Implementation Guide for Managers

September 2011

FHWA-SA-11-48
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Technical Report Documentation Page

1. Report No.

FHWA-SA-11-48

2. Government Accession No. 3. Recipient’s Catalog No.

4. Title and Subtitle

HSM Implementation Guide for Managers

5. Report Date

September 2011

6. Performing Organization Code

7. Author(s)

Tim Neuman (CH2M HILL) and Ida van Schalkwyk (CH2M 

HILL).

8. Performing Organization Report No.

9. Performing Organization Name and Address

Cambridge Systematics, Inc.

100 CambridgePark Drive, Suite 400

10. Work Unit No.

Cambridge, MA 02140

11. Contract or Grant No.

DTFH61-05-D-00026-T-10-001

12. Sponsoring Agency Name and Address

Department of Transportation

Federal Highway Administration

1200 New Jersey Ave., SE

Washington, DC 20590

13. Type of Report and Period Covered

14. Sponsoring Agency Code

15. Supplementary Notes

FHWA: Esther Strawder, Office of Safety (COTM)

16. Abstract

This guide is intended for managers of departments of transportation (DOT) charged with leading and 

managing agency programs impacting the project development process and safety programs. This 

guide is based on lessons learned from early adopters of the Highway Safety Manual (HSM), many of 

whom are participating in the AASHTO’s Lead State Initiative. It outlines what the HSM is (and is not), 

how it relates to other core technical documents and policies, and the potential benefits of its use. These 

benefits can be broadly understood as a means to improve the safety performance of their highway 

system. In this context the improvement of safety is defined as a reduction in fatalities and injuries. The 

guide is written in three sections – Introduction to the HSM, HSM Implementation Considerations, and 

HSM Implementation Opportunities in Program Development and Project Delivery.

17. Key Words

safety, Highway Safety Manual, HSM, HSM 

implementation

18. Distribution Statement

19. Security Classif. (of this report)

Unclassified

20. Security Classif. (of this page)

Unclassified

21. No of Pages

34

22. Price

Form DOT F 1700.7 (8-72) Reproduction of completed pages authorized
iii

Table of Contents

Executive Summary ............................................................................................................... 1

1. Introduction to the Highway Safety Manual.................................................................... 2

Purpose of the Implementation Guide.........................................................................................2

Benefits of New Concepts of Safety.............................................................................................3

2. HSM Implementation Considerations.............................................................................. 5

Implementation Guiding Principles .............................................................................................5

Drivers and Challenges to Successful Implementation of the HSM................................................6

Management Strategies..............................................................................................................7

Agency Champion(s) ...................................................................................................................7

Develop an Implementation Plan ................................................................................................8

Examine and Revise Agency Policies............................................................................................9

Address Risk Management and Legal Issues...............................................................................10

Data and Data Systems.............................................................................................................11

Information Technology............................................................................................................12

Development of Tools for HSM Implementation........................................................................12

Budgets for Implementation .....................................................................................................13

Initiate HSM Training ................................................................................................................13

Develop Sustainable Technical Expertise ...................................................................................14

Technology Transfer to External Partners..................................................................................15

Organizational Needs and Issues...............................................................................................16

3. HSM Implementation Opportunities in Program Development and Project Delivery ...... 17

Program Development..............................................................................................................17

Project Development................................................................................................................19

Project Scoping and Design Criteria .......................................................................................................19

Scoping Using the Two Dimensions of Safety ........................................................................................20

Purpose and Need..................................................................................................................................20

Project Planning, Alignment, and Alternative Studies ................................................................21

Design and Context Sensitive Solutions.................................................................................................23

Preliminary and Final Engineering..........................................................................................................23

Operations and Maintenance....................................................................................................24
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4. Summary...................................................................................................................... 25

5. References.................................................................................................................... 26

6. Resources..................................................................................................................... 27

On-Line ....................................................................................................................................27

Publications..............................................................................................................................27

7. List of Acronyms ........................................................................................................... 28

List of Exhibits

Exhibit 1: Nominal and Substantive Safety Concepts ..........................................................................4

Exhibit 2: Examples of Driving Forces and Restraining Forces to Apply Quantitative Safety 

Information to Transportation Engineering .........................................................................7

Exhibit 3: Lead States and Support States in the NCHRP 17-50 HSM Lead State Initiative Project .........9

Exhibit 4: The Project Development Process and Opportunities to Implement the HSM.....................18
1

Executive Summary

The AASHTO Highway Safety Manual (HSM), published in 2010, presents for the first time a 

complete collection of technical knowledge describing the quantitative safety effects – motor 

vehicle crashes and their outcomes – of actions involving the highway and street environment. 

The HSM was developed through a 10-year research effort. It was written for use by any 

transportation professional concerned with highway and traffic safety. The HSM is organized 

in four parts:

• Part A – Introduction, Human Factors, and Fundamentals of Safety;

• Part B – Roadway Safety Management Process;

• Part C – Predictive Methods; and

• Part D – Crash Modification Factors.

The HSM is a potentially transformative document for Departments of Transportation (DOT) 

and other agencies responsible for the planning, design, construction, and operation of their 

highway systems. Under current practices agency actions are based on results from proven, 

science-based tools to measure or estimate effects of traffic operations, of a myriad 

environmental factors, and of the many aspects of capital and life-cycle costs. However, no 

proven and accepted tools or methods for understanding explicit safety effects existed in the 

past in a central document. With publication of the HSM, DOTs and other agencies now for the 

first time have access to a proven and science-based means of characterizing the explicit safety 

effects (i.e., crash frequency and severity) of decisions and actions of an agency.

The mission and vision statements of most DOTs refer directly to safety as a core value. The 

HSM adds a new dimension to defining and understanding what the term “safety” really 

means. To fully understand and take advantage of the HSM, DOTs will need to conduct 

thorough reviews of their organization and management, data systems, program and project 

development policies and methods, internal training programs, and even culture. Investments 

in training and technology transfer, and in improved or different data and skills will be needed. 

An assessment of budgets may be needed.

This guide is intended for managers of DOTs charged with leading and managing agency 

programs impacting the project development process and safety programs. This guide is based 

on lessons learned from early adopters of the HSM, many of whom are participating in 

AASHTO’s Lead State Initiative. It outlines what the HSM is (and is not), how it relates to other 

core technical documents and policies, and the potential benefits of its use. These benefits can 

be broadly understood as a means to improve the safety performance of their highway system. 

In this context the improvement of safety is defined as a reduction in fatalities and injuries. The 

guide is written in three sections – Introduction to the HSM, HSM Implementation 

Considerations, and HSM Implementation Opportunities in Program Development and Project 

Delivery.
2

1. Introduction to the Highway Safety Manual

The AASHTO Highway Safety Manual (HSM), published in 2010, represents the culmination of 

10 years of research and development by an international team of safety experts, academics, and 

practitioners. The HSM was envisioned as a companion document to and modeled after the 

well-known Highway Capacity Manual. Under leadership from both the American Association of 

State Highway Officials (AASHTO) through the National Cooperative Highway Research 

Program (NCHRP) and the Federal Highway Administration (FHWA), and with direction from 

a Task Force of the Transportation Research Board (TRB), a major research program provided 

the technical contents of the HSM and also funded its development into a practitioner-friendly 

document.

