U.S. Department of Transportation
Federal Highway Administration
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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-17-086 Date: January 2018 |
Publication Number: FHWA-HRT-17-086 Date: January 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 Strategic Highway Safety Plan.(1) 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 stop-controlled intersections that included basic signing and pavement markings. This strategy is intended to reduce the frequency and severity of crashes at stop-controlled intersections by alerting drivers approaching a stop-controlled intersection. The results indicate reductions for all crash types (i.e., total, fatal and injury, rear-end, right-angle, and nighttime crashes). The economic analysis results suggest that the multiple low-cost treatments at stop-controlled intersections, even with conservative assumptions on 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.
Jonathan Porter, Ph.D.
Acting 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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| 1. Report No. FHWA-HRT-17-086 |
2. Government Accession No. | 3. Recipient's Catalog No. | |||
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| 4. Title and Subtitle Safety Evaluation of Multiple Strategies at Stop-Controlled Intersections |
5. Report Date January 2018 |
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| 6. Performing Organization Code | |||||
| 7. Author(s) Thanh Le, Frank Gross, Bhagwant Persaud, Kimberly Eccles, and Jonathan Soika |
8. Performing Organization Report No. | ||||
| 9. Performing Organization Name and Address VHB 8300 Boone Blvd., Ste. 700 Vienna, VA 22182-2626 Persaud and Lyon, Inc 87 Elmcrest Road Toronto, Ontario M9C 3R7 |
10. Work Unit No. | ||||
| 11. Contract or Grant No. DTFH61-13-D-00001 |
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| 12. Sponsoring Agency Name and Address U.S. Department of Transportation Federal Highway Administration 1200 New Jersey Avenue, SE Washington, DC 20590 |
13. Type of Report and Period Covered Safety Evaluation Final Report; October 2010–September 2017 |
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| 14. Sponsoring Agency Code HRDS-20 |
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| 15. Supplementary Notes. 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 Program and Task Manager was Roya Amjadi (HRDS-20). |
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| 16. Abstract The Development of Crash Modification Factors program studied the safety performance of various stop-controlled intersections for the Evaluation of Low-Cost Safety Improvements Pooled Fund Study. This study evaluated the safety effectiveness of multiple low-cost treatments at stop-controlled intersections. Improvements included basic signing and pavement markings. This strategy is intended to reduce the frequency and severity of crashes at stop-controlled intersections by alerting drivers to the presence and type of approaching intersection. Geometric, traffic, and crash data were obtained at three- and four-legged, two- and four-lane major road, and urban and rural stop-controlled intersections in South Carolina. To account for potential selection bias and regression to the mean, an empirical Bayesian before–after analysis was conducted, using reference groups of untreated intersections with similar characteristics to the treated sites. The analysis also controlled for changes in traffic volumes throughout 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 reductions are statistically significant at the 95-percent confidence level for all crash types. For all crash types combined, the crash modification factors (CMFs) are 0.917 for all severities and 0.899 for fatal and injury crashes. The CMFs for rear-end, right-angle, and nighttime crashes are 0.933, 0.941, and 0.853, respectively. The benefit–cost ratio estimated with conservative cost and service life assumptions is 12.4 to 1 for total crashes at unsignalized intersections. The results suggest that the 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 Stop-controlled, unsignalized, intersection, low cost, safety improvements, safety evaluations, empirical Bayesian, before–after, multi-strategy, multiple treatments |
18. Distribution Statement No restrictions. This document is available to the public through the National Technical Information Service, Springfield, VA 22161. http://www.ntis.gov |
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| 19. Security Classif. (of this report) Unclassified |
20. Security Classif. (of this page) Unclassified |
21. No. of Pages: 99 |
22. Price | ||
| Form DOT F 1700.7 (8-72) | Reproduction of completed pages authorized. | ||||
SI* (Modern Metric) Conversion Factors
| AADT | annual average daily traffic |
|---|---|
| B/C | benefit–cost |
| CMF | crash modification factor |
| EB | empirical Bayesian |
| ELCSI-PFS | Evaluation of Low-Cost Safety Improvements Pooled Fund Study |
| FHWA | Federal Highway Administration |
| MUTCD | Manual on Uniform Traffic Control Devices |
| NCHRP | National Cooperative Highway Research Program |
| PDO | property damage only |
| PE | preliminary engineering |
| RTM | regression to the mean |
| SCDOT | South Carolina Department of Transportation |
| SPF | safety performance function |
| USDOT | U.S. Department of Transportation |
