What are the minimum traffic volumes for using multiway stop signs?
As stated in the MUTCD, “Multiway stop control can be useful as a safety measure at intersections if certain traffic conditions exist.” Generally, the traffic volumes for all types of traffic should be about equal. Remember, putting in a multiway stop may actually increase the number of certain types of accidents. Reading the criteria can be confusing, so here is review of the criteria from Section 2B.07 of the MUTCD.
There are several typical uses:
- As an interim measure until traffic control signals can be placed.
- When there is evidence of 5 or more crashes each year which might be corrected by the use of multiway stop signs. These include turning and right-angle collisions.
- When the traffic volumes warrant the use of multiway stop signs. The volume for the busiest eight hours during the day should be used. These may not be continuous. In many cases, the busiest eight hours may include several hours in the morning and several in the evening. The minimum volumes for the busiest eight hours are:
- Major road: Vehicle volumes of at least 300 vehicles per hour approaching from both directions for any eight hours, AND
- Minor road: Combined vehicle, bicycle, and pedestrian volumes of at least 200 vehicles per hour approaching from both directions for any eight hours.
- In addition, during the busiest hour the average delay for VEHICLES is at least 30 seconds on average.
If the 85th-percentile approach speed on the major road exceeds 40 mph (in a free flowing area approaching the stop sign location), then the minimum volumes are:
- Major road: Vehicle volumes of at least 210 vehicles per hour approaching from both directions for any eight hours, AND
- Minor road: Combined vehicle, bicycle, and pedestrian volumes of at least 140 vehicles per hour approaching from both directions for any eight hours
- In addition, during the busiest hour the average delay for VEHICLES is still at least 30 seconds on average.
If the number of crashes is only 4 per year, then the volume criteria should be examined. In this case, the volumes should be:
- Major road: Vehicle volumes of at least 240 vehicles per hour approaching from both directions for any eight hours, AND
- Minor road: Combined vehicle, bicycle, and pedestrian volumes of at least 160 vehicles per hour approaching from both directions for any eight hours
- In addition, during the busiest hour the average delay for VEHICLES is still at least 30 seconds on average.
There are several additional criteria that may warrant the use of a multiway stop sign even if the criteria above are not met. These include: left turn conflicts, vehicle pedestrian conflicts, sight distance issues, and traffic flow in residential areas. In any case, engineering judgment must be used for any sign application. If the number of legs is not four, then a detailed engineering study is a good idea to be sure the multiway stop signs will work. It is also a good idea to come back after a month or two to see how the intersection is flowing. Be sure the new signs are doing the job they are supposed to do.
The precise wording can be found in section 2B.07 of the National MUTCD. The NYS Supplement makes no modifications to section 2B.07, so the National MUTCD should be followed:
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