The HSM represents the greatest potential for influencing the actions and outcomes of state 

DOTs in the past 50 years. The HSM captures the knowledge base associated with the proven 

relationship between crashes and their outcomes and actions or implemented decisions. The 

HSM is intended for use by any and all professionals charged with planning, design, 

construction, operations, and maintenance of a road or highway system. The HSM was 

developed through funding from AASHTO and the FHWA. The research basis for HSM 

contents has its foundation in National Academies administered peer-reviewed research. As 

such, users of the document can apply the values and methods with confidence, knowing they 

represent the best science available at the time of its publication.

Purpose of the Implementation Guide

This document is intended as a reference for managers of state DOTs and local highway 

agencies that are interested in or responsible for initiating the implementation of the AASHTO 

HSM within their organization. It provides guidance on processes, resources, approaches, and 

lessons learned from early adopters of the HSM.

The guide offers background on what the HSM is and what its benefits to users will be. It 

presents considerations to managers assigned the task of participating in or leading an HSM 

implementation effort. These considerations come from discussion with DOT peers who have 

already begun implementation and have learned valuable lessons.

Management strategies are suggested, including the need for a champion, key executive 

leadership support, and development of a specially tailored implementation plan, which would 

include training, organizational issues, revisions to agency policies and procedures, risk 

management, data availability, analytical tools, and information technology.
3

The second major section of the guide covers how the HSM, once implemented and 

institutionalized, can affect program and project delivery for all projects – not just those 

concerned with safety improvements.

For further assistance or background on the HSM, users of this Guide are encouraged to visit 

http://www.highwaysafetymanual.org.

Benefits of New Concepts of Safety

Safety is a core value of most if not all state DOTs. Safety plays a prominent role in the mission 

or vision statements of most. Customers, highway system users, and taxpayers have been 

assured and told that maintaining or improving safety is a top priority, and that much of an 

agency’s investments are intended to produce a “safe” highway or system.

“Safety” has traditionally been incorporated in highway programs and projects within a 

“standards-based” framework. Design standards, design policies, and warrants such as the 

AASHTO Policy on Geometric Design, AASHTO Roadside Design Guide, and Manual on 

Uniform Traffic Control Devices, and individual state DOT design manuals are the core basis 

for decision-making and project development. Many agencies have sophisticated asset 

management systems that facilitate system monitoring and program development of hard 

assets such as bridges and pavement, but lack comparable systems for safety.

Standards, manuals, warrants, etc., serve many purposes. Among them are quality control, 

efficiency in design, and consistency in approach that translates to better understanding of 

contractors and better bids. Many design standards have some element of safety assumed or 

implied by their derivation of design values, but in many cases there are other considerations 

besides safety in how and why a design standard or design values were established. Indeed, a 

deep understanding of the background behind much of industry practice shows that such 

presumptive relationships in fact often do not exist. Ezra Hauer, a noted researcher in highway 

safety, referred in 1999 to the use of standards in the context of delivering safety as nominal 

safety.

What is different about the HSM, and where it offers potentially significant benefits to agencies, 

is in the introduction of a second dimension of safety, which Hauer described as substantive 

safety. Exhibit 1 demonstrates the difference between nominal and substantive safety. 

Substantive safety is quite simply the performance of a facility as measured by crashes and their 

outcomes, fatalities and injury. In the context of DOT programs and actions, the known 

substantive safety, when compared to a statistically reliable and relevant threshold, provides a 

basis for decision-making around project selection, scope, and basic approach. For 

contemplated actions or alternatives, the predicted or expected substantive safety of each 

alternative can be assessed and thus contribute to the selection of a preferred approach.
4

EXHIBIT 1

Nominal and Substantive Safety Concepts

By providing a way of estimating or understanding the substantive safety implications of 

design decisions or actions, DOTs can now:

• Better inform their decision-making process and thereby improve the effectiveness of 

countermeasures to reduce the number and/or severity of crashes;

• Improve the confidence that safety funds are being applied most effectively;

• Reduce time and improve the justification of safety improvement programs and projects;

• Provide meaningful quantitative safety measures to inform project decisions and thus 

improve understanding of tradeoffs involving other values such as environmental concerns, 

right-of-way, and stakeholder issues;

• More directly integrate safety in the overall DOT program and project development process; 

and

• Demonstrate and prove over time, the direct and meaningful return for investments in 

safety to their sponsors and stakeholders.

In effect, the full implementation and use of the HSM will help a DOT accomplish what its 

customers and stakeholders expect, which is providing the highest level of safety performance 

for the financial and other resources provided to the DOT. Managers should understand and 

communicate to staff that the full acceptance and implementation of the approaches, methods, 

and values in the HSM and companion resources offers substantial systematic benefits for 

enhancing safety.
5

2. HSM Implementation Considerations

Any new organizational initiative requires careful thought and planning. DOT managers can 

expect that introduction of new requirements, technical or process, will be met with some 

skepticism and fear. Indeed, for staff successfully doing their jobs for many years, delivering a 

message that they need to do something new may require extra effort and sensitivity to 

demonstrate the value and necessity of the new initiative.

There will be many within an agency that will understand and embrace the new approach. 

Such early, enthusiastic adopters should be sought and nurtured. Implementation planning for 

the HSM should reflect the specific attributes, culture and organizational structure, and 

capabilities of the organization. The culture of DOTs with respect to participation in industry 

research and application of new ideas and technology varies widely. Managers should 

understand their unique culture and plan accordingly. Managers should approach 

implementation with an understanding of how their agency is organized, who are the 

important influencers and decision-makers, who can and should be allies and supporters of the 

effort, and what is reasonably achievable over time given the agency’s other priorities.

Implementation Guiding Principles

Lessons learned from early adopters of the HSM, including AASHTO lead states, produce the 

following guiding principles that managers should incorporate in their implementation efforts.

• Employ a Consistent Technical Approach – Predictive methods, assumptions, use of common 

databases, common crash modification factors, and common benefit/cost approaches are all 

important for both internal purposes and external credibility.

• Encourage Gradual Changes – Agencies will have varying levels of quality and quantity of 

necessary data and IT systems. Changes in policies, use of the HSM and training of staff 

should not “outpace” the ability or progress of the data and decision-support systems. Seek 

to establish and then maintain momentum in implementation.

• Anticipate and Champion Culture Change – Many HSM concepts are new and may run counter 

to staff understanding of safety. Training of staff, particularly highway designers, should 

carefully explain HSM concepts in their proper context stressing that the HSM does not 

replace design manuals and standards, but merely supplements them.

