NCHRP Report 876, Guidelines for Integrating Safety and Cost-Effectiveness into Resurfacing, Restoration, and Rehabilitation (3R) Projects,
presents a rational approach for estimating the cost-effectiveness of including safety and operational improvements in a resurfacing, restoration, or rehabilitation (3R) project. The approach uses the performance of the existing road in estimating the benefits and cost-effectiveness of proposed design improvements. These guidelines are intended to replace TRB Special Report 214, Designing Safer Roads: Practices for Resurfacing, Restoration, and Rehabilitation.
The guidelines are accompanied by two spreadsheet tools, one for analyzing a single design alternative and one for comparing several alternatives or combinations of alternatives (available at the link above).
Prior to 1976, federal highway funds could only be used for the construction of new highways or the reconstruction of existing highways. The Federal-Aid Highway Act of 1976 allowed the use of federal aid for resurfacing, restoration, and rehabilitation (3R) projects on federal-aid highways. However, in 1976 there were no standards for 3R improvements. Transportation agencies relied on standards for new or reconstructed roadways in the AASHTO Policy on Geometric Design of Highways and Streets (the “Green Book”), and where the proposed geometric elements did not meet the AASHTO guidelines on a 3R project, design exceptions or exemptions had to be sought. In response to a provision in the Surface Transportation Assistance Act of 1982, the Secretary of Transportation requested the National Academy of Sciences (now the National Academies of Sciences, Engineering, and Medicine) to study the cost-effectiveness of geometric design standards and recommend minimum standards for 3R projects on existing federal-aid highways, except freeways. The purpose of 3R standards was two-fold: (1) to identify minimum standards for selective geometric elements for which 3R funding could be used to maintain existing highways in an effort to extend their service life and (2) to provide transportation agencies with the ability to make cost-effective improvements to existing highways for selective geometric elements to enhance safety and reduce crashes. The result of this study was TRB Special Report 214: Designing Safer Roads: Practices for Resurfacing, Restoration, and Rehabilitation published in 1987.
Since 1987, values for many of the design elements within the AASHTO Green Book have been revised, including FHWA’s designated 13 controlling criteria, and the cost of construction has changed. Incremental geometric design improvements in 3R projects can be cost effective and have significant payoffs in safety and operational benefits. Furthermore, with the publication of the AASHTO Highway Safety Manual and other recent publications, additional knowledge is available regarding the relationship of geometric elements to the frequency and severity of crashes.
In NCHRP Project 15-50, MRIGlobal reviewed the literature and state of the practice for designing 3R projects. They also reviewed the latest research on the safety impacts of design improvements and developed cost-benefit analysis equations for the most common design improvements applied to 3R projects. This was supported by the development of spreadsheet tools for evaluating alternative designs. The final research results reflect the experience of 6 state departments of transportation in applying the draft design guidelines and supporting materials. This occurred under NCHRP Project 15-50(01), “Implementation Assessment of 3R Design Guidelines.”