Knowledge Base

Traffic engineers follow the national standards described in the Manual on Uniform Traffic Control Devices (MUTCD). The MUTCD mandates that a traffic signal cannot be installed unless the intersection has met the requirements of one or more traffic signal “warrants.” These warrants consider various criteria when evaluating the intersection, such as vehicle volumes, pedestrian volumes, and crash history.

Traffic signals can improve traffic flow and increase safety when used properly. However, traffic signals are not always the right solution and do not always prevent accidents. For example, a traffic signal may reduce the number of right-angle collisions at an intersection, but the number of rear-end crashes may increase.