• Manage Training – Not everyone needs to be an expert in the HSM, but most will benefit 

from basic knowledge and all should understand the concept of substantive safety. 

Managers should consider how the HSM will be used, who within the organization (by 

position, by location) should have a deep understanding, and how their internal experts will 

be used. Managers should also consider how others may benefit from the knowledge base 

without having to undergo extensive training.
6

Drivers and Challenges to Successful Implementation of the HSM

Managers will find that implementing the HSM will present challenges similar to the 

implementation of other significant advancements or innovations in the field of transportation,

such as Context Sensitive Solutions and Complete Streets initiatives. Successful implementation 

involves identifying and taking advantage of “drivers” and overcoming “barriers” or 

challenges.

Successfully implemented innovations invariably have drivers, that is, forces that tend to 

promote the innovation. External drivers include customer expectations about the work of the 

agency to deliver safe roads, and the need to justify or account for value from investments in 

projects. For the foreseeable future, it seems clear that funding demands and competing 

priorities will greatly outstrip available resources. In such an environment, it may be easy to 

dismiss the implementation of any new initiative. In the case of the HSM, managers can turn 

the argument around. The DOT’s customers assume that their actions and decisions are 

intended to produce a performance outcome. When investments are made through the 

application of science-based safety concepts in the HSM, agency leaders can feel confident in 

sharing with the public the expected reduction in fatalities and injuries that result from these 

investments.

Significant internal drivers include the individual professionals in the agency, their natural 

desire to be seen as applying the latest and best practices, and their related pride in the 

organization they work for and its place among its peers. Regardless of position within the 

agency, the vast majority of professionals want to do the best job they can and want to learn and 

apply the latest innovations and knowledge in their field. Managers should seek opportunities 

to identify and take advantage of these drivers within their organizations.

There are also typically challenges or restraining forces to any change, which tend to reflect the 

natural human tendency to resist something new. Exhibit 2 summarizes what early adopting 

managers have faced when attempting to introduce the HSM and concepts of quantitative 

safety. Note that these restraining forces tend to reflect internal factors or constraints within the 

agency. All such challenges can be addressed within training and during implementation.
7

EXHIBIT 2

Examples of Driving Forces and Restraining Forces to Apply Quantitative Safety Information to Transportation Engineering

Management Strategies

DOTs that are rapidly implementing the HSM have executed similar strategic approaches. Each 

of these approaches has involved:

• A well-respected leader serving as a champion;

• Development and execution of an implementation plan;

• Examination and revision or development of agency policies and resources;

• Examination of risk management and legal issues;

• Examination of data, information technology, and analytical tools;

• Assessment of budgets and phased approaches to implementation;

• Identification of technical expertise needs and sustainability of technical expertise; and

• Identification of organizational needs and issues.

All of the above are essential elements of successful HSM implementation. The amount of effort 

and resources to adopt each will vary from state to state. The remainder of this document will 

discuss each of these items in further detail.

Agency Champion(s)

There must be at least one strong, visible, and well-respected manager or executive who has a 

stated interest in promoting safety and who can appeal to the sense of professionalism within 

the staff. The finding and designation of a champion – someone who will accept the challenge, 

own the task of HSM implementation, and commit to driving it within the agency is an essential 

element. A champion can insure statewide, consistent, and directed effort towards the 

advancement of safety across various programs and processes. Lack of a champion results in 

no one owning the implementation task, with diversion to other priorities inevitable.
8

The champion should recruit other like-minded staff, if possible from different offices and with 

different functions or jobs. An ideal team includes someone from key headquarters functions 

such as the design and/or traffic engineering offices, the state safety engineer, IT experts, or 

owners of data systems, and mid-level project managers and department managers from field 

or District offices. Each individual can offer insights on the specific barriers to be overcome, 

technical or resource needs, potential early successes, and how to best incorporate changes in 

department policies or approaches.

There should also be an executive sponsor who is high enough up in the organization that he or 

she can make clear the importance of the HSM and how safety will be dealt with going forward. 

The executive sponsor should act in a way that demonstrates the agency’s commitment, 

through providing the right resources, advertising the visibility of the team and its mission, and 

rewarding interim milestones met and early successes.

Develop an Implementation Plan

With formation of a carefully built team of committed agency staff, the next critical strategic 

step is to develop a plan for HSM implementation. A good plan addresses specific actions and 

assigns timeframes. It need not be overly detailed, but should be sufficient to communicate 

what needs to be done, in what order, and what issues will need addressing in completing each 

task. A good plan will recognize and respect the make-up of the organization and other known 

priorities. It will be ambitious but not overly so. Implementation plans should contain basic 

tasks such as training, organizational issues, revision of agency policies, risk management and 

legal issues, and information technology requirements. These are discussed in detail below. 

For an example of an HSM implementation plan, see the Florida DOT web site: 

http://www.dot.state.fl.us/safety/TransSafEng/HighwaySafetyManual.htm.

NCHRP 17-50, an AASHTO-sponsored HSM Lead State Initiative, kicked off in 2011 to support 

and encourage the implementation of the HSM. The project allows for sharing of lessons 

learned and a forum for discussion among states participating in the initiative. Lead and 

support states were identified. Lead states provide assistance to the support states. Exhibit 3 

shows the states participating in the project.
9

EXHIBIT 3

Lead States and Support States in the NCHRP 17-50 HSM Lead State Initiative Project

Examine and Revise Agency Policies

Implementation managers should lay out a roadmap, articulating a vision for how the HSM can 

over time influence how the DOT insures that safety is explicitly considered in all decisions and 

is incorporated into the overall project development process. The following are examples of key 

policies that some DOTs have begun to change based on HSM concepts or content:

• Program Prioritization – Use of HSM methods in agency planning and programming 

processes to identify “locations with promise” (i.e., black spots or high-crash locations); use 

of HSM values for CMFs to replace an agency’s crash reduction factors, and economic value 

of crashes, which is used as part of benefit/cost analyses. The Illinois DOT, for example, 

replaced their method for identifying high-accident locations with an HSM-based method 

used to identify roadway segments and intersections with significant opportunity for safety 

improvement and to develop their five percent reports to the FHWA.

• Asset Management – State programs are heavily influenced by use of data and analyses from 

their asset management systems. These include bridge and pavement management. The 
10

HSM offers the ability to add quantitative safety information into overall project 

programming, thereby redirecting or influencing the prioritization of projects based not 

only on asset condition and preservation but also safety performance.

• Warrants and Guidelines – Most state policies and manuals include warrants and guidelines 

for capacity and other improvements. Examples include “two-lane to four-lane” projects 

and grade separations to replace interchanges. The performance basis for such guidelines is 

typically mobility or operations-based. The HSM methods can be used to expand such 

guidelines to include threshold safety performance measures.

