The National Academies

NCHRP 17-27 [Completed]

Parts I and II of the Highway Safety Manual

  Project Data
Funds: $530,520
Research Agency: iTrans Consulting Ltd
Principal Investigator: Geni Bahar
Effective Date: 5/14/2004
Completion Date: 6/30/2007


An extensive and ground-breaking initiative is underway to develop a Highway Safety Manual (HSM). Development of the HSM was initiated by a Transportation Research Board Joint Subcommittee (now Task Force). Portions of the Manual are being developed under several NCHRP projects and the HSM will be recommended for adoption by AASHTO. The HSM will serve as a tool to help practitioners make planning, design, and operations decisions based upon safety. It will serve the same role for safety analysis that the Highway Capacity Manual (HCM) serves for traffic operational analysis. The purpose of the HSM will be to provide the best factual information and tools in a useful and widely accepted form to facilitate the explicit consideration of safety in decision making. Development of the HSM will be a significant and lengthy effort; it is detailed in the HSM work plan (the plan and other documents related to the HSM are located on the TRB HSM Task Force website noted under Task 1 below). The related NCHRP projects are shown in the following table.

Committed Projects
HSM Part
Scope of Work
Status as of 1 Sept. 2003
NCHRP Project 17-18(4) Part III, Chapter 8 Develop HSM annotated outline, prototype chapter (two-lane rural roads), and work plan Completed
NCHRP Project 17-26 Part III, Chapter 10 Develop urban and suburban predictive model Start: June 2003, 24-month contract
NCHRP Project 17-29 Part III, Chapter 9 Develop multilane rural predictive model RFP advertised, proposals due to NCHRP on October 2, 2003
NCHRP Project 17-27 Parts I and II, Chapters 2 - 7 Develop Part I and Part II RFP advertised, proposals due to NCHRP on November 13, 2003

Other NCHRP projects are focused on developing the safety prediction models or algorithms needed to make quantitative estimates of safety performance for specific highway types. These initial modeling efforts are expected to result in substantial change in the approach to highway safety analyses. Enhancements to the models are expected to be included in future editions of the HSM.

Part I (Introduction and Fundamentals) of the HSM will introduce the manual and provide an overview of its functions and applications and will present some highway safety fundamentals for the user. Part II (Knowledge) will present a summary of information on safety effects of various aspects of roadway design and operation in a form that users can readily apply to their work. Parts I and II will also provide essential material to allow users to understand and apply the quantitative estimation procedures in Part III effectively.

HSM Part I (Chapter 2) and Part II will be developed in this project in as near final form as possible. NCHRP Project 17-18(4) developed an outline of the HSM and the TRB Task Force is developing Part I, Chapter 1. The project will maintain liaison with ongoing research projects such as those in the above table and FHWA's "Interactive Highway Safety Design Model" (IHSDM); FHWA's "SafetyAnalyst"; NCHRP projects to develop a Human Factors Guide; AASHTO's Transportation Safety Information Management System (TSIMS); and AASHTO's implementation of its Strategic Highway Safety Plan.


The objective of the research is to prepare Parts I (Chapter 2) and II (Chapters 3-7) of the Highway Safety Manual.

Accomplishment of the project objective will require at least the following tasks.

(1.) Review the Highway Safety Manual (HSM) production documents, including but not limited to the following:
  • HSM work plan,
  • HSM annotated outline, and
  • HSM prototype chapter.
(2.) Review guidance available from the HSM Task Force, including but not limited to the following:
  • Research quality control and research acceptance procedures,
  • Measures for quantifying highway safety effectiveness,
  • Survey of potential users, and
  • HSM chapter format.
(3.) Conduct a review of completed and ongoing research (domestic and international) related to the chapters that will be developed in this project. This comprehensive task provides the knowledge base for Part II and will provide useful information for other parts of the HSM. (4.) Develop criteria for assessing the validity and applicability of the literature results reported. These criteria may include materials from the HSM Task Force procedures on research quality control and acceptance, and previous and ongoing NCHRP and FHWA research. The criteria shall be submitted to NCHRP for approval. (5.) Apply the criteria developed in Task 4 to the literature sources identified in Task 3 and select those considered appropriate to use. (6.) Review and revise the annotated outline for Parts I (Chapter 2 only) and II, including the identification of the source documents. (7.) Prepare an interim report that summarizes the results of Tasks 1 through 6 and includes the annotated outline developed in Task 6. The interim report shall also identify the prototype chapter that will be developed in Task 9. (8.) Meet with the NCHRP panel to review the Task 7 interim report approximately 2 months after its submittal. After the meeting, the contractor shall provide a written response to the review comments and decisions at the meeting. (9.) Prepare the selected prototype chapter for Part II, for review by the NCHRP and the HSM Task Force. (10.) Meet with the NCHRP panel to review the Task 9 prototype chapter approximately 2 months after its submittal. After the meeting, submit a revised chapter addressing the review comments and decisions at the meeting. (11.) Develop the remaining chapters. (12.) Submit a final report documenting the entire research effort. The final report shall describe how the project was conducted and identify areas for further research that is needed to fill gaps. The report shall include as appendices the chapters for inclusion in the HSM.

Status: Drafts of chapters 2 through 7 for the Highway Safety Manual (HSM) have been completed and copies provide to the Project 17-36 contractor for production of the first edition of the HSM. 

Product Availability: Draft copies of Chapters 2 through 7 of the Highway Safety Manual.

To create a link to this page, use this URL: http://apps.trb.org/cmsfeed/TRBNetProjectDisplay.asp?ProjectID=453