th percentile speed, or is increased to the statutory speed limit of the roadway. 2. If the recommended speed limit does not meet these criteria, the region shall submit the cover letter, accompanying worksheets, and any supplemental information identified in Step 5 above to the State Traffic Safety Engineer within the WisDOT Bureau of Highway Operations (BHO), Traffic Engineering Section. The State Traffic Safety Engineer reviews the submittal, consults with the regions regarding questions or clarifications, and may sign the approval portions of the submittal cover letter and declaration if no sensitive recommendations are made. 3. For submittals containing sensitive recommendations, the State Traffic Safety Engineer reviews the findings with the State Traffic Engineer before approval. The WisDOT BHO shall respond to the region in writing with their decision. If a speed zone request is denied, BHO shall provide an explanation of the reasons for denial. Procedure for Other Roadways The approval process for speed limit modifications proposed by local authorities on the local system consists of one to four reviews. Changes proposed within the constraints outlined in Table 1 are subject to the local approval process only and do not require review or approval from WisDOT. It is recommended that the local approval process include legal adoption of the speed zone recommendation through passage of an ordinance. Proposed changes that lie outside the constraints presented in Table 1 shall be reviewed and approved by WisDOT, as outlined above, before legal adoption by local authorities. It is recommended that the local process conclude with the local authority responding to the submitting party in writing, providing notification of approval or an explanation of the reasons for denial. Establishing or Modifying a Speed Zone When results from a speed study show a need for a speed zone or for modification of an existing speed zone and primary stakeholders support and legally adopt the findings, WisDOT or the local authority shall implement the study recommendations. Procedure for Roadways in the State Trunk Highway System When a speed zone request is adopted for an STH, the WisDOT region shall update official records and number the declaration in the following manner: SZ-ww-xxx-yyyy-zz, 21 Wisconsin Statewide Speed Management Guidelines June 2009 where ww is the county number that the roadway resides (e.g., Dane County would be entered 13, Milwaukee County would be entered 40, as illustrated in the example numbering system shown in Attachment B), xxx is the numeric designation of the highway involved in the declaration, yyyy is the four digit year the request was submitted (e.g., 2009), and zz is a number in sequence denoting chronological declarations for the roadway throughout the year, beginning with 01. Procedure for Other Roadways When a speed zone request is adopted for a local road, the local authority should consider cataloging the change and may consider doing so by numbering the approvals in the following manner: SZC-ww-xxxxx-yyyy-zz, where ww is the county number that the roadway resides (e.g., Dane County would be entered 13, Milwaukee County would be entered 40, as illustrated in the example numbering system shown in Attachment B), xxxxx is the letter designation or abbreviated name of the highway/street involved in the declaration,, yyyy is the four digit year the request was submitted (e.g., 2009), and zz is a number in sequence denoting chronological declarations for the roadway throughout the year, beginning with 01. Post Speed Limit Signs Following adoption of recommendations from a traffic engineering-based speed study that includes stakeholder involvement, WisDOT or the local authority should post signs with the modified speed limit as soon as possible. Advance warning features such as fluorescent pink flags or portable changeable message signs may be appropriate to notify motorists of the speed limit change. Monitoring Performance Implementing speed limits on roadways aims to strike a balance between safety and mobility for the traveling public. However, maintaining this relationship requires state and local officials to monitor performance trends within the study area and make changes when appropriate. WisDOT and local authorities should collect data periodically within its speed zones to evaluate whether safety and mobility are being upheld within it. Several performance measures should be considered for comparing before-and-after conditions as well as evaluating trends in the behavior of the traveling public. These measures are summarized below. Performance monitoring is valuable for local speed zones to the maximum extent resources will allow. Compliance. Compliance is the percent of sampled traffic that complies with the posted speed limit. Experts commonly conclude that a speed limit is ‘reasonable’ when 85 percent of sampled traffic travel at or below the posted speed limit. Compliance is a valuable performance measure in before-and-after studies of speed zone implementations. 