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Warrants For Traffic Control Devices
The following information was provided by the Traffic Improvement Association (TIA).
A Warrant for any traffic control device (sign, signal or pavement marking) is the minimum criteria that must be met before such a device can be installed. Meeting a warrant does not mean a traffic control device must be installed. The Michigan Manual of Uniform Traffic Control Devices spells out these warrants to ensure that each device:
- Fulfills a need
- Commands attention
- Conveys a clear, simple meaning
- Commands respect
- Gives adequate time for proper response
Traffic Signals & Stop Signs
Traffic signals have eleven Warrants, at least one of which must be met before a signal can be installed. These Warrants state the number of vehicles, pedestrians, crashes or a combination of these that must exist before a signal can be installed. Stop signs have their own set of four Warrants:
- Intersection of a less important road with a main road where the normal right-of-way rule is unduly hazardous,
- Street entering a through highway or street.
- Unsignalized intersection in a signalized area, or
- Other intersections where a combination of high speed, restricted view, and serious crash record indicates a need for control by the Stop sign.
Less Restrictive Measures
Prior to the application of these Stop sign Warrants, consideration should be given to less restrictive measures, such as a Yield sign. There are also specific Warrants for warning signs (Curve Ahead, School Crossing, Construction Zone, etc.), paint markings (crosswalks, lane lines, pavement edge markings, etc.)
Any devices that are not in the Manual are not traffic controls and cannot be used. These include Slow Children and Slow signs. In addition to meeting the Warrants, regulatory signs (Stop, Speed Limits, Parking, etc.) must also have an official Traffic Control Order signed by the Traffic Engineer and filed with the local clerk.
The decision to install a traffic control device should be made on the basis of an engineering study, the Warrants and engineering judgments by a qualified traffic engineer. Effective and safe traffic control depends on the appropriate application of traffic control devices and reasonable law enforcement. These Warrants are based on that concept.