Developing Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects (2021)

Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

xi Summary This report presents the results of research to develop improved design guidelines for resurfacing, restoration, and rehabilitation (3R) projects. These guidelines were developed to replace the older guidance presented in TRB Special Report 214. The guidelines were developed based on the results of a literature review, a highway agency survey, discussions with design and safety practitioners, and review of the results of benefit–cost analysis results for design improvement type typically included in 3R projects. The guidelines focus on a key design decision concerning which potential 3R projects should be resurfaced with, and which potential 3R projects should be resurfaced without, accompanying design improvements. The guidelines take a performance-based approach to this decision considering existing roadway and roadside features, traffic volumes, and crash history. The crash reduction effectiveness of potential design improvements is based primarily on the crash prediction methods from the AASHTO Highway Safety Manual. The performance-based approach uses benefit–cost analysis to focus the limited funding available for design improvements on the projects where the greatest crash reduction can be achieved. For any given level of expenditure on design improvements in 3R projects, the performance-based approach should provide greater crash reduction benefits than any set of dimensional geometric design criteria. The guidelines suggest that design improvements should be made as part of 3R projects in the following situations:  An analysis of the crash history of the existing road identifies one or more crash patterns that are potentially correctable by a specific design improvement,  An analysis of the traffic operational level of service (LOS) indicates that the LOS is currently lower than the highway agency’s target LOS for the facility or will become lower than the target LOS within the service life of the planned pavement resurfacing (typically 7 to 12 years), or  A design improvement would be expected to reduce sufficient crashes over its service life to be cost-effective; i.e., the anticipated crash reduction benefits over the service life of the project should exceed the improvement implementation cost. Potential 3R projects that are currently performing well, with relatively few crashes and little congestion, for which design improvements are considered and found to be not cost-effective, may be limited in scope to pavement resurfacing without accompanying design improvements. Making improvements that are not needed and/or not cost-effective will likely provide only small benefits and the costs may be substantial. The same funds, invested elsewhere where the need for improvement is documented and/or the cost-effectiveness of the improvement is demonstrated, would be expected to provide greater benefits, including more lives saved, more injuries prevented, and more crashes eliminated. Since available funds for 3R projects are

xii limited, highway agencies are encouraged to take a systemwide perspective in planning 3R projects, investing available funds where they will provide the greatest crash reduction and avoiding investments that will provide little crash reduction. Two spreadsheet-based benefit–cost analysis tools have been developed for use with the guidelines to implement the third bullet item listed above. Spreadsheet Tool 1 is used to assess a single design alternative (or combination of alternatives). Spreadsheet Tool 2 is used to compare multiple alternatives to identify the most cost-effective alternative (or combination of alternatives). The guidelines are presented for application by highway agencies in NCHRP Research Report 876: Guidelines for Integrating Safety and Cost-Effectivness into Resurfacing, Restoration, and Rehabilitation (3R) Projects. This report and both spreadsheet tools are available on the TRB website (trb.org); search for “NCHRP Research Report 876”. With completion of this research, the guidelines and the accompanying benefit–cost analysis tools are ready for trial application by highway agencies.