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HomeMy WebLinkAboutTRA_StaffMemo_May 2011TRAFFIC REVIEW ADVISORY BOARD AGENDA ITEMS MAY 2011 NEW BUSINESS 1. 2010 ACCIDENT ANALYSIS You will find, attached to this staff memorandum, my report on high-crash locations during 2010. Since the accident analysis has typically looked at traffic control methods of improving safety, this year’s high crash locations have been analyzed by the type of existing traffic control. This report also includes an analysis of crash experience at the City’s four roundabouts. 2. A DISCUSSION OF THE INTERSECTION OF KOELLER STREET AND 20TH AVENUE. This is a Board member request. The reconstruction of the 9th Avenue overpass over Highway 41 has appeared to divert some traffic to use the 20th Avenue overpass and the STH 44 interchange instead. One of the traffic movements which seems to have experienced more traffic is the southbound right-turn movement at the intersection of Koeller Street and 20th Avenue, for which there is no dedicated turn lane. Consequently, right-turning vehicles, which might be able to turn on red, may be blocked by vehicles traveling straight. A Board member expressed interest in seeing whether having a dedicated right turn lane might be a more efficient use of the existing lane than its current shared use. This idea is shown in Figure 1.  Figure 1: Existing and Proposed Lane Configurations for Southbound Koeller Street at Its Intersection with 20th Avenue  Figure 2: PM Peak Hour Traffic Volumes, Koeller Street and 20th Avenue, April 2010 To analyze this proposal, turning movement data were collected during the last week in April, while the 9th Avenue overpass construction activity was continuing. Peak hour counts are provided in Figure 2. This intersection was analyzed using our traffic analysis software to see what impact this might have on delay at the intersection. The intersection was analyzed based on its current signal timing pattern, which is a pre-timed pattern that includes protected left-turns for all traffic approaches. The results of this analysis for PM peak hour traffic volumes are shown in Table 1. The table shows the average delay per vehicle (in seconds) for each approach to the intersection, along with the corresponding level of service (LOS). LOS is a qualitative measure that helps to assess the relative quality of traffic operations. The level of service is assigned on an A through F scale, with A signifying free flow conditions, and F signifying a breakdown in flow. Typically, the goal is to attain a level of service of D or better. Table 1: Estimated Average Delay (in seconds) and Level of Service (LOS) at the Intersection of Koeller Street and 20th Avenue (PM Peak Period)  The analysis indicates that the average delay for the intersection would not change significantly, although it would increase for southbound traffic. The increase is likely the result of there being more southbound through traffic than southbound right-turning traffic. Making a change like this would involve changing signage and pavement markings. There would also be an adjustment process, as motorists would need to acclimate to the new lane pattern. Another consideration is that this request would introduce a “trap lane”. A trap lane is a lane on a multi-lane road which becomes a turn-only (left or right) lane at the intersection. Since many Oshkosh streets have limited right-of-way, this phenomenon exists at several locations in the City, such as southbound Oregon Street approaching 6th Avenue, eastbound Murdock Avenue at Bowen Street, and 9th Avenue approaching Knapp Street. Trap lanes can encourage abrupt lane changes, and are therefore typically discouraged unless warranted by traffic volumes. This might be compounded by traffic exiting from Oshkosh Center (the shopping center at the northwest corner of the intersection) to continue south on Koeller Street. Given that the intersection operates at an acceptable level of service and that implementing the request could introduce some new problems, I think it is better to leave this intersection as is. STAFF STATEMENTS 3. NEIGHBORHOOD PARKING ISSUES ON FAIRFAX DRIVE AND PHEASANT CREEK DRIVE At the last couple of meetings, there has been an agenda item related to restricting parking on Fairfax Drive. It sounds like police involvement may have mediated a solution to this. Therefore, at staff recommendation, the proposed parking restrictions will be tabled. If it turns out the solution is not working, this item will be on the Board’s agenda for its June meeting.