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HomeMy WebLinkAboutNB 5 TRAF SIG WARRANT 01-15-90F DATE: TO: FROM: SUBJECT: JANUARY 8, 1990 WILLIAM HUSTON) CITY MANAGER NEW�_BUSINESS N0. 5 1-15-90 1 Inter - Com DEPARTMENT OF PUBLIC WORKS/ENGINEERING DIVISION FOLLOW-UP TRAFFIC SIGNAL WARRANT ANALYSIS - BRYAN AT FARMINGTON RECOMMENDATION That the Tustin City Council at their regular meeting of January 15, 1990, approve the installation of a traffic signal at the intersection of Bryan Avenue and Farmington Road and direct staff to include this item in the upcoming 1990-91 Capital Improvement Budget. BACKGROUND Pursuant to a City Council request early in 1989, staff evaluated the subject intersection insofar as traffic signal warrants were concerned. In mid -1989, another evaluation was performed to review any changes in vehicular volumes or accidents where the need for a signal could also change. While the evaluation at that time resulted in a recommendation not to install the signal, a six month follow-up to that issue was requested. This report and analysis fulfills that request as described below. DISCUSSION Bryan Avenue at the intersection of Farmington Road is stop sign controlled. Also, there is an existing school crosswalk which crosses Bryan Avenue on the west side of the street. The speed limits on each are 40 mph for Bryan Avenue and 25 mph for Farmington Road. To determine the need for a signal, detailed analyses were conducted of all factors that could lead to the decision to install the device. In total, eight different elements (traffic signal warrants) were reviewed and include the following: (1) The volume of intersecting traffic and their affect on one another. (2) The affect of major street traffic on the ability of side street traffic to access the major street. (3) The volume of pedestrian crossings. (4) The need for extraordinary school area traffic control. (5) The affect of a Farmington Road signal on the progressive movement of Bryan Avenue traffic. (6) An analysis of existing accidents as well as traffic accidents that could theoretically occur after the signal was constructed. (7) The need to "organize" the system of signals between the westerly Bryan Avenue signal at Red Hill and the new easterly signal at Browning. (8) Traffic conditions during only the peak morning and/or afternoon travel periods (i.e. peak hour volume levels and/or delay). Signal Analysis page 2 Our evaluation also included a review of the existing stop sign operation at the intersection. Recognizing that the installation cost of a signal is about $100,000, with about $300 a month for on-going maintenance and electrical needs, the benefits of maintaining the stop condition as is were evaluated. Our current evaluation, presented by this report, shows that a traffic signal at Bryan Avenue and Farmington Road is marginally warranted. Of the eight different signal warrants for this intersection, two are fully satisfied. These include both the "Progressive Movement" and the "Systems Warrant" (i.e. will the new signal keep traffic moving within the influence area of the existing easterly and westerly signalized intersections?). Other warranting criteria which involve the level of existing traffic (i.e. the "Minimum Vehicular Volume" warrant and the "Interruption of Continuous Traffic" warrant) are not satisfied at this time. However, should a signal be installed at Bryan and Farmington, it could attract more traffic from nearby Bryan Avenue intersections (such as Stonehenge) to where minimum warrant values would be met. The same reasoning can be applied to another warrant termed the "Peak Hour Volume" warrant. While current volume levels fall short of its minimum warrant satisfaction values, new traffic would be attracted to the intersection. Therefore, the resulting values would be such where the margin boundary of a signal being needed could be reached. The accident history of the intersections is very good. Our records show that with the exception of 1988, there has been one stop sign related accident per year. In 1988, there were two accidents. Although a traffic signal will create different kinds of accidents over those occurring at stop signs, we expect that a similar number of accidents will occur if the signal is installed. It should be noted however that, because of "green light" conditions prior to accidents, future accidents will probably be more severe due to higher speeds. The greatest advantage of a signal at Bryan and Farmington would be to reduce vehicular delay along Bryan Avenue. Aside from the signal's cost, a disadvantage would be a probable increase in delay to traffic on Farmington. The reason is that left turning traffic from Farmington could no longer take advantage of gaps in Bryan Avenue traffic to enter the roadway. Also, depending on the level of traffic on Bryan, drivers wishing to turn right from Farmington to Bryan could also be delayed over that which is current. Since the accident history is good now and would probably remain so even after the signal were available, a signal would not be advantageous from an accident reduction point of view.