• Project Development – Incorporation of HSM concepts in project development decisionmaking process, including planning and programming, scoping, design criteria 

development, alternatives development, screening, and selection of preferred alternatives. 

This is done through revisions to DOT design manuals and reporting requirements, and is 

discussed in greater detail in the following section.

• Risk Management Processes – Design exceptions, deviations, and waivers are all fundamental 

design development processes. As discussed below, the HSM has direct application to how 

such processes are executed.

Revisions to policies or approaches will require much groundwork and coordination across 

offices and with the FHWA Division office. A well-thought-out roadmap will acknowledge 

limitations in data, and knowledge, and will produce a schedule that focuses on where early 

successes are most likely so that confidence is gained and benefits are immediately perceived.

Address Risk Management and Legal Issues

The team that produced the HSM over its 10-year development period included the former 

Chief Counsel for a state DOT, a current state DOT risk manager, and two university professors 

who served as risk management consultants to their state DOTs. The HSM was reviewed and 

vetted by the Transportation Research Board’s Tort Liability Committee. Managers should be 

assured that, as written and properly used, the HSM would not increase risk.

Concerns over tort liability are among the early questions and barriers raised by staff when they 

understand what the HSM is all about. Managers should anticipate these concerns and be 

prepared in advance to deal with them. The following are key strategies to incorporate:

• Be familiar with the specific tort issues in your state, and how these are currently 

communicated to DOT staff.

• Implementation managers and trainers should meet with the agency’s risk manager or chief 

counsel. Ideally, some risk management representation would be included in the core team. 

The HSM web site contains training materials that include key messages regarding tort 

liability, legal framework, what the HSM is (and is not), and names of DOT risk managers 

who worked on the HSM and can help develop deep understanding and comfort.

• Discuss the implications of the HSM on legal protections associated with USC 409 with chief 

counsel and data managers or IT staff. Take action to post appropriate notices, conduct 
11

training, and implement safeguards in the access to databases, and publication or use of 

data to retain the legal protections.

• Review and revise or strengthen as needed guidance to staff on how to write reports dealing 

with crash data and HSM methods. Such guidance would include what words should be 

avoided (e.g., “high-accident sites,” “hazardous locations,” “unsafe,” “unacceptable safety 

record,” etc.); how not to characterize a decision or proposed action, how to describe 

analyses and properly discuss potentially controversial subjects such as safety “tradeoffs.”

• Review current procedures for design exceptions reports, including the nature and type of 

documentation, who reviews and approves the analyses, what specific safety-based inputs 

are used, and how decisions are described and documented.

• Meet with FHWA Division staff to discuss design exceptions and how the process may 

change with application of the HSM. Make sure there is a common understanding and buyin prior to suggesting or implementing revised design exception processes.

• Review current internal training programs on design exceptions and risk management to 

seek opportunities to include information on the HSM; and where no such training exists, 

consider developing it as part of an overall safety and project development training 

initiative. Note that FHWA’s document “Mitigation Strategies for Design Exceptions”

which was written prior to publication of the HSM actually includes technical content on 

safety performance from the same research sources as were cited in the HSM.

Data and Data Systems

Data to support implementation include crash records, traffic volume data, roadway inventory

and traffic control data such as locations of signalized and stop-controlled intersections. As 

noted above, such data are typically maintained by different offices and different data 

management systems. For traffic volume and roadway inventory data the quality of the data 

may reflect other needs such as asset management systems. Data managers will need to 

understand the level of data quality needed to support HSM analyses. Investments in increased 

coverage or updating of data will need to be considered. For example, the agency may wish to 

consider expansion of intersection traffic volume counting programs. The extent of such 

investments should reflect and influence decisions about how the agency will adopt the HSM 

Part C predictive methods for their system (discussed below). The NCHRP Research Results 

Digest (2008) offers a reference to the data requirements to support the HSM.

Many questions need answering, such as: Who owns the data needed for implementation? (crashes, 

driver licensing, roadway geometry, design information, traffic data); Are the crashes georeferenced? How complete are the different data sources? Are data available for all roads in the state or 

just state-maintained roads? How often are databases updated? How can the agency integrate data 

sources geographically? Is the data infrastructure compatible across data sources? What are the 

resources – funding and staffing – needed to implement improved data and data systems?

Virtually all state HSM Implementation plans will include acquisition of data not already 

gathered. These may include additional traffic volume information, alignment data, and 

roadside condition data. In working with IT staff, the full vision of eventual data needs to be 
12

understood and accommodated. This may not occur for five years or more, but the technology 

requirements to be able to collect, maintain, and use all potential data need to be understood.

Information Technology

Most agencies do not currently maintain data systems robust enough to support full HSM 

analyses. Implementation of the HSM will require establishing close relationships with IT staff 

to outline what needs to be done to facilitate implementation. Many questions need answering, 

such as: How often are databases updated? Who has access to databases for analyses? What types of 

security are necessary to safeguard sensitive information? If consultants outside the agency are used 

routinely how will access to these data sources by their staff be managed? Are policies and procedures in 

place to accommodate for any liability and risk concerns that may exist? Is legal or risk management part 

of considerations related to implementation? Are there any existing tools in place at the agency? Are 

any other tools anticipated to support HSM implementation? How can the database infrastructure 

support seamless integration of these tools – is a phased approach necessary?

Development of Tools for HSM Implementation

The HSM contains presentation and documentation of models, and worksheets and 

methodology descriptions. Two types of tools will be needed for efficient application of the 

HSM – network screening tools and project-level design tools.

Many states are implementing SafetyAnalyst to serve as the basis for Part B HSM methods. 

SafetyAnalyst is a software tool which supports safety management decision-making by state 

and local highway agencies using state-of-the-art analytical methods. SafetyAnalyst was 

developed through an FHWA-pooled funds study and is now offered as AASHTO-Ware. 

Many states are implementing SafetyAnalyst to serve as the basis for Part B HSM methods. For

example, Ohio is currently using SafetyAnalyst to develop a new roadway safety management 

process. Working together with their IT department was critical in implementing the software. 

Assistance for states encountering technical difficulties in getting SafetyAnalyst to work is 

available through the service units for those licensing SafetyAnalyst or through FHWA for 

states considering licensing SafetyAnalyst. For project-level design analysis, FHWA’s 

Interactive Highway Safety Design Model (IHSDM) contains all Part C predictive models. 

IHSDM is a suite of software tools that support project-level geometric design decisions by 

providing quantitative information on the expected safety and operational performance. 

FHWA will continue the use of IHSDM as the support platform for Part C predictive models in 

future editions of the HSM. The IHSDM software is available for free download at 

http://www.ihsdm.org. The National Highway Institute (NHI) offers training in the IHSDM. 

