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

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4 CHAPTER TWO HISTORY AND CURRENT STATUS OF DESIGN GUIDELINES FOR RESURFACING, RESTORATION, AND REHABILITATION PROJECTS EVOLUTION OF THE RESURFACING, RESTORATION, AND REHABILITATION PROGRAM The program of resurfacing, restoration, and rehabilita- tion, also known as 3R, emerged out of the 1976 Federal- Aid Highway Act (P.L. 94-280). Prior to that legislation, federal funding had been limited to constructing new roads or reconstructing existing roads to higher design standards. State and local agencies used their own transportation rev- enues to fund maintenance and preservation of roads that had approached the end of their design life. The Federal- Aid Highway Act amended the U.S. Code to include the 3Rs within the definition of construction. The legislation permit- ted the use of federal aid to rehabilitate highways to extend their useful life without necessarily improving existing geo- metrics. These projects were not required to comply with the then-current design standards, and typically would not change existing design dimensions. The 3Rs were defined as follows: • Resurfacing – Work to place additional layers of sur- facing on highway pavement, shoulders, and bridge decks, and necessary incidental work to extend the structural integrity of these features for a substantial time period. • 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. This work may include the following: grinding and repair of joints of portland cement concrete pavement, sealing of shoulders and pavement joints in conjunction with other work, place- ment of a skid resistant surface treatment, correction of minor drainage conditions, and work to prepare a bridge deck for an overlay. • Rehabilitation – Work to remove and replace a major structural element of the highway to an acceptable con- dition to extend the service life of a significant segment for a substantial period of years commensurate with the cost to construct. This work may include the following: replacement of bridge deck, pavement, or shoulders without significant widening; recycling of pavement and shoulder materials: replacement of the individual bridge elements to correct a structural deficiency; and minor subgrade work incidental to other work. In 1977, AASHTO published Geometric Design Guide for Resurfacing, Restoration, and Rehabilitation (R-R-R) of Highways and Streets (4) (also known as the Purple Book) to provide guidance to the states on the types of 3R projects, geometric guidelines, and design elements. The guide stated that the primary purpose of 3R projects was to “provide bet- ter riding surface, increase safety, and improve operating conditions, to the most feasible degree.” It recognized that to stretch limited highway resources, flexibility in standards for improvements was essential. Design guidelines were pro- vided for the following elements: • Speed; • Pavement (lane) and shoulder width; • Superelevation; • Grades, curvature, and stopping sight distance; • Bridge structural capacity and width; • Horizontal clearance to obstructions; • Drainage; • Curbing and channelization; • Sidewalks; • Bikeways; • Utilities; • Lighting; • Aesthetics and landscaping; and • Railroad crossings at grade. FHWA did not accept the Purple Book for nationwide use, and it is no longer published by AASHTO. Instead, FHWA decided to develop its own geometric design cri- teria for federal-aid nonfreeway 3R projects. In 1978, an FHWA-developed guide was published as a notice of pro- posed rulemaking. The guide provided definitions and specific geometric criteria for various roadway design ele- ments. The hallmark of the proposed guide was to provide minimums, but encouraged higher values where possible and practical. It provided flexibility in design that would allow for cost-effective improvements to safety without requiring total reconstruction. However, it was criticized by safety advocates who believed that safety would be com- promised because only minimums would be followed. This criticism prompted more study by FHWA, which led to the technical report RRR Alternative Evaluations for Non- Interstate Rural Arterial and Collector Highway Systems (5). The report concluded that greater overall system safety

