Assessing the Reliability of Hard Braking and Other Vehicle-Based Metrics as Surrogate Safety Measures

Transportation safety is a critical concern for agencies nationwide, and recent technological advances have enabled the collection of vast amounts of vehicle trajectory and behavioral data. Among these data, hard-braking events have emerged as a surrogate safety measure, which can be used to infer the possibility of near misses and crashes. Agencies and data providers increasingly rely on metrics such as hard braking, excessive acceleration, and high-speed cornering, derived from connected vehicle (CV) data, to identify risky driving behavior and to proactively address safety risks. Unlike traditional crash data, which are retrospective and often delayed, surrogate safety measures offer real-time insights into roadway conditions and driver behavior. This immediacy allows for earlier identification of emerging safety concerns and the implementation of timely countermeasures. However, the reliability and validity of these surrogate measures are not universally established. Their effectiveness can vary depending on factors such as sight distance, geometric design, speed limits, traffic control devices, work zone configurations, and queue warning locations. For instance, a hard-braking event at a congested urban intersection may indicate different risks than one on a rural freeway. The objective of this research is to rigorously evaluate the reliability and validity of hard braking and other vehicle-based metrics, such as excessive acceleration and high-speed cornering, as surrogate safety measures across diverse transportation environments.

• Record URL:
  • http://apps.trb.org/cmsfeed/TRBNetProjectDisplay.asp?ProjectID=6054
• Supplemental Notes:
  • Contract to a Performing Organization has not yet been awarded.

Language

• English

Project

• Status: Proposed
• Funding: $600,000.00
• Contract Numbers:

  Project 17-149

• Sponsor Organizations:

  National Cooperative Highway Research Program

  Transportation Research Board
  500 Fifth Street, NW
  Washington, DC  United States  20001

  American Association of State Highway and Transportation Officials (AASHTO)

  444 North Capitol Street, NW
  Washington, DC  United States  20001

  Federal Highway Administration

  1200 New Jersey Avenue, SE
  Washington, DC  United States  20590
• Project Managers:

  Zhao, Yi

• Start Date: 20260608
• Expected Completion Date: 0
• Actual Completion Date: 0

Subject/Index Terms

• TRT Terms: Braking; Highway safety; Mechanical acceleration; Quantitative metrics; Reliability; Steering; Validity
• Subject Areas: Highways; Planning and Forecasting; Safety and Human Factors;

Filing Info

• Accession Number: 01992141
• Record Type: Research project
• Source Agency: Transportation Research Board
• Contract Numbers: Project 17-149
• Files: TRB, RIP
• Created Date: Jun 9 2026 1:01PM