Traffic signals should be installed when they will alleviate more problems than they will create. This must be determined on the basis of an engineering study.
Warranted Traffic Signals
A warranted traffic signal which is properly located and operated may provide for more orderly movement of traffic, and may reduce the occurrence of certain types of accidents. On the other hand, an unwarranted traffic signal can result in increased delay, congestion, and accidents.
Traffic Signal Issues
Many people seem to believe that traffic signals are the answer to all traffic problems at intersections. If this were true, no traffic engineer in his right mind would deny a request for a signal.
However, a traffic signal only functions by stopping traffic, and any time a motor vehicle is stopped in the road a potential accident is created. It does not matter whether the stop is caused by a flat tire, a left turn into a driveway, or by a traffic signal, the possibility exists that the motorist who is following will not notice the stopped vehicle until it is too late.
What traveler has not experienced that sickening feeling that occurs when a traffic signal suddenly turns amber a few hundred feet in front of him? Who has not experienced the aggravating hopelessness of waiting in a long line of cars for a traffic signal to change, moving ahead a few feet, and then having the signal turn red again?