Intersection Safety Case Study Summary

FHWA-SA-09-014

Red-Light Running:All-Red Clearance Intervals and Larger Signal Lenses

A Michigan Success Story

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The Challenge

• Red-light running causes more than 170,000 injuries and 900 deaths per year1.

• Driver speeding and distracted driving, as well as inability to see the traffic control device in time to comply are common problems.

• Clearance intervals, together with increasing the size of the signal lenses, have been shown to improve intersection safety.

• Cities of Detroit and Highland Park sought simple, low-cost safety treatments to increase driver compliance with traffic signals, and reduce the number and severity of crashes at urban signalized intersections.

1. Federal Highway Administration Red-Light Running Web Site (2008), http://safety.fhwa.dot.gov/intersection/redlight/.

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Solution

All-red interval and larger signal lens:• Replace red, yellow, and green 8-inch signal

lens with 12-inch signal lens • Added an all-red clearance interval ranging

from 1-2 seconds2

2. Calculated using Institute of Transportation Engineers (ITE) guidelines.

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Technical Data

• Location:– 33 high-crash locations in the cities of Detroit and Highland Park, Michigan

• Speed Limits:– Ranged from 35 mph to 40 mph

• Implementation Cost:– Total corridor cost of $2.3 million at $70,000 per intersection

• Implementation Time:– 6 months

• Implementation Issues:– The cities experienced no implementation issues with these countermeasures

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Results at Treated Intersections

• Average Crash Reductions:– 75.7% reduction in angle crashes per year– 45.5% reduction in injury crashes per year– 33.3% reduction in total crashes per year

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• Visit FHWA’s intersection safety web site to download this and other case studies highlighting proven intersection safety treatments from across the country:

http://safety.fhwa.dot.gov/intersections/

• Or contact:

For More Information

Tapan DattaTransportation Research GroupWayne State University

Phone: (313) 577-9154E-mail: tdatta@eng.wayne.edu

Ed RiceOffice of Safety (HSSD)Federal Highway Administration

Phone: (202) 366-9064E-mail: ed.rice@dot.gov