Skip Ribbon Commands
Skip to main content
Home|Legal Information|Privacy Policy|Copyright Notice
Background/Audience Benefits


The ultimate goal for the HSM is providing quantitative methods to develop a safer, more efficient roadway transportation system. The Manual achieves this goal by providing information and tools in a useful format so practitioners, managers, and executives can make the best decisions to reduce the number and severity of crashes on our nation’s roadways. The HSM provides transportation professionals with knowledge, techniques, and methodologies to quantify the safety-related effects of transportation decisions. By using the HSM, practitioners can quantify crash frequency and severity and integrate that information into roadway planning, design, operations, and maintenance decisions.

The concept of developing a safety manual began at a conference session at the 1999 TRB Annual Meeting, it was determined there was an absence of and a need for a single authoritative document to use for estimating safety impacts. Prior to this first edition of the HSM, there were no widely accepted tools for engineers to use to quantify the potential change in crash frequency and severity when making transportation facility design and operations decisions. As a result, safety considerations often carried little weight in the project development process, limiting the ability of transportation professionals to discuss and act upon safety-related recommendations during project development.

The formation of a joint TRB Task Force jump-started the development of the HSM with support from the American Association of State Highway Transportation Officials (AASHTO), Federal Highway Administration (FHWA), and Institute of Transportation Engineers (ITE).

Today along with AASHTO, the Federal Highway Administration (FHWA) and the Transportation Research Board (TRB), through the Highway Safety Performance Committee (ANB25), coordinate implementation of the HSM and any additional research activities. The Highway Safety Performance Committee fosters the development, validation, and increased knowledge of science-based methods, procedures, and measures that will increase the safety of the nation’s highways.


Target Audiences

The target audience for the HSM is primarily managers, executives, and practitioners from five key groups:

  • Management – Professionals and managers from transportation administration and other decision-makers;
  • Planners – Those involved in developing long- and short-term transportation plans, corridor studies, environmental assessments, and alternative assessments;
  • Designers – Individuals who do project scoping, preliminary, and final design, including alternative comparisons;
  • Operations & Maintenance – Individuals who conduct operational analysis and determine the condition of the roadway pavement, guardrail, signing, etc.; and
  • Safety Analysts – Individuals responsible for collecting and analyzing roadway safety data, system safety performance reviews, crash investigations, safety assessments and audits, and/or countermeasure selection.

The HSM, which does not require sophisticated data warehouses to make an impact, is written for practitioners at the state, county, metropolitan planning organization (MPO), or local level. The tools in the HSM are scalable so they can be implemented by DOTs with robust data warehouses and processing capability or by local authorities with little more than a laptop.



The HSM is the key ingredient that will allow for quantitative safety performance evaluation. This will:

  • Improve the decision-making process for applying safety treatments;
  • Demonstrate the impact on safety of various design alternatives;
  • Address specific needs;
  • Integrate safety elements in the most cost-effective manner;
  • Predict the change in crash frequency or severity associated with a particular improvement; and
  • Allows agencies to do more with less by focusing resources on locations with the highest potential for safety improvement.

By using the HSM, practitioners can:

  • Identify sites with potential for crash frequency or severity reduction;
  • Identify factors contributing to crashes and associated potential countermeasures to address these issues;
  • Evaluate the change in crash frequency of implemented treatments;
  • Conduct economic appraisals of improvements to prioritize projects;
  • Calculate the effect of various design alternatives on crash frequency and severity; and
  • Estimate potential crash frequency and severity on highway networks, and the potential effects of transportation decisions on crashes.