When residents perceive a traffic signal to be the solution to operational and safety problems at an intersection, remind them of this: having a signal where one isn’t necessary can be more dangerous than not having one at all. When an unwarranted signal is installed at an intersection, you could see an increase in:

• rear-end collisions


• traffic delays/congestion


• fuel consumption and pollution


• wear and tear on vehicles


• driver frustration


• use of alternate routes not designed for heavy traffic

Traffic signals also cost money to install, operate, and maintain. Often, lesser forms of traffic control, such as stop signs or traffic calming measures, can achieve the desired results at a lower cost.

When other forms of traffic control prove to be ineffective, a traffic signal may be the only solution. However, to determine the need for a signal, traffic engineers must carefully evaluate the intersection using very specific guidelines set forth by the Federal Highway Administration. Some of the criteria used include:

• intersection collision history


• number of vehicles using the intersection


• pedestrian and bicycle activity


• speed limit


• other signals in the area


• intersection characteristics, including visibility


• type of area (i.e., residential, industrial, school zone)


• other potential impacts the signal might have

So, the next time you hear someone say “we need a light at that intersection,” consider the pros and cons and recognize that there are alternative solutions that may be just as effective.