Turner-Fairbank Highway Research Center

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Comparison of the Safety of Lighting Options on Urban Freeway

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HSIS Summary Report


Michael S. Griffith




This paper compares the safety of continuously lighted urban freeways and urban freeways with interchange lighting only. A total of 87.9 km (54.6 mi) of urban freeway segments with continuous lighting and 57.1 km (35.5 mi) with interchange lighting only were used in the study. All of the study sections were in the Minneapolis-St. Paul metropolitan area. The total night/day crash-rate ratio for the sections with interchange lighting only was 12 percent higher than the total night/day crash-rate ratio for sections with continuous lighting. The night/day crash-rate ratio for non-interchange areas was 18 percent higher for sections with interchange lighting only than for continuously lighted sections. The night/day crash-cost ratio for freeway sections between interchange areas without overhead lighting was calculated to be 27 percent higher than that for freeway sections between interchange areas with overhead lighting. The benefit/cost ratio of continuous lighting for the study's 22 miles of urban freeways between interchange areas is 3.7. The estimated economic benefit is $7.3 million.

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Urban freeways
Crash costs

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