For many applications such as small project or site specific analyses, simple spreadsheet tools 

will suffice. Some states are developing their own tools. NCHRP Project 17-38 produced a 

spreadsheet designed as a training tool; this has been adopted and refined by some states for 

their use. These spreadsheets can be downloaded from the AASHTO HSM web site: 

http://www.highwaysafetymanual.org.
13

Budgets for Implementation

Implementation efforts will require both staff time and other budgets. These will generally 

come from reallocation and deferral of other agency priorities. External assistance in many 

areas is available and thus should be considered. In addition to the Federal funding programs 

that would generally support research and implementation, State Planning and Research (SPR) 

funds, state training set-asides, and STP funding, other sources at the Division Office, such as 

technology transfer funding may be available to support implementation of the HSM.

Some states have undertaken their own research or development efforts for their own HSMtype tools. University partners can assist states here using funds to perform implementation 

tasks such as development of safety performance functions, benefit/cost tools, or conduct 

special studies of CMFs of interest to the state.

While the law (23 U.S.C. 148) and regulation (23 CFR 924) governing the HSIP lists 

transportation safety planning and improvement in the collection and analysis of safety data as 

eligible highway safety improvement projects, these activities must directly support HSIP 

implementation efforts. Activities supported with HSIP funds should address SHSP priorities, 

be supported by a data-driven process, and be used where they are likely to achieve significant 

reductions in fatalities and serious injuries.

States may leverage other federal-aid funds to support HSM implementation efforts. For 

example, state planning and research funds can be used to support data collection efforts. In 

addition, training is an eligible expense under core federal-aid programs. Improvements to the 

collection and analysis of safety data can also be funded by NHTSA Section 402 and 408 State 

Highway Safety Grant Programs.

Initiate HSM Training

Training of staff will undoubtedly be a part of any agency’s plan. Indeed, it tends to be among 

the first things discussed and conducted. Before signing up for training, review the agency’s 

plan for overall implementation. Focus on training materials that will address early action 

items. Lessons learned from states who were early recipients of training include the following 

insights:

• Resist the urge to train everyone initially or at once. Think strategically about which staff 

within the agency needs to learn the HSM first. This may be a select group of mid-level or 

senior managers or PMs; technical experts, and others who can be trusted to transfer the 

knowledge to others.

• Recruit and encourage senior leadership participation in at least part of the training to “set

the stage” and send a clear message that implementing the HSM is a top priority of the 

agency, and that it will be beneficial to them and their customers.
14

• Seek trainers who are capable of tailoring the training to the agency’s needs, systems, and 

terminology. DOTs that have invested a little money in tailoring the standard, available 

materials from NCHRP or FHWA have found staff understand better and are more 

receptive when they recognize references to their processes, data systems, manuals, etc.

• Consider commissioning different training for different staff within the agency. Most 

available core training materials address all four parts of the HSM. Training for planning 

and program staff, may best focus on the Part B materials and on the applications and use of 

SafetyAnalyst. Training of traffic engineering and design staff may best focus on Parts C 

(predictive methods) and D (CMFs).

• Include FHWA Division staff in training sessions, regardless of who the trainers are and 

whether Division staff has undergone their own training. Everyone will be working 

together and using the new materials. Having open discussions of how things will work, 

what assumptions will be needed, what approaches seem best will foster a cooperative 

learning environment and minimize conflicts in actual project settings.

• Incorporate into the training a module where the vision for implementation and the 

agency’s implementation plan are laid out and discussed. This can include the ongoing 

activities within the agency, timeframes, and individuals and offices included. This module 

can serve to solicit volunteers to be included in the roll-out of the new material.

A final important point regarding training involves the skills and capabilities and credibility of 

the trainers themselves. The HSM presents new safety concepts. HSM trainers must have 

sufficient fundamental knowledge of the new concepts, and be able to effectively communicate 

them. Among the more important concepts are why the use of crash rate is not the optimal 

approach, how to compute predicted crash frequencies using the Part C predictive methods, and 

how to incorporate both actual crash history and predicted crashes to compute expected crashes 

using the Empirical Bayes’ techniques. They also should be able to explain the relationship 

between Part D contents and FHWA’s CMF Clearinghouse.

FHWA has also recently released the Highway Safety Manual Training Guide as a resource 

document for state DOTs that are developing HSM training plans. It focuses on identifying 

HSM training currently available to state and local agencies who are considering 

implementation of the HSM, as well as identifying additional courses under development. 

Several training opportunities exist for highway safety and safety analysis, but the guide 

focuses only on courses directly applicable to content in the HSM and only those provided by 

NHI, FHWA, and ITE. The HSM training guide is available at 

http://safety.fhwa.dot.gov/hsm/training/hsmguide.pdf.

Develop Sustainable Technical Expertise

Agencies should have one or more staff at mid- to senior-level management with a deep 

understanding of what the HSM is and represents. Many states participated in research and 

development efforts for the HSM and FHWA companion projects such as SafetyAnalyst and the 

IHSDM. Such internal knowledge is helpful to explain benefits and value to the organization.
15

Most states will find it necessary to acquire additional expertise. Sources may include:

• Technical training of staff with their assignment as internal experts/resources;

• Retaining of on-call consultants with HSM expertise or background (this strategy can be 

stand-alone, or used as part of on-call contracting for traffic engineering or related services);

• FHWA Resource Center, Headquarters, and Division Office staff (for conducting of training 

and consultation on initial project applications); and

• Contracting with University resources who have demonstrated expertise in the HSM 

contents and concepts.

Such expertise can be used to help the DOT with certain aspects of implementation, or merely 

with review and analysis of projects as well as revision of policies. The AASHTO HSM User 

Discussion Forum, accessible through http://www.highwaysafetymanual.org, provides 

technical assistance to users. A number of support products, such as the HSM User Guide and 

the HSM Training Guide are currently under development. Once finalized and published, these 

documents will also be posted on the AASHTO HSM web site or a link to the particular 

document will be provided on the AASHTO HSM web site.

Technology Transfer to External Partners

Each agency’s plan should envision significant outreach to their partners within the state. 

County engineers, cities, and MPOs will all eventually need to implement the HSM on their 

system as well. Clearly, a state needs first to deal with its own data, staff, and systems. Given 

that in most states at least half the fatalities occur on the local system, outreach and cooperation 

will need to take place.

A well-thought-out plan envisions eventual institutionalization of the HSM, but recognizes the 

practical time and resource limitations. A common challenge is the limited technical expertise

and resources of county public works agencies. In many instances the county engineer may 

lack an engineering degree. Strategies to develop and nurture this outreach include:

• Inviting local agencies to attend HSM training, either as a separate group or with the DOT. 

(The Alabama DOT included a number of County engineers in their initial training in 2010. 

As part of this effort the county engineers were given copies of the HSM paid for by the 

state. This was a significant action, as the county engineers noted that they lacked budgets 

to purchase expensive manuals like the HSM.)

• Enlist the LTAP centers to develop and deliver training on proven, low-cost treatments as 

for country roads as documented in the HSM.

