Date post: | 17-Jan-2016 |
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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: [email protected]
Ed RiceOffice of Safety (HSSD)Federal Highway Administration
Phone: (202) 366-9064E-mail: [email protected]