The National Academies

NCHRP 17-71 [Active]

Proposed AASHTO Highway Safety Manual, Second Edition

  Project Data
Funds: $1,200,000
Staff Responsibility: Mark S. Bush
Research Agency: Kittelson & Associates, Inc.
Principal Investigator: Erin M. Ferguson
Effective Date: 10/12/2015
Completion Date: 1/31/2021

The AASHTO Highway Safety Manual (HSM) is rapidly becoming a key safety management and evaluation tool for state and local highway agencies; MPOs; and the safety, design and traffic engineering professional community. The HSM was developed largely through NCHRP research and the First Edition was published in 2010. As the First Edition was being developed, it was clear that high-priority research could not be completed without delaying publication. An example is the safety prediction models for freeways and interchanges developed under NCHRP Project 17-45--while this research is important, the decision was made to publish the First Edition without this material. Several other research efforts to develop models for additional facility types for inclusion in the HSM are underway and, like the freeways and interchanges chapters, each are considered critical to increasing safety knowledge and practice. The HSM has fostered significant advances in analytical methods in highway safety and this evolution continues; with increased knowledge, Safety Performance Functions (SPFs) and Crash Modification Factors (CMFs) being developed on an ongoing basis. Users and researchers now have gained experience with the HSM and have outlined priorities for enhancements to HSM chapters, procedures, and models. An example of current research that could be included in the next edition is an FHWA decision tree used to determine whether to develop a state-specific safety performance function or to calibrate the functions provided in the HSM. Beyond applying the HSM in specific situations such as network screening, crash diagnosis and design exceptions, state departments of transportation and other users are developing their own safety performance functions, policies, agency-wide training programs and pursuing other implementation activities that more completely integrate the information in the HSM. With the implementation of the existing HSM, errors and misunderstanding of appropriate applications have been noted. With increasing knowledge and the growing experience of the HSM user, additional needs are continuing to be identified. These needs have led to a significant amount of combined research through NCHRP, FHWA, and pooled fund initiatives. This research is further developing and promoting the quantitative, data-driven approach to safety. These research efforts are not specifically developing new chapters for the HSM or enhancing models already in the manual, but are expected to result in advances that are suitable for inclusion in the next edition HSM or other AASHTO documents such as the AASHTO “Green Book.” Incorporating this material throughout the HSM will take specialized knowledge and research skills in order to appropriately identify, evaluate, refine and include this research in a manner suited to practitioners. The HSM Second Edition will represent an important advance in safety management and support the expanding evaluation capabilities of highway agencies.

The objective of this research is to develop and prepare a proposed Second Edition Highway Safety Manual (HSM) in a format suitable for adoption as an AASHTO publication. The proposed Second Edition will synthesize and incorporate relevant ongoing and completed research, related documents, and user feedback in order to expand the scope and quality of the HSM to increase application and improve the usability by way of the Second Edition HSM.

