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Strategy E1. Improve Visibility of Intersections by Providing Enhanced Signing and DelineationNCHRP Report 500 / Volume 5: A Guide for Addressing Unsignalized Intersection Collisions WHERE TO USEUnsignalized intersections that are not clearly visible to approaching motorists, particularly approaching motorists on the major road. The strategy is particularly appropriate for intersections with patterns of rear-end, right-angle, or turning crashes related to lack of driver awareness of the presence of the intersection.
DETAILSMany unsignalized intersections are not readily visible to approaching drivers, particularly drivers on major-road approaches that are not controlled by stop or yield signs. Thus, intersection crashes may occur because approaching drivers may be unaware of the presence of the intersection. The visibility of intersections and, thus, the ability of approaching drivers to perceive them can be enhanced by signing and delineation. Improvements may include advance guide signs, advance street name signs, warning signs, pavement markings, post-mounted delineators, and supplemental beacons on advance signs. The FHWA Older Driver Highway Design Handbook encourages such improvements to contribute to a better driving environment for older drivers. In particular, the handbook addresses advance guide signs and letter height on guide signs as key issues for older drivers. Advance warning signs, such as the standard intersection warning sign, can also alert drivers to the presence of an intersection. Providing a break in pavement markings—including centerlines, lane lines, and edge lines—at intersections also helps to alert drivers to the presence of an intersection. KEY TO SUCCESSSelect a combination of signing and delineation techniques appropriate to conditions on particular unsignalized intersection approaches. This engineering assessment should, where possible, be accompanied by a human factors assessment of signing and delineation needs. Also, the ability and commitment of the highway agency to adequately maintain the signing or delineation is important. ISSUESCare should be taken not to overuse traffic signing, which could result in drivers not perceiving the presence of intersections. TIME FRAME: ShortThis strategy does not require a long development process. Signing and delineation improvements can typically be implemented in 3 months or less. COSTS: LowCosts to implement signing and delineation are relatively low. An agency's maintenance costs may increase. EFFECTIVENESSTRIED: Making drivers aware that they are approaching an intersection, through the use of enhanced signing and delineation, should improve safety at the intersection because drivers will be more alert to potential vehicles on the cross streets. This heightened awareness will quicken drivers' reaction times when conflicts occur. One study concluded that installing double stop signs can reduce all crashes up to 11% and right-angle crashes up to 55%. The same study concluded that installing advance warning signs can reduce all crashes up to 30% at urban locations and 40% at rural locations. Another analysis indicated a crash reduction of 70% when flashing beacons were installed on advance of 3-leg intersections and up to 39% at 4-leg intersections. COMPATIBILITYThis strategy can be used in conjunction with most other strategies for improving safety at unsignalized intersections. SUPPLEMENTAL INFORMATIONSigning in conformance with the Manual on Uniform Traffic Control Devices should be provided. For more details on this and other countermeasures: http://safety.transportation.org For more information contact: FHWA Office of Safety Design FHWA Resource Center – Safety and Design Team 
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Program ContactEd Rice Jeffrey Shaw What’s NewRoundabout Outreach and Education Toolbox Stop-Controlled Intersection Safety: Through Route Activated Warning Systems Roundabouts: An Informational Guide, Second Edition (NCHRP Report 672) Roundabouts Peer-to-Peer Assistance How to drive a roundabout (WSDOT) Modern Roundabouts: A Safer Choice FHWA's Intersection Resources Library CD-ROM HighlightsMini-Roundabouts Technical Summary Access Management in the Vicinity of Intersections Technical Summary Intersection Safety Case Studies Intersection Safety Technologies Presentation: Intersection Safety Example Intersection Safety Implementation Plan |
