The National Academies

NCHRP 17-35 [Completed]

Evaluation of Safety Strategies at Signalized Intersections

  Project Data
Funds: $750,000
Research Agency: University of North Carolina at Chapel Hill
Principal Investigator: Raghavan Srinivasan
Effective Date: 11/1/2006
Completion Date: 5/31/2011


In 1998, AASHTO approved its Strategic Highway Safety Plan, which was developed by the AASHTO Standing Committee on Highway Traffic Safety with the assistance of the Federal Highway Administration, the National Highway Traffic Safety Administration, and the Transportation Research Board Committee on Transportation Safety Management. The plan includes strategies in 22 key emphasis areas that affect highway safety. Each of the emphasis areas includes strategies and an outline of what is needed to implement each strategy. NCHRP Project 17-18(3) developed a series of guides, which were collectively published as NCHRP Report 500, A Guide for Reducing Collisions Involving Pedestrians, to assist state and local agencies in reducing injuries and fatalities in targeted emphasis areas. The guides correspond to the emphasis areas outlined in the AASHTO Strategic Highway Safety Plan. Each guide includes a brief introduction, a general description of the problem, strategies to address the problem, and a model implementation process. Seventeen guides have been published to date.

The safety effectiveness of many of the strategies in the guides has not yet been rigorously evaluated. The Federal Highway Administration, in partnership with the state DOTs, has initiated a project to evaluate the safety effectiveness of the strategies in Volumes 1 through 6 of NCHRP Report 500. This project will encompass safety effectiveness evaluations of strategies from NCHRP Report 500, Volume 12: Guidance for Implementation of the AASHTO Strategic Highway Safety Plan, A Guide for Reducing Collisions at Signalized Intersections. In this project, data will be collected and before-after safety effectiveness evaluations will be performed at sites where selected safety strategies have been implemented. The results of this evaluation will assist practitioners in selecting the appropriate strategy for a particular location.


The objective of this project is to develop reliable accident modification factors for the strategies identified in NCHRP Report 500, Volume 12, Guidance for Implementation of the AASHTO Strategic Highway Safety Plan, A Guide for Reducing Collisions at Signalized Intersections.

Accomplishment of the project objective will require at least the following tasks.

TASKS (1.) Conduct a literature review of ongoing and recently completed studies that can contribute to the evaluation of the strategies in NCHRP Report 500, Volume 12. This literature review may include, but is not limited to, studies of the safety impacts of the strategies and publications that address the use of those strategies. (2.) Conduct a survey of state and local agencies to identify (a) approximate number of locations where the strategies are currently in service; (b) published and unpublished studies pertaining to the strategies; (c) availability of suitable databases (e.g., crash, roadway inventory); (d) before-and-after-installation information that may be used to evaluate the strategies; and (e) other innovative strategies used by the jurisdiction but not in the Guide. (3.) Submit an interim report summarizing the findings of Tasks 1 and 2 including an updated, detailed work plan for the rigorous evaluation of the strategies for which accident modification factors (AMFs) will be developed. The work plan should specify the evaluation methods that will be employed, the additional data that will need to be collected in Task 5, and the site characteristics that will be used in the evaluation of strategies (e.g., volume and facility type). (4.) Meet with the NCHRP panel to review the Task 3 interim report approximately 1 month after its submittal. Submit a revised interim report addressing the panel's review comments. (5.) Collect detailed data and conduct the evaluation of the selected strategies. This data, as a minimum, includes: number of installations, installation date and location, crash data, geometric characteristics, traffic operations and volume data, and other explanatory information. (6.) Submit a final report documenting the entire research effort. The final report shall describe how the project was conducted and present the determined effectiveness, AMFs, of the strategies. The report will also include appendices documenting the implementation/installation data available from all jurisdictions contacted.

Status: The project has been completed and the final report has been published as NCHRP Report 705.

Product Availability: NCHRP Report 705, "Evaluation of Safety Strategies at Signalized Intersections."

The appendices are available at http://onlinepubs.trb.org/onlinepubs/nchrp/docs/NCHRP17-35_Appendices.pdf

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