Overview of HSM chapters

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

Part D - Crash Modifi cation Factors

Chapter 13 – Roadway Segments

Chapter 14 – Intersections

Chapter 15 – Interchanges

Chapter 16 – Special Facilities

Chapter 17 – Road Networks

An Overview of the

HIGHWAY SAFETY MANUAL

What is its purpose?

The purpose of the Highway Safety Manual (HSM) is to provide the best factual information 

and proven analysis tools for crash frequency prediction. The HSM will facilitate integrating 

quantitative crash frequency and severity performance measures into roadway planning, 

design, operations, and maintenance decisions. The primary focus of the HSM is the 

increased application of analytical tools for assessing the safety impacts of transportation 

project and program decisions.

What are its uses?

• Identify sites with the most potential for crash frequency or severity reduction.

• Identify factors contributing to crashes and associated potential countermeasures to 

address these issues.

• Evaluate the crash reduction benefi ts of implemented treatments.

• Conduct economic appraisals of improvements to prioritize projects.

• Calculate the effect of various design alternatives on crash frequency and severity.

• Estimate potential crash frequency and severity on highway networks, and the potential 

effects of transportation decisions on crashes.

How does the HSM apply to the Project Development Process?

System Planning

Planners 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

Safety Engineers and Project Managers 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

Operations and Maintenance

Traffic and Operations Engineers modify existing conditions 

to maintain and improve safety 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

Design and Construction

Project Managers, Designers, and Construction 

Engineers 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
Is software support available?

Yes. HSM methodologies will be supported by 

the following software programs:

• SafetyAnalyst is a suite of analytical 

tools for guiding the decision-making 

process to identify safety improvement 

needs and develop a system-wide program 

of site-specifi c improvement projects. 

SafetyAnalyst supports Part B of the HSM. 

www.safetyanalyst.org

• The Interactive Highway Safety Design 

Model (IHSDM) is a suite of software 

analysis tools for evaluating safety and 

operational effects of geometric design 

decisions. It performs the predictive method 

for the facilities in Part C of the HSM. 

www.tfhrc.gov/safety/ihsdm/ihsdm.htm

• The Crash Modifi cation Factors 

Clearinghouse houses a web-based 

database of CMFs along with supporting 

documentation to help transportation 

engineers identify the most appropriate 

countermeasure for their safety needs. 

The CMF Clearinghouse supports 

Part D of the HSM.

www.cmfclearinghouse.org

An Overview of the

HIGHWAY SAFETY MANUAL

What about tort liability and risk management?

The HSM is designed to support practitioners in managing risk. The quantitative analysis 

of safety data provides protection to public agencies concerned about risk. The HSM 

is neither intended to be, nor does it establish, a legal standard of care for users or 

professionals. No standard of conduct or any duty toward the public or any person shall 

be created or imposed by the publication and use or nonuse of the HSM. Documentation 

used, developed, compiled or collected for analyses conducted in connection with the 

HSM may be protected under Federal law (23 USC 409).

What training is available to assist me in using the HSM?

Step by step procedures with examples are included in the HSM to assist practitioners. 

Additionally, training courses are available through the National Highway Institute at 

http://nhi.fhwa.dot.gov.

• New Approaches to Highway Safety Analysis (NHI-380075)

• HSM Practitioners Guide to Two-Lane Rural Roads (NHI-380070A)

• HSM Practitioners Guide to Multilane Urban/Suburban Highways (NHI-380070B)

• HSM Application to Intersections (NHI-380105*)

• HSM Workshop (NHI-380106*)

• Application of Crash Reduction Factors (NHI-380093)

• Science of Crash Reduction Factors (NHI-380094)

• Interactive Highway Safety Design Model (IHSDM) (NHI-380071, NHI-380100* 

web-based)

*Course under development

How much does it cost? Can I buy it online? 

The HSM is currently available for purchase from AASHTO for $325 for AASHTO 

members and $390 for non-members. Discounts are available for those states taking 

HSM training. Both hard copy and electronic versions are available. To purchase, visit 

http://bookstore.transportation.org and search under code HSM-1. 

What data are needed? 

Three types of data are needed to apply the HSM safety prediction methodologies: site 

characteristics data, traffi c volume data, and crash data. Details are available in the 

Highway Safety Manual Data Needs Guide, available here: www.trb.org/Publications/

Blurbs/Highway_Safety_Manual_Data_Needs_Guide_159984.aspx

Where can I fi nd more information?

The most up-to-date information on the HSM can be found here: 

www.highwaysafetymanual.org

HOT TOPICS OF THE HSM