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Publication Number: FHWA-HRT-08-051
Date: June 2008

Surrogate Safety Assessment Model and Validation: Final Report

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  • [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