U.S. Department of Transportation
Federal Highway Administration
1200 New Jersey Avenue, SE
Washington, DC 20590

Skip to content U.S. Department of Transportation/Federal Highway AdministrationU.S. Department of Transportation/Federal Highway Administration

Federal Highway Administration Research and Technology
Coordinating, Developing, and Delivering Highway Transportation Innovations

This report is an archived publication and may contain dated technical, contact, and link information
Publication Number: FHWA-HRT-08-051
Date: June 2008

Surrogate Safety Assessment Model and Validation: Final Report

PDF Version (3.39 MB)

PDF files can be viewed with the Acrobat® Reader®


  • [1] On closer examination, both crash counts and traffic counts actually exhibit somewhat higher variance than the mean, which further strengthens the point being made.

  • [2] Although this project focuses on simulated vehicle trajectory data, it would seem entirely applicable to the analysis of real-world vehicle trajectory data as well.

  • [3] The SSAM acronym may be used in the sense “the software,” as in SSAM identifies conflicts.

  • [4] Inquiries for the SSAM software and documentation should be directed to the FHWA Office of Safety R&D.

  • [5] Not used in the study because no data were collected in the simulation on single-vehicle events.

  • [6] Spearman’s rank correlation coefficient is equivalent to a Pearson correlation of ranks; however, the Spearman equation is relatively simple to compute. In the case that there are ties among the rankings, a slightly more complicated procedure is used.

  • [7] NEMA is an acronym for National Electrical Manufacturers Association, an organization that has established a standard specification for traffic signal operations. This standard is commonly used in traffic controllers in North America.

  • [8] It was noted in the Field Validation chapter that simulated volumes were differed somewhat from the ADT volumes used for traditional crash prediction.

  • [9] Please direct also inquiries regarding SSAM to the FHWA Office of Safety R&D.

United States Department of Transportation - Federal Highway Administration