Traffic Signals

Traffic signals are familiar to everyone. While stop signs at intersections fix which direction of traffic will have the right-of-way, traffic signals can vary the direction and even the individual turning movement that will have right-of-way.

Traffic signals can be beneficial in managing traffic since they can provide nearly equal service to each approach at an intersection. On busy roadway corridors, however, too many signals can create significant disruption where once there may have been smooth flow. In addition to driver delay, disruption in traffic flow can cause an increase in rear-end collisions and exhaust emissions. Traffic signals installed at inappropriate locations are frequently abused and may create a false sense of security, particularly for pedestrians. 

A national standard has been developed whereby the warrant for signalization of an intersection can be calculated. The methodology calculates a number of ‘priority points' based on such factors as traffic and pedestrian volumes, accident history, and the location of other nearby traffic signals. A total of 100 or more priority points is an indication that signalization of an intersection is warranted.

Our practice is to signalize only those intersections which achieve 100 or more priority points. The number of locations that we can signalize is limited both by fiscal resources and the interruption to traffic flow that is created. Using the signal warrant calculation, we can be sure that signalization is implemented where it is most beneficial and appropriate.