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FHWA Home / Safety / Intersection / Low-Cost Safety Enhancements for Stop-Controlled and Signalized Intersections

Low-Cost Safety Enhancements for Stop-Controlled and Signalized Intersections

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6. Speed Reduction Countermeasures on High-Speed Approaches to Intersections

Crash Problem

Intersection approaches where drivers commonly enter the intersection at excessive speeds can potentially increase the severity of crashes. In addition, higher approach speeds may make it more difficult for some stopped drivers at stop-controlled intersections to identify safe gaps to enter the intersection. Another concern is intersections with high speeds on the through approaches and limited available sight distance from the stop approach.

Countermeasures

The countermeasures are primarily intended for consideration on the through approaches at stopcontrolled intersections. However, they may also be considered, after careful analyses, for high-speed approaches at signalized intersections. Minimal information is available concerning the crash reduction factors for speed reduction countermeasures. A number of countermeasures have performed well under limited levels of deployment. However, additional deployments may yield different results. These countermeasures may be cautiously deployed and complemented with evaluations to determine if the desired results have or have not been obtained.

The low-cost countermeasures for intersections with a high frequency of high-speed vehicle crashes on approaches include a number of options, as follows:

Photo depicting a T intersection. The roadway on the arms of the T are treated with grooves parallel to the edge lines and pavement markings to the left of each travel lane that narrow the roadway in both directions along the approach to the intersection. Circles highlight the grooved areas and pavement markings.
Figure 6: Lane Narrowing Using Rumble Strips

Countermeasure Crash Reduction Factors, Threshold Levels, Additional Implementation Factors, and Estimated Cost Ranges

Crash reduction factors based upon limited research, typical crash thresholds for application considerations, and additional intersection concerns that need to be addressed for each of the countermeasures are provided in Table 6.

Table 6: Crash Reduction Factors, Typical Crash Thresholds, Additional Application Factors, and Estimated Implementation Cost Ranges for Countermeasures at Stop-Controlled Intersections with High-Speed Approaches
Countermeasure Crash Reduction Factor Typical Urban Crash Threshold Typical Rural Crash Threshold Additional Intersection Concern Implementation Cost Range per Intersection
Lane narrowing using pavement marking and shoulder rumble strips 31% 10 speed-related crashes in 5 years 5 speed-related crashes in 5 years Free of noise and bicycle issues-single through lane $20,000 to $40,000
Lane narrowing using pavement marking and raised pavement markers Unknown but probably less than 31% 10 speed-related crashes in 5 years 5 speed-related crashes in 5 years Single through lane $5,000 to $10,000
Peripheral Transverse pavement markings Unknown 10 speed-related crashes in 5 years 5 speed-related crashes in 5 years  $3,000 to $5,000
Dynamic speed warning sign to reduce speed 30% 10 speed-related crashes in five years 5 speed-related crashes in 5 years  $10,000
Slow pavement markings Unknown 10 speed-related crashes in 5 years 5 speed-related crashes in 5 years  $2,000 to $5,000
High-Friction Surface 25% (All crashes) 10 speed-related crashes in 5 years 5 speed-related crashes in 5 years  $20,00 to $50,000


Except for the high-friction surface countermeasure, countermeasures should be considered as singular treatments with the selection of the countermeasure based upon specific intersection characteristics, crash types and frequencies, costs, and crash reduction factors. The high-friction surface countermeasure may be combined with other countermeasures to yield more effective results.

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Page last modified on September 4, 2014.
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