The research will be accomplished in four primary phases with two planned face-to-face interim meetings with the panel and research team. Each primary phase is contingent upon NCHRP approval of the previous phase results.
The research plan should include, as a minimum, the following components and are anticipated as a suggested overall framework of the proposed research:
  • Review the existing HSM for errors, inconsistencies, and duplications in addition to the published errata.
  • Identify gaps, needed expansions and changes to current chapters, such as Chapter 2, “Human Factors in Road Safety,” Chapter 3, “Fundamentals,” Appendix A of Part C, Calibration Factor procedures, and others.
  • Develop a plan to obtain user feedback including but not limited to consulting with the AASHTO Standing Committee on Highway Traffic Safety (SCOHTS), Subcommittee on Safety Management (SCOHTS-SSM), specifically with its Task Group on Technical Safety Publication Oversight and Outreach, and the TRB Highway Safety Performance Committee (ANB25) to identify key issues to be considered in preparing the Second Edition of the HSM.
  • Identify and assemble the research results and related HSM materials that should be considered for inclusion to the Second Edition HSM.
  • Compile a list of broad-based issues, action plan, and proposed changes for review by the NCHRP Panel. These would include, as a minimum:
1.     changes based on research and recently completed chapters,
2.     identification of critical gaps in knowledge or gaps in the available HSM materials that have not been addressed. Note: These may include any material in the first draft that has not yet been updated (e.g., computational examples), and
3.     an action plan with recommendations to fill those gaps either with materials expected from ongoing research or with research to be conducted as part of this research effort.
  • Conduct the research needed to fill the gaps identified in the earlier task. Note: Research conducted by the research contractor is expected to fill small gaps and resolve inconsistencies in available materials, since large gaps are expected to be addressed in other ongoing identified funded research.
  • Develop a comprehensive initial first draft of the updated HSM incorporating the new results and new HSM materials and expansions to current chapters, and edit the draft to incorporate user feedback. Coordinate at a minimum with the AASHTO Safety Management Subcommittee (SCOHTS-SSM), and its Task Groupon Technical Safety Publication Oversight and Outreach, and the TRB Highway Safety Performance Committee (ANB25). The research contractor will gather feedback and consolidate comments from AASHTO and TRB and provide to NCHRP for panel review.
  • Obtain materials from all HSM-relevant related research that has been completed during the project period, and develop a second draft of the updated HSM incorporating those new materials, as well as revisions in response to comments on the initial first draft and the results of research completed.
  • As part of the development of the second draft, prepare and/or update computational examples that illustrate the intended application of HSM methodologies, and include the results of any needed small research efforts to close gaps or inconsistencies between the new material and existing material. Provide the second draft for NCHRP review to the AASHTO Safety Management Subcommittee Task Group, and the TRB Highway Safety Performance Committee. The contractor will receive feedback and consolidate comments from AASHTO and TRB and submit the results to the NCHRP. The NCHRP will vet the consolidated comments to the panel and provide feedback to the research team.
  • Develop a preliminary final draft of the updated HSM for review by NCHRP, AASHTO Safety Management Subcommittee Task Group, and the TRB Highway Safety Performance Committee. The contractor will receive feedback and consolidate comments from AASHTO and TRB and submit the results to NCHRP. The NCHRP will vet the consolidated comments to the panel and provide feedback to the research team.
  • Incorporate recommended changes and comments from the NCHRP panel into a final draft edition HSM report suitable for AASHTO publication. Develop a comprehensive list of items to be excluded from the HSM Second Edition and justifications. Document and log changes that also include the feedback received throughout the duration of this research between the existing HSM First Edition and the development of the new Second Edition HSM. Provide final version of the Second Edition HSM to AASHTO for balloting and eventual publication.
In addition to standard monthly and quarterly progress reports required throughout the duration of the research, two face-to-face interim meetings shall be planned.The research agency shall not begin work on subsequent phases without NCHRP approval.
At the completion of Phase 1, a Phase 1 Interim Report shall include at a minimum:
1.     User feedback summary and framework for the proposed changes to the HSM.
2.     List of errors, gaps, and modifications to current text that includes corrections beyond published errata and new chapters already completed, and proposed expansions to current chapters.
3.     Updated work plan for Phase 2.
At the completion of Phase 2, a Phase 2 Interim Report shall include at a minimum:
1.     A comprehensive first draft of HSM incorporating all approved changes in Phase 1.
2.     List of proposed changes to the first draft based on review comments, including identified gaps, new and ongoing research and recently completed chapters.
3.     Identified gaps in content and possible immediate remediation measures.
4.     Updated work plan for Phase 3.
At the completion of the Phase 3, a Phase 3 Interim Report shall include at a minimum:
1.     A comprehensive second draft of HSM incorporating all approved changes in Phase 2, and any remediation measures.
2.     A comprehensive third draft of the HSM incorporating the small research gaps incorporating all comments and items approved by NCHRP.
At the completion of the research, the final deliverables at a minimum shall include:
1.     A final report documenting the conduct of research that also includes an executive summary and the research team’s recommendation of research needs and priorities for future related research and future HSM editions. As part of the final report, an appendix listing items excluded from the Second Edition HSM and a justification of each item. Also as part of the final report, an appendix documenting all the log changes and feedback received between the First Edition HSM and new Second Edition HSM.
2.     A stand-alone final version of the Second Edition HSM ready for AASHTO balloting and publication.
3.     A PowerPoint presentation describing the project background, objective, research method, findings and conclusions that summarizes the project for an executive or management level audience.
The research plan shall provide a 1-month period of review and approval of each phase interim report covering at a minimum the items above. Two face-to-face interim meetings of the project panel with the research agency will be required. Each face-to-face meeting will be coordinated by NCHRP at a suitable NAS facility location and time most convenient for the research team and panel.  The research plan should build in appropriate checkpoints with the NCHRP project panel including at a minimum, (1) a kick-off web teleconference meeting to be held and hosted by the research team within 1 month of the contract’s execution date and (2) in addition to the two face-to-face phase interim report review meetings, web-enabled teleconferences tied to panel review and NCHRP approval of any other interim deliverables deemed appropriate.
STATUS: Research in progress; continuation request approved.

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