• Offer technical assistance either using DOT staff or consultants to work with and for the 

local agencies to apply the HSM methods on their programs, offer additional investments in 

data acquisition and management to local agencies so that their system can be evaluated in a 

manner consistent with that of the state system.
16

Organizational Needs and Issues

The implementation team will need to make decisions regarding what fundamental approaches 

will be followed in actual implementation of the HSM. These decisions should reflect full 

understanding of not just initial work, but continuing upkeep and maintenance of the system; 

the organizational structure of the agency; and business processes.

Implementation actions, timing and needs will vary depending on the organization’s size, 

structure, and operations. State DOTs can be broadly characterized as either centrally focused 

or decentralized. In the former, programs are built and projects managed at the Central Office. 

Geographic responsibilities may be limited to maintenance and operating regimes. In the latter 

instance, District or Regional staff may be located throughout the state, with professionals 

building their own programs (following Central Office-driven policies and procedures) and 

managing their own projects.

Clearly, in the case of decentralized operations the time to successfully implement a new 

technology or procedure will be greater. This is not just a function of resources but also of 

reaching professional staff, conducting training and outreach, and in many cases “persuading”

them to adopt the new methods. Lessons learned from one lead state, the Illinois DOT, suggest 

that early positive engagement with regional staff is important, as is patience in rolling out the 

new approaches. Also, offering “hands-on” assistance to staff through development of tools, 

making technical resources (DOT staff, on-call consultants) available, or other measures also is 

important. Finally, seeking out and working directly with District “champions” can help sell 

the new approaches. This mirrors the “Lead State” approach FHWA and AASHTO promote.
17

3. HSM Implementation Opportunities in 

Program Development and Project Delivery

The core mission of state DOTs and other similar agencies is to develop and manage a 

transportation system. Managers explaining and promoting the HSM will find that explaining 

its potential use in the context of the project development process in their state will resonate 

with staff. The emphasis here should be on all projects and all activities, not just those that refer 

to “safety.” Most projects that comprise a state’s program are not “safety projects” but rather are 

prioritized for other reasons. Regardless of the project’s purpose and need, the HSM offers 

benefits and can be used in the delivery of the overall program and each project.

FHWA also maintains a Crash Modification Clearinghouse. HSM content on crash modification 

factors (CMF) is in Part D. As research continues and the knowledge base grows, agencies will 

want to take advantage of HSM-quality CMF research. The FHWA Clearinghouse 

(http://safety.fhwa.dot.gov/tools/crf/resources/) is a core tool that most states are using.

Exhibit 4 shows a typical project development process and opportunities to implement the 

HSM. The following is an overview of how implementing the HSM can influence program and 

project delivery. As training progresses and policies are changed, eventually actual project 

applications will gradually become the norm for the agency’s delivery process. Strategies and 

insights for successful project delivery implementation are included in each section.

Program Development

The Federal Aid Highway Program includes a portion of every state’s allocation specifically set 

aside for safety improvements. Within each state program, these funds are subject to a formal 

prioritization process that takes into account crash history and exposure. The HSM can enhance 

the effectiveness of that prioritization process, as well as providing data to support the 

allocation of additional state and Federal funding to address safety needs.

The HSM offers improvements over many agencies’ historic approaches to the Highway Safety 

Improvement Program (HSIP). For example, HSM methods and concepts from Part B were 

incorporated within the Illinois DOT’s process for developing their “Five Percent Report” to the 

FHWA. Over time, the HSM-based methods were refined and found so valuable that the report 

replaced Illinois DOT’s old methodology for identifying safety projects. Illinois DOT District 

staff was at first encouraged to use the data and methods in Parts B and D, and eventually 

required to use them to have their HSIP projects funded. IDOT developed a benefit/cost tool 

with CMFs to staff. The tool, using HSM values for CMFs, supports consistency in approach 

and a high degree of confidence.
18

EXHIBIT 4 The Project Development Process and Opportunities to Implement the HSM
19

A lesson learned from this exercise involves the use of consistent approaches to CMF 

applications at the state program level. The published HSM is dated to 2007. FHWA’s CMF 

Clearinghouse is kept current with published CMF research. The Clearinghouse may contain 

multiple CMF studies with differing values for the same treatment or countermeasure. State 

managers need to recognize and address the issue of who decides which CMF is appropriate, 

what constitutes a minimum level of technical acceptability to the agency and how to keep the 

agency’s list of approved CMFs current as more are added to the Clearinghouse.

Another decision and action to take includes how crashes and their outcomes will be valued. 

The HSM offers the “willingness to pay” approach to valuing crashes and severity, but there are 

other methods used (including a different valuation used in AASHTO’s RSAP program for 

roadside design). Again, a common and consistent approach should be determined and then 

communicated as part of program development guidance and documentation.

Project Development

The HSM also offers opportunities to influence how agencies develop individual projects. Early 

in project development, key decisions are made that influence how the project will be 

completed. These include defining project scoping, project purpose and need, project 

objectives, and from all of these, which “track” the project will follow. In later stages, as the 

project takes shape, detailed studies establish the basic footprint and attributes of the project.

Actual implementation of the HSM within projects should be planned in cooperation with 

Districts and project managers. As an example, Florida DOT instituted a pilot program with its 

Districts, in which specific projects typical of the District’s work were identified and HSM 

methods tested. District involvement in the identification of projects and assistance of the HSM 

team in data gathering, coding, and interpretation of the results produced understanding and 

buy-in to the process and tools. Implementing agencies may consider working with one or two 

Districts with strong champions and interest, establish the process, and then extend it to other 

Districts.

Project Scoping and Design Criteria

At project initiation, agencies conduct a project scoping exercise. This includes all offices 

concerned with any aspect of the project, as well as external partners such as the FHWA. 

Project objectives, project limits, and coordination activities are discussed and established.

Project scoping decisions and establishment of design criteria can have a significant influence 

on the cost, physical feasibility, and ultimate value of a project. Direct incorporation of HSMbased analyses as part of agency scoping offers significant cost-saving potential without 

degrading overall safety performance.
20

Many projects involve an existing facility. For such projects that are not envisioned to include 

major lane or capacity additions, the safety performance of the existing facility can play an 

important role in defining the scope of the project.

Scoping Using the Two Dimensions of Safety

Existing highways, intersections, and streets will have crash records, traffic volume data and 

known geometric features. Agencies that have implemented the HSM will have predictive 

methods that can provide insights on how the existing safety performance (substantive safety) 

is relative to a threshold representative of other sites with similar characteristics. The threshold, 

established by the agency with reference to the HSM methods, quantifies the anticipated 

average performance of a typical site to identify potential for improvement. The comparison 

answers a basic question – Is this site/project performing as or better than expected in terms of the 

number and severity of crashes (Yes or No)?

