Traffic signals don't always prevent collisions. Typically, when a signal is installed, the total number of crashes increases, but the severity decreases. Where signals are used, the most common result is a reduction in right-angle collisions, however, rear-end crashes are prone to show an increase. Signals also may give pedestrians a false sense of security.

Traffic signals are intended to facilitate the orderly movement of traffic. As the most restrictive form of traffic control, traffic signals are installed only where less restrictive signs or markings do not provide a sufficient level of control. Most intersections would not necessarily be improved or made safer by the installation of a traffic signal. Unnecessary signals cause wasteful and annoying delays to the flow of traffic. They can increase traffic on the side streets as drivers seek alternative routes through neighborhoods. Excessive starting and stopping burns needless amounts of gasoline, resulting in pollution and economic loss. And as previously mentioned, they can increase the total amount of crashes at an intersection.

The Columbus Consolidated Government follows City policies and Georgia State Law, which requires us to follow the national guidelines outlined in the Manual on Uniform Traffic Control Devices (MUTCD) . Traffic control devices include signal lights, traffic signs and markings. The MUTCD covers all aspects on the placement, construction and maintenance of every form of approved traffic control.

In determining the need for signalization, traffic engineers ask several standard questions about the intersection.