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U.S. Department of Transportation U.S. Department of Transportation Icon United States Department of Transportation United States Department of Transportation
FHWA Highway Safety Programs

Highway Safety Manual: Overview Brochure

brochure.pdf (933.73 KB)

Why a Highway Safety Manual?

Prior to this first edition of the HSM, there were no widely accepted tools for engineers to use to quantify the potential for reductions 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. An effective resource was urgently needed to quantify and predict the expected crash frequency of elements considered in road planning, design, construction, operation, and maintenance.

The HSM begins to fill this gap, providing transportation professionals with knowledge, techniques, and methodologies to quantify the safety-related effects of transportation decisions – similar to the way operational impacts are quantified in the Highway Capacity Manual and environmental impacts are calculated through the NEPA process. The HSM provides the best factual information and tools in a useful form to facilitate roadway decisions based on the explicit consideration of their effects on potential future crash frequency and severity.

Benefits include an improved decision-making process for applying safety treatments, resulting in potential cost savings to highway agencies. Time spent justifying a safety decision can be reduced by conducting a definitive, science-based analysis; and safety elements can be integrated in the most cost-effective manner in the project development process. In the end, the HSM provides tools to support improved traffic safety management and a reduction in the frequency and severity of traffic crashes.

What types of benefits are expected with its use?

  • Safety improvements
    • Improve the decision-making process and effectiveness of countermeasures to reduce the number and severity of crashes.
  • Cost savings
    • Decisions can be made based on quantitative evaluations that predict crash reduction associated with improvements, instilling confidence that safety funds are being applied most effectively.
    • Time spent justifying a safety decision will be reduced by conducting a definitive, science-based analysis.
    • Integrate safety elements in the most cost-effective manner in the project development process.

System Planning

Identify needs and program projects

HSM Application - Part B

  • Identify sites most likely to benefit from safety improvement
  • Identify targeted crash patterns for the network
  • Prioritize expenditures for efficiency

Project Planning & Preliminary Engineering

Identify alternatives and choose the preferred solution

HSM Application - Part B

  • Identify targeted crash patterns for the project
  • Evaluate countermeasures’ costs and effectiveness
  • Compare change in crash frequency to predict safety effect of alternatives

Design and Construction

Develop design plans and build projects

HSM Application - Part C

  • Evaluate how performance measures are impacted by design changes and construction
  • Assess potential change in crash frequency during design exception evaluation

Operations and Maintenance

Modify existing conditions to maintain and improve safe and efficient operation

HSM Application - Part B and C

  • Identify crash patterns at existing locations
  • Evaluate safety effectiveness of potential countermeasures
  • Modify policies and design criteria for future planning and design

What are the contents?

Part A - Introduction, Human Factors, and Fundamentals
Chapter 1 – Introduction and Overview
Chapter 2 – Human Factors
Chapter 3 - Fundamentals

Part B - Roadway Safety Management Process
Chapter 4 – Network Screening
Chapter 5 – Diagnosis
Chapter 6 – Select Countermeasures
Chapter 7 – Economic Appraisal
Chapter 8 – Prioritize Projects
Chapter 9 – Safety Effectiveness Evaluation

Part C - Predictive Method
Chapter 10 – Rural Two-Lane Roads
Chapter 11 – Rural Multilane Highways
Chapter 12 – Urban and Suburban Arterials
Chapter 18 & Chapter 19 – Freeways

Part D - Crash Modifi cation Factors
Chapter 13 – Roadway Segments
Chapter 14 – Intersections
Chapter 15 – Interchanges
Chapter 16 – Special Facilities
Chapter 17 – Road Networks

Where can I find more information?

For more information, visit the Highway Safety Manual website at