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Why doesn't our city install more traffic signals to help us cross the street?

Traffic signals are an important means of traffic control. When used properly (and where warranted) they can help improve safety, move more cars, and make it easier to cross the street. The number of crashes at an intersection (particularly rear-end crashes) typically increases when traffic signals are installed. This is often due to an increase in vehicles and pedestrians traveling through the intersection after the signal is installed. If the street is relatively narrow and traffic on the cross-street is moderate to low, the signal can result in more pedestrian delay while waiting for the WALK signal. Additionally, some pedestrians may cross against the light and some motorists may run the light, both resulting in more crashes.

Other potential pedestrian crashes may result from right-turn on green or left-turn on green vehicles (when motorists are supposed to yield to a pedestrian in the crosswalk). Improperly placed traffic signals can result in an even higher numbers of crashes, create more traffic congestion and air quality problems, and waste fuel. Traffic signals are expensive to build (costing $100,000 or more to build), operate, and maintain. However, where warranted, traffic signals (with pedestrian signals) can benefit pedestrians in certain situations.

The Manual on Uniform Traffic Control Devices (MUTCD), published by the Federal Highway Administration, provides conditions when the advantages of a traffic signal may outweigh its disadvantages. There are two warrants that specifically or partially apply to pedestrians; the Pedestrian Volume Warrant, and the School Crossing Warrant. In addition, the Crash Experience Warrant may include pedestrian considerations. Satisfying a warrant of a traffic signal shall not in itself require the installation of a traffic signal.

An important consideration in the use of a traffic signal is spacing. When signalized locations are too close together, they could create more congestion, and may create gridlock conditions. In the core of a downtown area, it may be common to have traffic signals spaced one block apart, and traffic progression may be maintained by having one-way streets. In outlying areas, traffic signals should generally be spaced further apart. Because of the high cost of traffic signals and possible negative safety implications, it may be best to evaluate other measures in lieu of a signal, including raised median islands, reducing the number of lanes, improved lighting, improved warning signs or pavement markings. In some cases, it may be wise to divert pedestrians to a nearby traffic signal or consider a grade-separated crossing.