5 could be achieved by improving more miles with less costly improvements than fewer miles of full construction. This premise continues to be one of the key issues surrounding the 3R program—just how much should be invested for safety improvements for any given 3R project, which will then limit the amount available for other projects within a fiscal year. On June 10, 1982, FHWA issued its final rule, entitled Design Standards for Highways: Resurfacing, Restoration, and Rehabilitation of Streets and Highways Other Than Freeways (6). This final rule modified 23 CFR Part 625 to adopt a flexible approach to the geometric design of 3R projects. Part 625 was modified again on March 31, 1983, to explicitly state that one objective of 3R projects is to enhance highway safety. In the final rule, FHWA determined that it was not practical to adopt 3R design criteria for nationwide application; instead, each state can develop its own criteria and procedures for 3R projects, subject to FHWA approval. This allows each state to tailor its design criteria for the 3R program according to prevailing conditions. This approach is in contrast to the application of criteria for new construc- tion and major reconstruction, for which AASHTO’s A Policy on Geometric Design of Highways and Streets (7) provides nationwide criteria for application. FHWA subsequently issued Technical Advisory T 5040.21, Geometric Design Criteria for Nonfreeway RRR Projects, in 1983 (8). It provided guidance relating to 11 fac- tors to be addressed, as a minimum, in the geometric design criteria developed by a state for use on 3R projects. In 1985, 23 CFR 625 was revised to adopt AASHTO’s A Policy on Geometric Design of Highway and Streets. In the implementing memorandum of April 15, 1985, FHWA identified the following 13 controlling criteria: 1. Design speed 2. Lane width 3. Shoulder width 4. Bridge width 5. Structural capacity 6. Horizontal alignment 7. Vertical alignment 8. Stopping sight distance 9. Grades 10. Cross-slopes 11. Superelevation 12. Horizontal clearance 13. Vertical clearance. Deviations from these criteria required a formal design exception. The 13 controlling criteria were relevant to new and reconstruction projects, but they were embraced later for 3R guidelines. In response to a provision of the 1982 Surface Transporta- tion Assistance Act, the National Academy of Sciences was requested to study the safety cost-effectiveness of geometric design standards and recommend minimum standards for 3R projects on existing nonfreeway federal-aid highways. This study led to TRB SR 214: Designing Safer Roads, Practices for Resurfacing, Restoration, and Rehabilitation, published in 1987 (1). Part 625 was again revised to add this report as a guide and reference to the list of publications for application on federal-aid projects. The report— 1. Reviewed the existing 3R design practices of 15 state departments of transportation (DOTs) and several local highway agencies. 2. Examined the relationship between highway accident potential and geometric design elements, based on existing research literature and on special research projects commissioned as part of the study. 3. Examined the relationship between the extent of geometric design improvements and the cost of 3R projects. 4. Discussed the issue of cost-effectiveness relative to geometric design improvements on 3R projects. 5. Reviewed the literature on tort liability and geometric design. 6. Presented a safety-conscious design process. 7. Presented specific numerical criteria for the geomet- ric design of 3R projects for the following elements: • Lane and shoulder width • Horizontal curvature and superelevation • Vertical curvature • Bridge width • Side slopes • Pavement cross slope Pursuant to its adoption of TRB SR 214, on October 17, 1988, FHWA issued Technical Advisory T5040.28, Devel- oping Geometric Design Criteria and Processes for Non-

6 Freeway RRR Projects (9). The purpose of the advisory is to provide guidance on developing or modifying criteria for the design of federal-aid, nonfreeway 3R projects. The tech- nical advisory— 1. Discusses the procedures for developing 3R criteria. 2. Discusses the factors that should be evaluated in a safety-conscious design process. 3. Discusses the application of design exceptions for the FHWA controlling design criteria on 3R projects. 4. Presents specific criteria for the design of 3R projects based on TRB SR 214. The full document is provided as Appendix A; the high- lights are discussed here. The advisory provides procedures, a process for develop- ing 3R programs and projects, and design criteria for indi- vidual geometric elements. Under Procedures, it states that “each State may choose one or a combination of the follow- ing options: (1) develop and adopt geometric design criteria specifi- cally for nonfreeway 3R projects, (2) adopt and apply current geometric design crite- ria for new construction (referenced in 23 CFR 625.4(a)(1) to nonfreeway 3R projects , and/or (3) continue to use previously approved geometric design criteria for nonfreeway 3R projects that have been in existing Certification Acceptance or Secondary Road Plan agreements, provided such criteria are consistent with 23 U.S.C. 109 (o).” The advisory recognizes TRB SR 214 as having “the most current source of data, procedures and recommendations regarding geometric design and its relationship to safety for 3R projects, and that it can be used to develop or modify cri- teria, processes and practices to achieve the twin objectives of 3R type projects—preservation and safety enhancement.” It also states that the states’ 3R design criteria should address all 13 controlling geometric elements mentioned previously and includes recommendations from TRB SR 214 on lane and shoulder widths and bridge widths. In addition, guid- ance is provided on other design features, including pave- ment improvements, skid-resistant surfaces and pavement edge drop-off remediation; intersection improvements; and traffic controls and regulations. CURRENT DESIGN POLICIES AND GUIDELINES APPLICABLE TO RESURFACING, RESTORATION, AND REHABILITATION PROJECTS Currently, there are no national design guidelines for 3R projects. States can develop their own standards for these projects, and in doing so they have drawn from various design guideline documents, including the following docu- ments from AASHTO, FHWA, and TRB SR 214. AASHTO Design Guides Most highway design guidelines followed by state DOTs are developed and published by AASHTO. The AASHTO Standing Committee on Highways is charged with develop- ing these guides using subcommittees and assigned techni- cal committees. The following AASHTO guides contain information on 3R design guidelines. • A Policy on Geometric Design of Highways and Streets (7)—Known as the Green Book, this document pro- vides guidelines for all road type designs, applicable to new and reconstructed roads. The foreword contains the following statement on 3R projects: This publication is not intended as a policy for 3R projects. For projects of this type, where major revisions to horizontal or vertical curvature are not necessary or practical, existing design values may be retained. Specific site investigations and crash history analysis often indicate that the existing design features are performing in a satisfactory manner. The cost of full reconstruction for these facilities, particularly where major realignment is not needed, will often not be justified. 3R projects enable highway agencies to improve highway safety by selectively upgrading existing highway and roadside features without the cost of full reconstruction. When designing 3R projects, the designer should refer to TRB Special Report 214, Designing Safer Roads: Practices for Resurfacing, Restoration, and Rehabilitation and related publications for guidance. • Guidelines for Geometric Design of Very Low-Volume Local Roads (ADT ≤ 400), 2001 (3)—This design pol- icy was prepared to address the needs of functionally classified local roads with average daily traffic volumes of up to 400 cars. Because these roads typically have low frequency of crashes and primarily serve drivers who are familiar with the roadway, it was believed that designers could apply less restrictive design cri- teria than those used for higher volume roads, and for which the Green Book would apply. This guide applies to both new construction and the improvement of exist- ing roads, and its application to 3R projects is noted in the following statement:

7 Safety-Conscious Design Process 1. Assessment of Site Conditions Affecting Safety 2. Determination of Project Scope 3. Documentation of the Design Process 4. Review by Traffic and Safety Engineers Design Practices for Key Highway Features 5. Minimum Lane and Shoulder Widths 6, 7. Horizontal Curvature and Superelevation 8. Vertical Curvature and Stopping Sight Distance 9. Bridge Width 10. Sideslopes and Clear Zones 11. Pavement Edge Drop and Shoulder Type 12. Intersections 13. Normal Pavement Crown Other Design Procedures and Assumptions 14. Traffic Volume Estimates for Evaluating Geometric Improvements 15. Speed Estimates for Evaluating Geometric Improve- ments 16. Design Values for Geometric Improvements 17. Design Exceptions Planning and Programming RRR Projects 18. Screening of Highways Programmed for RRR projects 19. Assessment of the Systemwide Potential for Improv- ing Safety Safety Research and Training 20. Special Task Force to Assess Highway Safety Needs and Priorities 21. Compendium of Information on Safety Effects of Design Improvements Projects on existing very low-volume local roads may involve reconstruction, resurfacing, rehabilitation, restoration and other improvements. Changes to roadway or roadside geometrics during such projects are generally recommended only where there is a documentable site- specific safety problem that can potentially be corrected by a roadway or road side improvement. In general, the guidelines discourage widening of lanes and shoulders, changes in horizontal and vertical alignment, and roadside improvements, except in situations where such improvements are likely to provide substantial safety benefits. • Roadside Design Guide (RDG) (10)—This document presents a synthesis of current information and operat- ing practices related to roadside safety. The roadside is defined as that area beyond the traveled way (driving lanes) and the shoulder (if any) of the roadway. The focus of the guide is on safety treatments that mini- mize the likelihood of serious injuries when a driver runs off the road. Its guidelines are most applicable to new construction or major reconstruction projects. The RDG recognizes that the primary emphasis of 3R projects is generally placed on the roadway and that it is necessary to selectively incorporate roadside safety guidelines at locations where the greatest safety ben- efit can be realized. The RDG contains guidelines for one of the 13 controlling design elements—horizon- tal clearance (other than Clear Zone). However, the RDG discusses many roadside features that may be improved and upgraded during 3R projects, including the following: − Side slopes—foreslopes and backslopes; − Drainage features; − Curbs; − Sign, traffic signal, and luminare supports; − Roadside barriers; − Bridge railings; and − Barrier end treatments and crash cushions. FHWA Guidance Current FHWA guidance on geometric design criteria is found in aforementioned FHWA Technical Advisory T 5040.28, Developing Geometric Design Criteria and Pro- cess for Nonfreeway RRR Projects (9), which can be found in Appendix A. Transportation Research Board Special Report 214 TRB SR 214, published in 1987, offered 23 recommendations for 3R projects with the objective of improving safety in a cost-effective manner. The following is a list of the recom- mendations, grouped into five major categories:

8 22. Increased Research on the Relationships Between Safety and Design 23. Safety Training Activities for Design Engineers TRB SR 214 contains a complete discussion of these rec- ommendations. It can be accessed at www.trb.org/publica- tions/sr/sr214/sr214_001_fm.pdf. Appendix B contains a summary of the recommendations that pertain to the geo- metric design elements discussed in this synthesis. The information presented in this chapter lays the foun- dation for the remainder of this synthesis. States were given the flexibility to develop their own design policies for 3R projects, and have used the aforementioned AASHTO poli- cies, the FHWA technical advisory, TRB SR 214, and other documents in developing geometric design policy appro- priate to their conditions and design procedures. The next chapter describes how states have developed their 3R poli- cies and provides the responses to the questionnaire sent to the states.