The second dimension of safety, its nominal safety, is straightforward to understand. Given the 

design characteristics of the facility, does it meet current design criteria and standards of the 

agency or not? (Or perhaps more precisely, to what extent and for what geometric features is the 

location either “nominally acceptable” or not?). Armed with these simple answers an agency could 

as a matter of project development policy implement a performance-based design decision 

approach across the two dimensions of safety.

There are many reconstruction projects in which one or more geometric features do not meet 

current criteria and standards. This case is very typical of roads designed and constructed more 

than 30 years ago when design standards were much different. If the existing safety 

performance record meets or exceeds (is better than) the agency’s threshold of acceptability, the 

agency may reasonably and confidently scope the project as a 3R project, retaining the basic 

geometry and thus avoiding incurring of potentially substantial construction costs as well as 

avoiding or mitigating environmental conflicts and additional right-of-way acquisition. The 

key insight is that applying HSM knowledge can prevent costly investments made in the name 

of safety when no actual benefit or return from such investments should be expected.

Purpose and Need

The identification of the fundamental reason for the project – its “purpose and need” is among 

the most important project drivers. This should be a performance-based determination, 

whether the problem is pavement or bridge condition, delay, travel time or level of service, or 

safety. Clearly, the HSM offers the best means of establishing a science-based and hence 

defensible approach to defining whether the performance of the facility merits “safety” being 

mentioned as part of its purpose and need.
21

Project Planning, Alignment, and Alternative Studies

HSM methods and concepts have clear application to development of project alternatives. 

Indeed, the forerunner of the HSM, FHWA’s Interactive Highway Safety Design Model, which 

executes through software the predictive methods in Part C of the HSM, is an interactive tool to 

be used during the design process to iterate and understand implications of design decisions in 

the same way that cost analysis and estimation tools are used to understand differences in 

quantities and construction costs. Applications apply not only to projects involving the same 

highway type, but also studies in which a different type is envisioned. The best example of 

these is conversion of an existing two-lane highway to a multilane facility. Such projects often 

involve multiple alignments and can include different cross sections.

One insight gained through training sessions of state DOT staff is that the manner in which 

Part C can be used may vary. In fact, many designers may never actually use the HSM to 

calculate the anticipated long-term safety performance of a site such as the one being designed 

(predicted average crash frequency) or the long-term performance of an existing site (expected 

average crash frequency). But merely using the HSM Part C as a reference, designers can easily 

gain insights on the relative safety performance of design alternatives they typically consider, 

and adjust their thinking about how to make good design decisions.

The training of designers has focused, for the most part, on the importance of nominal safety. 

Many designers have been taught that adherence to nominal safety directly translates into 

substantive safety performance. The following list presents general understanding by designers 

unfamiliar with the highway substantive safety knowledge base in the HSM:

• Many designers overestimate the relative importance of 0.5-foot or 1-foot differences in lane 

width to substantive safety on two-lane rural highways;

• Many designers overestimate the effect of relatively minor changes in alignment on crash 

frequency;

• Many designers lack the ability to assess the order of magnitude of expected crash 

frequency (the long-term anticipated average project safety performance) as a function of 

traffic volume; and

• Many designers assume that the design criteria in the AASHTO Policy on Geometric Design 

are based on safety performance, and that even modest changes in design dimensions carry 

significant safety risk.

Managers can encourage designers to learn and apply the HSM knowledge base even if they 

will not actually apply the predictive methods. In doing so, the quality of their work will be 

greatly enhanced. The ability of a designer to consider substantive safety is strongly dependent 

on a sound understanding of HSM concepts and the science of safety captured in Part C of the 

HSM (predictive method) and positive guidance principles described in Chapter 2 of the HSM. 

The National Highway Institute has a number of courses that has more of a road design focus:
22

• HSM Applications to Two-Lane Rural Roads (FHWA Resource Center Webinar);

• HSM Applications to Urban/Suburban Intersections (FHWA Resource Center Webinar);

• HSM Applications to Rural Intersections (FHWA Resource Center Webinar);

• HSM Applications to Multilane Highways (FHWA Resource Center Webinar);

• HSM Application to Urban/Suburban Roads (FHWA Resource Center Webinar);

• HSM Applications to Rural Multilane Intersections (FHWA Resource Center Webinar);

• HSM Applications to Horizontal Curves (FHWA Resource Center Webinar); and

• HSM Relationship to Roadway Departure Crashes (FHWA Resource Center Webinar).

Also, AASHTO produced a three-hour webinar on Flexibility in Design that provides 

background on the relationship of design criteria to performance and offers insights on design 

decision-making in reconstruction.

Application of the HSM in day-to-day activities should follow training as soon as possible. 

Direction and technical assistance may be necessary during these initial efforts to use the HSM.

The extent to which the HSM can be immediately used following training to inform the design 

process depends on several factors. With state-specific calibration factors or state-specific SPFs 

already available, designers can quantify actual long-term expected safety performance of a 

facility, considering both the number and severity of crashes.

Several states are currently in the process of calibrating HSM Safety Performance Functions 

(SPF) and the development of state or region-specific SPFs. During this development period, 

designers can still use the HSM Part C to assess relative differences among alternatives within 

the same facility type and control type. However, the output from an HSM SPF cannot be used 

or described as an actual prediction, as it lacks the necessary calibration factor. Calibration of 

the HSM SPFs is necessary for full predictive capability because the SPFs in the HSM are based 

on the data from a subset of states. Differences in crash data quality, roadway inventory data, 

traffic volume counts and estimations, minimum crash reporting thresholds, topography and 

weather conditions are but some of the factors that vary among states that may impact the 

number and severity of crashes.

Managers will need to weigh the advantages and disadvantages of promoting the immediate 

use of the HSM and the timing of delivery of training for staff in states with SPF or calibration 

development efforts that may take some time. Rather than hold off on training or any use of the 

HSM, the identification of implementation opportunities before the training would be useful. 

The training can then include some discussion of the particular approach that the agency will 

take in terms of implementation of the HSM in the project development process.
23

Design and Context Sensitive Solutions

In many projects, conflicts can occur between what a designer may perceive as the best design 

(i.e., one that is nominally safe) and what may be achievable due to environmental constraints 

or conditions, public acceptability and availability of right-of-way. Context Sensitive Solutions 

as outlined by AASHTO and NCHRP Report 480 addresses these four critical success factors:

• Employ effective decision-making;

• Reflect community values;

• Achieve environmental sensitivity; and

• Deliver safe and feasible solutions.

Virtually all aspects of project development have evolved to state in which DOTs can provide 

quantitative, high-quality data on the performance of an alternative, with the exception until 

now of safety performance. Indeed, the extent of safety analysis frequently applied to 

contentious or difficult projects is the nominal safety model. With HSM methods and 

approaches, agencies can better fill in the missing piece and not only make better decisions but 

have the basis for explaining and defending their decisions.

The final step in the initial planning part of the project development process is identification of 

a preferred design alternative. This is typically done when design is about 30 percent complete, 

i.e., when the alignment and cross section are established. The HSM can then be used to perform 

predictions of safety performance compared to other alternatives, or to a “no-build” option.

