The placement of traffic signals is based on traffic studies and analysis conducted by the city's traffic engineering team. Staff has compiled a Traffic Signal Priority List, or TSPL, which ranks intersections that have been or are currently being considered for new traffic signal installation.
In general, consideration factors include traffic volume, accident history, and pedestrian activity. Discussions often precede the decision to install a new traffic signal. The Manual on Uniform Traffic Control Devices (MUTCD) lists different ways that a traffic signal can be “justified.” These nine different ways will be called “criteria” in this report. In the MUTCD, the criteria are called warrants. Regardless of the terminology, the nine criteria provide a nationally used, systematic method to evaluate the need for traffic signals. Meeting just one of these criteria can be justification for installing signals. However, many other factors need to be considered.
Addressing travel needs by alternative means without installing signals may be desirable at some locations even when one or more of the signal criteria are met. The City Traffic Engineering Division will use the nine criteria published as warrants in the MUTCD. Traffic will be counted, typically by automatic machine methods that segregate traffic for each approach. Locations that appear close to meeting one or more criteria will receive more intense study, including manual counts that segregate traffic by type (motor vehicle, bicycle, pedestrian) and movement (left turn, right turn, straight through); vehicle delay study; field review of existing intersection conditions; etc. A rank order priority list will be prepared for review by the Transportation Commission. Staff will prepare commentary on those intersections of most interest to the Commission. The commentary will cover special consideration items listed earlier and other issues. If a new traffic signal installation is recommended, then the city will determine how to pay for the design and construction of the traffic signal including the creation of an assessment district.
