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Federal Highway Administration Research and Technology
Coordinating, Developing, and Delivering Highway Transportation Innovations
| REPORT |
| This report is an archived publication and may contain dated technical, contact, and link information |
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| Publication Number: FHWA-HRT-17-062 Date: May 2018 |
Publication Number: FHWA-HRT-17-062 Date: May 2018 |
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The research documented in this report was conducted as part of the Federal Highway Administration’s (FHWA) Evaluation of Low-Cost Safety Improvements Pooled Fund Study (ELCSI-PFS). FHWA established this PFS in 2005 to conduct research on the effectiveness of the safety improvements identified by the National Cooperative Highway Research Program Report 500 Guides as part of the implementation of the American Association of State Highway and Transportation Officials (AASHTO) Strategic Highway Safety Plan. The ELCSI-PFS studies provide a crash modification factor and benefit–cost economic analysis for each of the targeted safety strategies identified as priorities by the pooled fund member States.
This study evaluated multiple low-cost safety improvements at signalized intersections for basic signing, pavement marking, and signal enhancements. This strategy was intended to reduce the frequency and severity of crashes at signalized intersections by alerting drivers to the presence, type, and configuration of the approaching intersection. The results indicate reductions for all crash types analyzed (i.e., total, fatal and injury, rear-end, right-angle, and nighttime crashes). The economic analysis results suggest that implementation of multiple low-cost treatments at signalized intersections, even with conservative assumptions for cost, service life, and the value of a statistical life, can be cost effective. This report is intended for safety engineers, highway designers, planners, and practitioners at State and local agencies involved with AASHTO Strategic Highway Safety Plan implementation.
Monique R. Evans, P.E., CPM
Director, Office of Safety
Research and Development
Notice
This document is disseminated under the sponsorship of the U.S. Department of Transportation (USDOT) in the interest of information exchange. The U.S. Government assumes no liability for the use of the information contained in this document.
The U.S. Government does not endorse products or manufacturers. Trademarks or manufacturers’ names appear in this report only because they are considered essential to the objective of the document.
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Technical Report Documentation Page
| 1. Report No.
FHWA-HRT-17-062 |
2. Government Accession No.
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3 Recipient's Catalog No.
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| 4. Title and Subtitle
Safety Evaluation of Multiple Strategies at Signalized Intersections |
5. Report Date
May 2018 |
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| 6. Performing Organization Code
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| 7. Author(s)
Thanh Le, Frank Gross, Bhagwant Persaud, Kimberly Eccles, and Jonathan Soika |
8. Performing Organization Report No.
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9. Performing Organization Name and Address
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10. Work Unit No. (TRAIS)
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| 11. Contract or Grant No.
DTFH61-13-D-00001 |
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| 12. Sponsoring Agency Name and Address
U.S. Department of Transportation |
13. Type of Report and Period Covered
Safety Evaluation; October 2010–March 2017 |
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| 14. Sponsoring Agency Code
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| 15. Supplementary Notes
The Federal Highway Administration (FHWA) (Office of Safety Research and Development) managed this study under the Development of Crash Modification Factors program. The FHWA Office of Safety Research and Development Contracting Officer’s Program and Task Manager was Roya Amjadi (HRDS-20). |
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| 16. Abstract
The Development of Crash Modification Factors program conducted safety evaluations of multiple strategies at signalized intersections for the Evaluation of Low Cost Safety Improvements Pooled Fund Study. This study evaluated multiple low-cost treatments at signalized intersections. Improvements included basic signing, pavement marking, and signal enhancements. This strategy was intended to reduce the frequency and severity of crashes at signalized intersections by alerting drivers to the presence, type, and configuration of the approaching intersection. Geometric, traffic, and crash data were obtained at three- and four-legged, two- and four-lane major road, urban, and rural signalized intersections in South Carolina. To account for potential selection bias and regression-to-the-mean, an empirical Bayes before–after analysis was conducted using reference groups of untreated intersections with characteristics similar to the treated sites to develop safety performance functions for the intersection configurations included in this study. The analysis also controlled for changes in traffic volumes over time and time trends in crash counts unrelated to the treatments. The aggregate results indicate reductions for all crash types analyzed (i.e., total, fatal and injury, rear-end, right-angle, and nighttime). The crash modification factors (CMFs) for fatal and injury and right-angle crashes were 0.893 and 0.883, respectively, which were statistically significant at the 95‑percent confidence level. The CMFs for total, rear-end, and nighttime crashes were 0.955, 0.974, and 0.969, respectively, which were not statistically significant at the 95-percent confidence level. Note that the CMF for total crashes was statistically significant at the 90-percent confidence level. The benefit–cost ratio estimated with conservative cost and service life assumptions was 4.1:1 for total crashes at signalized intersections. The results suggest that the implementation of multiple low-cost treatments, even with conservative assumptions on cost, service life, and the value of a statistical life, can be cost effective. |
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| 17. Key Words
Signalized, intersection, low-cost, safety improvements, safety evaluations, empirical Bayesian, before–after, multistrategy, multiple treatments |
18. Distribution Statement
No restrictions. This document is available through the National Technical Information Service, |
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| 19. Security Classification (of this report) Unclassified |
20. Security Classification (of this page) Unclassified |
21. No. of Pages
103 |
22. Price
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| Form DOT F 1700.7 (8-72) | Reproduction of completed page authorized |
