QUEUE-BASED TRAFFIC-SIGNAL WARRANTS: THE 4Q/6Q WARRANT

Current traffic-signal warrants are based on traffic volumes and accidents. These measures are inflexible. However, a warrant based on queue is sensitive to a wide range of variables, including site geometry and visibility, turning volumes, lane balance, the vehicle, pedestrian and cyclist mix, locations, and speeds. The aim of this feature is to motivate the substitution of the myriad of different volume, accident, and delay warrants with a single warrant based on the observation of queues. Not only is it shown that better and more accurate results can be achieved, but also that the queue warrant is user friendly. The 4Q/6Q warrant justifies a signal if any individual vehicle, pedestrian, or cyclist queue, measured at regular intervals and averaged over the peak hour, is at least four, or if the sum of the individual vehicle, pedestrian, and cyclist queues, measured anywhere within the intersection, exceeds six.