Geometric Design Practices for Resurfacing, Restoration, and Rehabilitation (2011)

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SUMMARY GEOMETRIC DESIGN PRACTICES FOR RESURFACING, RESTORATION, AND REHABILITATION 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. Resurfacing—Work 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. Restoration—Work 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 high- way 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 facil- ities 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 geo- metric 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 rec- ommended 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 pro- grams 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. Owing to the state-to-state variations in standards and guidelines for 3R projects, more information is needed on the current state of highway practice related to 3R design guide- lines for all nonfreeway roadway types. Therefore, the main focus of this synthesis project was to gather and synthesize current practices related to 3R geometric design. The infor- mation presented in the synthesis is derived from the following sources:

2 1. A 15-question survey distributed to all state transportation agencies, 2. A compilation and review of the state design manuals that contained 3R policies, and 3. A focused literature review. All but two states responded to the survey. According to the survey responses— • All but eight states responding have an FHWA-approved 3R policy; the others have a program that has similar objectives. • Most 3R projects are initiated because of the condition of the pavement, but then are reviewed to determine what safety enhancements are justified. • The safety analyses typically include a review of crash history to see if a “crash prob- lem” exists. However, some states are incorporating new safety tools and methods to include road safety audits/assessments and the application of safety models found in the new Highway Safety Manual. • Design speed, lane width, and shoulder width are considered the most important design elements of the 13 controlling design criteria. • The most frequent safety improvements are those related to the roadside, including increasing the clear zone and upgrading barriers and other roadside safety devices. • Many states are including improvements for pedestrians and bicyclists within the con- straints of 3R projects and are providing required Americans with Disabilities Act improvements such as accessible curb ramps and walkway slopes. • There is wide state-by-state variation in the time it takes to have a 3R project imple- mented after the need has been identified and in the number of 3R projects completed each year. • Many states expressed a need to improve 3R guidelines to include a process for deter- mining how many safety upgrades should be made, given restricted budgets. For nearly all states, the documents that provide their 3R policies were obtained from their website or directly provided by the state, and can be accessed at http://www.trb.org/ SynthesisPrograms/Public/CompilationofStateDesignManuals.aspx. A review of these documents confirmed the variation in the scope and content of the states’ policies. They range from fairly concise documents of about 10 pages to much more comprehensive, lengthy documents, with the longest single document being 92 pages. Most states include the 13 controlling critical design elements determined by FWHA, for which design exceptions should be prepared if not within minimum values. However, many states go beyond these criteria and provide guidance on other features, including intersections, clear zone, roadside features, drainage, traffic control devices, driveways, lighting, and even landscaping. The report provides a discussion of how states treat these design elements for 3R projects. The synthesis concludes with a summary of key findings and a recommendation for two general research efforts: to expand our knowledge of the relationship of design elements to safety and to continue to develop and improve upon crash modification factors for various safety improvements.