In order to assure traffic signals are installed only where necessary, a series of 11 warrants have been developed and accepted by traffic engineers throughout the country.

Traffic signal warrants are contained in a manual developed by the U.S. Department of Transportation, entitled "Manual on Uniform Traffic Control Devices" (MUTCD).

For State approval, a signal must meet at least one of the warrants presented in the MUTCD.

A summary of the 11 Warrants for Traffic Signals is presented in the following table.

1. Minimum Vehicular 500 to 650 150 to 200 Volume, (depends on number of lanes).

2. Interruption of Continuous 750 to 900 75 to 100 Traffic (depends on number of lanes).

3. Minimum Pedestrian Volume 600 or more plus 150 or more pedestrians crossing streets.

4. School Crossing insufficient number of adequate gaps to allow children to cross.

5. Progressive Movement to maintain proper vehicle grouping between successive signals.

6. Accident Experience five or more accidents susceptible to correction by signal control
    within a 12 month period.

7. Systems two major streets 800.

8. Combination of Warrants 80% of two of the first three warrants.

9. Four Hour Volumes see MUTCD graph see MUTCD graph

10. Peak Hour Delay see MUTCD graph see MUTCD graph

11. Peak Hour Volume see MUTCD graph see MUTCD graph

      (1) Need not be eight consecutive hours, but must represent the same hours for the
            major and minor streets.

SOURCE: Adapted from Manual on Uniform Traffic Control Devices,
(MUTCD) 1978 by the U.S. Department of Transportation.