Geometric Design Practices for Resurfacing, Restoration, and Rehabilitation, National Cooperative Highway Research Program (NCHRP) Synthesis 417. A Synthesis of Highway Practice

摘要

The Resurfacing, Restoration, and Rehabilitation (3R) program began in 1976 when the U.S. Congress authorized funding for highway projects that were intended to extend the service life of an existing road. The program originally defined the 3Rs as follows: 1. ResurfacingWork to place additional layers of surfacing on highway pavement, shoulders, and bridge decks, and necessary incidental work to extend the structural integrity of these features for a substantial time period. 2. RestorationWork to return the pavement, shoulders, and bridges over a significant length of highway to an acceptable condition to ensure safety of operations for a substantial time period. 3. Rehabilitation Work to remove and replace a major structural element of the highway to an acceptable condition to extend the service life of a significant segment for a substantial period of years commensurate with the cost to construct. Over time, the desire and the requirement to make safety improvements to existing facilities in need of pavement repair changed the objective of 3R projects to include enhance safety. Subsequently, the issue became one of how much an existing roadway should be improved to achieve the safety objective. Should roads requiring pavement repair or other maintenance activities to extend their service life be brought up to full standards for geometric design or other design features. Doing so would minimize the amount of mileage that could be improved under the limited funding of the 3R program. In response to a provision in the Surface Transportation Assistance Act of 1982, TRB studied the safety and cost-effectiveness of highway geometric design standards and recommended minimum standards for 3R projects on two-lane rural highways. That study resulted in TRB Special Report 214: Designing Safer Roads: Practices for Resurfacing, Restoration, and Rehabilitation. Pursuant to its adoption of TRB SR 214, on October 17, 1988, FHWA issued Technical Advisory T5040.28, Developing Geometric Design Criteria and Processes for Non-Freeway RRR Projects. The purpose of the advisory is to provide guidance on developing or modifying criteria for the design of federal-aid, nonfreeway 3R projects. The technical advisory provides procedures, a process for developing 3R programs and projects, and design criteria for individual geometric elements. Essentially, the advisory recognized that each state could adopt its own design policy for 3R projects, but that the FHWA needed to approve state policies.