Times of Bicycle Crossings

Abstract

The current state of the practice for traffic signal timing does not account for bicyclists in determining the minimum green times or clearance intervals. Like pedestrians, bicyclists need sufficient time to cross an intersection safely. However, this need must be balanced against possible delays for motorist traffic. Accurate estimates of crossing times for bicyclists are thus essential to the safe and efficient design of traffic signals. This paper presents data on bicycle crossing times for different crossing distances near the campus of the University of California at Davis and provides a methodology for measuring bicycle crossing times that other researchers can use. The crossing time and speed data collected for this project can be used to develop guidelines, in conjunction with AASHTO equations, for estimation of minimum green times and clearance intervals as a function of crossing distance. Ten signalized intersections with various motorist and bicycle traffic volumes were videotaped for a total of approximately 11 h. The observed crossing times and calculated speeds for standing, rolling, and quasi-rolling starts are presented. The importance of the physical design of intersections is briefly discussed. Important findings are that the crossing times vary widely for each crossing distance and that the 2nd and 15th percentile speeds are considerably slower than the speeds suggested by AASHTO. These slower speeds may suggest that longer crossing times should be used in signal design to ensure that 98%, or even 85%, of bicyclists will be able to clear an intersection safely.