Operational Guidance For Bicycle-SpecificTraffic Signals in the United States: A Review

1 INTRODUCTION The purpose of this report is to summarize the relevant design and related guidance for bicycle-specific traffic signals, the existing published literature, and the results of a survey of installed bicycle-specific traffic signals in North America. This interim report contains the following four chapters:  Background – A summary of relevant design manuals, legislation, and policy.  Literature Review – A synthesis of published literature related to bicycle-specific traffic signals.  State of the Practice – A summary of our survey of known installations of bicycle-specific traffic signals, mostly in the U.S. but with a handful of Canadian jurisdictions.  Research Needs – Based on the results of the above reviews, a discussion of the identified research needs. 2 2 BACKGROUND This chapter briefly reviews the relevant design manuals, engineering documents, and enabling legislations. These are provided as context for the subsequent chapters. The review includes both versions of the AASHTO Guide for the Development of Bicycle Facilities. The American Association of State Highway and Transportation Officials' [AASHTO] 1999 Guide for the Development of Bicycle Facilities recognizes that the greatest risk for cyclists at an intersection is when crossing. This is especially so during periods of low traffic flow at actuated signals where the minimum clearance interval for waiting cars may be inadequate for cyclists entering during the yellow phase. From the Guide, equations for the minimum clearance interval are as follows: It should be noted that for many intersection widths, this formula produces very long yellow and red clearance intervals. Cyclists starting from a stopped position require a minimum total phase time in order to perform a complete crossing maneuver including reacting to the new green signal and accelerating from stop. After establishing minimum yellow and all-red intervals, a minimum green time is needed to ensure most cyclists can safely cross an intersection from a stopped position. Equations for the minimum green time from the Guide are as follows: 3 Figure 2-2 Minimum Green Time Equations (AASHTO, 1999) In lieu of field data from actual cyclists at the intersection to be timed, the AASHTO's Guide uses three classes of cyclist to estimate cyclist speed for use in the above equations. The three categories of " design " cyclists were originally established in a Federal Highway Administration [FHWA] report on accommodating bicycles on roadways (1994). The FHWA and AASHTO define the classes A, B, and C as follows: …