The City of Richardson follows internationally recognized best practices for setting traffic signal clearance times for vehicles and pedestrians.
Vehicle clearance times include both the duration of the Yellow light and an All-Red period after the Yellow but before any conflicting Green. The policy since 1986 has been that each green light must be followed by a yellow clearance interval which warns approaching drivers that the right-of-way is about to be reassigned to a conflicting movement. The yellow interval is followed by an all-red period that allows vehicles that have entered the intersection to clear the intersection before the opposing movement is given the green light. These intervals are set using intersection geometrics and vehicle speeds. By basing criteria on the intersection conditions, we achieve the following goals: clearance time consistency, increased safety, increased intersection capacity, and improved overall intersection efficiency. The City’s programmed Yellow times and policies were not changed as any part of the implementation of the Police Red Light Photo Enforcement Program.
Pedestrian Clearance times include both the Walk (White Walking Man) and the Flashing Don’t Walk (Flashing Red Hand) and are set according the recommendations and requirements of the Texas Manual of Uniform Traffic Control Devices (TMUTCD) and the American with Disabilities Act Access Guidelines (ADAAG). At some signalized locations, where the vehicle green time is long enough, the Walk time is programmed to appear every time the vehicles get the green light. At most locations, a pedestrian must push the button provided on the signal pole to request the Walk time. The Walk will then appear at the next opportunity when the corresponding vehicle movement is green. This also extends the corresponding vehicle green time. The Walk indication is displayed for a brief period intended for waiting pedestrians to notice the indication has changed, and to start crossing the street (usually 5-6 seconds). The signal then changes to the Flashing Don’t Walk. The Flashing Don’t Walk symbol lets people about to cross the street know that they don’t have enough time left to start crossing. The countdown timer beside the Flashing Don’t Walk hand lets pedestrians already in the crosswalk know how much protected time they have left to finish crossing the street. Most of the City’s Flashing Don’t Walk times are set according to the standard of a 4 foot per second crossing speed. The City has started using the more conservative 3.5 foot per second speed requested by the ADAAG at some locations.