22 Wisconsin Statewide Speed Management Guidelines June 2009 Speed variance. Speed variance is the frequency distribution of sampled speeds. Experts also conclude that more uniform vehicle speeds reduce the potential for conflict and resulting crashes. Speed variance may also be a significant performance measure in before-and-after studies of speed zone implementations. Crashes by severity. Crashes by severity is the frequency distribution of crashes by their severity. Severity ranges from fatal to injury to property damage only and should be classified as follows: • Fatal – Crashes involving one or more fatalities, or injuries resulting in death within 30 days of the crash. • Injury – Crashes involving or potentially involving injuries, grouped into the following three classes: o Type A – Incapacitating Injury. Crashes where the most severe injuries prevent the injured from walking, driving, or from performing other activities that were common before the crash. o Type B – Non-incapacitating Injury. Crashes where the most severe injuries are not fatal or incapacitating, but are confirmed, or symptoms of the injury confirmed, at the scene. o Type C – Possible Injury. Crashes where injury is claimed by a motorist or suspected by the law enforcement officer, but is not obvious or confirmed at the crash site. • Property Damage Only – Crashes where property damage is the most significant effect. Crash Rate. Crash rate is the number of crashes along a section of roadway per million vehicle miles traveled. Crash rates indicate safety problems by evaluating roadways based on crash frequency, traffic volumes, length of roadway evaluated, and an amount of time the crashes occurred. By using these variables, roadways with different volumes can be compared. However, comparisons must be made carefully as traffic volumes are not the only factor that affects the frequency of crashes on roadways. Crash rate would be useful in monitoring trends following speed zone implementations. Severity Rate.19 Severity rate is an adjusted crash rate that accounts for the severity of a crash. Severity rates present the magnitude of potential safety issues occurring along a stretch of roadway by weighting more severe crashes in the severity rate equation. Like crash rates, though, consideration must be taken when using severity rates as the weighting system of crash severity is subjective and traffic volumes are not the only factor that affects crash frequency along roadways. Severity rate would also be useful in monitoring trends following speed zone implementations. 19 Wisconsin crash severity rate calculation methodology is available at: www.dot.wisconsin.gov/drivers/drivers/traffic/crash/ 23 Attachment A Speed Study Report Template and Worksheet This document is available electronically on the WisDOT Web site at https://trust.dot.state.wi.us/extntgtwy/dtid_bho/extranet/manuals/index.shtm Attachment B Example Wisconsin County Numbering System Example Wisconsin County Numbering System for Tracking Speed Zone Requests County Number County Number Adams 1 Marathon 37 Ashland 2 Marinette 38 Barron 3 Marquette 39 Bayfield 4 Menominee 73 Brown 5 Milwaukee 40 Buffalo 6 Monroe 41 Burnett 7 Oconto 42 Calumet 8 Oneida 43 Chippewa 9 Outagamie 44 Clark 10 Ozaukee 45 Columbia 11 Pepin 46 Crawford 12 Pierce 47 Dane 13 Polk 48 Dodge 14 Portage 49 Door 15 Price 50 Douglas 16 Racine 51 Dunn 17 Richland 52 Eau Claire 18 Rock 53 Florence 19 Rusk 54 Fond du Lac 20 Sauk 55 Forest 21 Sawyer 56 Grant 22 Shawano 57 Green 23 Sheboygan 58 Green Lake 24 St. Croix 59 Iowa 25 Taylor 60 Iron 26 Trempealeau 61 Jackson 27 Vernon 62 Jefferson 28 Vilas 63 Juneau 29 Walworth 64 Kenosha 30 Washburn 65 Kewaunee 31 Washington 66 La Crosse 32 Waukesha 67 Lafayette 33 Waupaca 68 Langlade 34 Waushara 69 Lincoln 35 Winnebago 70 Manitiwoc 36 Wood 71