Preliminary and Final Engineering

As the selected concept is detailed, changes may occur. Other major design decisions such as 

maintenance of traffic plans are developed. During preliminary engineering the design 

documentation is prepared and approvals sought. It is during this stage that design exceptions 

may be fully outlined, studied, and approved.

Design exceptions – the use of a design value outside the established criteria for the project, are 

a common and indeed routine part of project development. A design exception represents an 

acceptance that the design will not be “nominally safe.” Some designers and some agencies 

resist design exceptions either because of tort liability fears or their genuine belief that safety 

performance (substantive safety) will be compromised.

The HSM offers concepts and methods for design engineers to understand the implications of 

their actions and thus improve decision-making. Insights evident in applying the predictive 

methods and CMFs, include the following:
24

• Traffic volume is an important determinant of relative risk. A design exception on a road 

with 1,000 vpd will clearly have less risk than one with a volume of 10,000 vpd;

• The length of highway over which the exception occurs strongly influences relative risk; and

• The design element or feature in question (lane width, shoulder width, superelevation, 

curvature, grade) will have differing expected sensitivities based on the type of facility.

Designers attuned to the nominal safety model but not to the contents of the HSM may have a 

mindset that any change of a standard design parameter would result in a significant change in 

the safety performance of the facility. For example, a reduction in lane width from 12 feet to 

11 feet may thought to be reducing safety performance substantially in an abrupt and 

immediate manner, i.e., the change makes the facility unsafe and 12 feet made the facility safe. 

Actual or substantive safety performance is, however, does not represent such an absolute 

change in safety but rather a gradual change in safety. It is important to keep in mind that such 

a relationship with substantive safety may not even exist. Designers who have learned about 

substantive safety, and marginal or incremental changes in safety performance suggested by 

CMFs and predictive models, will understand the change in safety is likely gradual and be able 

to act accordingly. Several states that started with the implementation of the HSM reported that 

the HSM adds value to the evaluation of design exceptions and the documentation process.

Besides allowing designers to quantify the impact of design exceptions, the HSM also offers the 

opportunity to quantify potential safety performance benefits of mitigation strategies at 

locations where design exceptions are considered. The FHWA Mitigation Strategies for Design 

Exceptions (FHWA 2007) offers a resource to design managers.

Operations and Maintenance

The HSM includes information to inform those charged with operating and maintaining the 

system. Full knowledge and application of the HSM contents in this area may lead agencies to 

rethink or revise their operating strategies. Examples may include incorporating quantitative 

safety consideration when timing of signals (provision for protected only left-turn phasing), 

considering access management strategies, decides when to allow or prohibit of on-street 

parking, and even maintenance in adverse weather conditions: snow removal strategies.

Managers studying the HSM may find that the 1st edition of the HSM is limited in offering 

quantitative safety information for all operations and maintenance activities. As with the first 

edition of the Highway Capacity Manual (HCM), the expectation is that over time, the HSM 

will be updated to reflect the growing body of research on the impact of maintenance and 

operational effects on crash frequency and crash severity.
25

4. Summary

Agency officials often cite safety as their top priority. With the adoption and use of the HSM, 

states may be in a position to evaluate, program, design, and construct facilities with an 

understanding of their quantitative safety performance. The investment by AASHTO and 

FHWA in the development the HSM was driven by a belief that improved scientific knowledge 

of safety performance would produce significant benefits. Such benefits go well beyond 

projects or programs that are “safety-based,” but rather all projects and all activities.

Deriving full value from the HSM will only occur if states and other agencies adapt their 

organizations and business processes to enable its implementation. Careful planning and 

management of an implementation effort is necessary. In addition to completing obvious tasks 

such as training, database development and management, agencies will want to examine their 

internal program and project development policies and risk management procedures. Finally, 

states should anticipate the need to engage their project delivery staff in a dialogue on the 

reasons for implementation, with specific emphasis on the benefits that will be achieved for the 

agency and their customers.

DOT managers charged with policy and program development, staff development, and 

ultimately accountability to their customers should make every effort to assist their agency and 

partner agencies in the development and execution of an HSM implementation program.
26

5. References

AASHTO, 2010. The Highway Safety Manual, American Association of State Highway 

Transportation Professionals, Washington, D.C.

Hauer, E., 1999. ITE Traffic Safety Toolbox Introduction, Washington, D.C.

FHWA, 2007. Mitigation Strategies for Design Exceptions, July 2007, Report No. FHWA-SA-07-

011, Washington, D.C., http://www.wsdot.wa.gov/publications/fulltext/ProjectDev/

Manuals/MitigationManual.pdf.

NCHRP, 2008. Highway Safety Manual Data Needs Guide, National Cooperative Highway 

Research Program, NCHRP Research Results Digest 329, June 2008, Washington, D.C., 

http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_rrd_329.pdf.

Neuman, T.R., Schwartz, M., Clark, L., and Bednar, J., 2002. A Guide to Best Practices for 

Achieving Context Sensitive Solutions, NCHRP Report 480, Washington, D.C., 

http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_rpt_480.pdf.
27

6. Resources

On-Line

HSM – http://www.highwaysafetymanual.org.

IHSDM – http://www.ihsdm.org.

SafetyAnalyst – http://www.safetyanalyst.org/.

Introduction to the HSM Video produced by AASHTO: http://bcove.me/hbct8mxu.

FHWA Crash Modification Factors Clearinghouse: http://cmfclearinghouse.org.

Publications

FHWA, 2011. HSM Training Guide, Federal Highway Administration: Office of Safety, 

http://safety.fhwa.dot.gov/hsm/training.

NCHRP Synthesis 316, Design Exception Practices, http://trb.org/publications/nchrp/nchrp_

syn316.pdf.

NCHRP Research Results Digest 306, Identification of Liability-Related Impediments to Sharing 

Section 409 Safety Data Among Transportation Agencies and A Synthesis of Best Practices, 

http://trb.org/publications/nchrp/nchrp_rrd_306.pdf.
28

7. List of Acronyms

AASHTO American Association of State Highway Transportation Officials

CMF Crash Modification Factors

DOT State Department of Transportation (a general term used to describe the state 

agency that is responsible for the design and maintenance of the state 

transportation highway network)

FHWA Federal Highway Administration

HCM Highway Capacity Manual

HSIP Highway Safety Improvement Program

HSM Highway Safety Manual

IHSDM Interactive Highway Safety Design Model

ITE Institute of Transportation Engineers

NCHRP National Cooperative Highway Research Program

NHI National Highway Institute

RSAP Roadside Safety Analysis Program

SPF Safety Performance Functions

SPR State Planning and Research

TRB Transportation Research Board

VPD Vehicles per Day
Federal Highway Administration

Office of Safety

1200 New Jersey Avenue SE

Washington, DC 20590

FHWA-SA-11-48