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

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Publication Number: FHWA-RD-03-050

Surrogate Safety Measures From Traffic Simulation Models

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1. Introduction

Safety is an area of increased attention and awareness within transportation engineering. Historically, safety has been difficult to assess for new and innovative traffic treatments, primarily because of the lack of good predictive models of crash potential and lack of consensus on what constitutes a safe or unsafe facility. This Federal Highway Administration (FHWA) project is intended to investigate the potential for deriving surrogate measures of safety from existing microscopic traffic simulation models for intersections. The process of computing the measures in the simulation, extracting the required data, and summarizing the results is denoted as the Surrogate Safety Assessment Methodology (SSAM). These surrogate measures could then be used to support traffic engineering alternatives evaluation with respect to safety for both signalized and unsignalized intersections.

This document has several main sections:

  1. Review of previous work in modeling of safety at traffic facilities (focusing on intersection safety modeling) using surrogate measures (covered in chapter 2).
  2. Survey of the capabilities of existing traffic simulation models to support derivation of surrogate measures of safety (covered in chapters 3, 4, and 5).
  3. Identification of use cases and functional requirements for a surrogate safety assessment tool that interacts with traffic simulation model outputs (covered in chapter 6).
  4. Specification of algorithms for calculating surrogate measures of safety appropriate for intersections (covered in chapters 7 and 8).
  5. Suggestions for validation activities to support the analysis potential for surrogate measures and compare surrogate measures from simulation models with field data and previous safety studies (covered in chapter 9).
  6. Report summary (covered in chapter 10).
  7. References (chapter 11).

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