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FHWA Home / Safety / Intersection / Strategy E8. Provide Supplementary Stop Signs Mounted Over the Roadway

Strategy E8. Provide Supplementary Stop Signs Mounted Over the Roadway

NCHRP Report 500 / Volume 5: A Guide for Addressing Unsignalized Intersection Collisions

WHERE TO USE

Unsignalized intersections with patterns of right-angle crashes related to lack of driver awareness of the presence of the intersection. In particular, it might be appropriate to use this strategy at the first stop-controlled approach (possibly of a series) located on a long stretch of highway without any required stops, or at an intersection located after a sharp horizontal curve.

Photograph of STOP signs mounted on both a post and the mast arm it supports above a roadway.
Photo by: Texas Transportation Institute

DETAILS

Many stop signs at stop-controlled intersections are not readily visible to approaching drivers due to geometric conditions, presence of vegetation, or other objects (such as tall vehicles) that can limit the view of the regular stop signs. Thus, intersection crashes may occur because approaching drivers may be unaware of the presence of the stop sign at the intersection. The visibility of stop signs and, thus, the ability of approaching drivers to perceive them, can be enhanced by providing supplementary stop signs suspended over the roadway.

The target for this strategy should be stop signs at intersections that are not clearly visible to approaching motorists, particularly approaching motorists on the minor road. The strategy is particularly appropriate for intersections with patterns of rear-end, right-angle, or turning collisions related to lack of driver awareness of the presence of the intersection or stop sign.

KEY TO SUCCESS

Locate the supplementary overhead sign (or signs) in the direct line of sight of approaching drivers.

ISSUES

Unless the signs are mounted on existing overhead structures (mast arms), additional hardware will have to be placed on the roadside, which could become an additional object that a vehicle may strike if it leaves the roadway.

TIME FRAME: Short

This strategy does not require a long development process and can typically be implemented in 3 months or less.

COSTS: Low

The costs involved in providing supplementary overhead stop signs are minimal when the signs are mounted on existing structures. The additional cost of providing a mast arm is moderate. Agencies may experience additional maintenance costs.

EFFECTIVENESS

TRIED: The safety effectiveness of providing supplementary stop signs mounted over the roadway has not been quantified.

COMPATIBILITY

This strategy can be used in conjunction with most other strategies for improving safety at unsignalized intersections.

SUPPLEMENTAL INFORMATION

Supplementary signs should be in accordance with the MUTCD.

For more details on this and other countermeasures: http://safety.transportation.org



For more information contact:

FHWA Office of Safety Design
E71, 1200 New Jersey Avenue SE
Washington, D.C. 20590
(202) 366-9064
http://safety.fhwa.dot.gov

FHWA Resource Center – Safety and Design Team
19900 Governor's Drive, Suite 301
Olympia Fields, IL 60461
(708) 283-3545
https://www.fhwa.dot.gov/resourcecenter

Logo for FHWA and logo for the FHWA Office of Safety, which reads 'Safe Roads for a Safer Future – Investment in roadway safety saves lives.'

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Page last modified on September 4, 2014.
Safe Roads for a Safer Future - Investment in roadway safety saves lives
Federal Highway Administration | 1200 New Jersey Avenue, SE | Washington, DC 20590 | 202-366-4000