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

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.

3 OBJECTIVE OF SYNTHESIS The synthesis project panel provided the following charge to the consultant preparing this report: Information was to be gathered for federal-aid and non-federal-aid design prac- tices and for National Highway System (NHS) or non-NHS related to resurfacing, restoration, and rehabilitation for the following topics: • Definitions of 1R, 2R, 3R, and maintenance; • Controlling design criteria used in 3R guidelines; • Basis for development of guidelines; • To which facilities do the 3R and other standards apply (federal aid and non-federal aid); • Safety and other risk analyses used, such as Road Safety Audits; • Use of the Highway Safety Manual (HSM), Interactive Highway Safety Design Model (IHSDM), Roadside Safety Analysis Program (RSAP), or other predictive quantitative tools for 3R; • How bicycle/pedestrian/Americans with Disabilities Act (ADA) considerations are addressed in 3R; • Roadside safety design methods used in 3R; • Scope limitations [e.g., right-of-way (ROW), edge of pavement, and pavement thickness] and what is or is not included; and • Need for improved or updated guidance and future research. As with most NCHRP synthesis projects, information to address these issues was gathered through a literature review, survey of transportation agencies, and selected interviews. CONTENTS OF SYNTHESIS Following this introduction, there are four chapters. Chapter two provides a chronology of the development of 3R design guidelines. Chapter three presents the results of a survey questionnaire sent to all states. Chapter four discusses how a sample of states deal with the various geometric design criteria as presented in their 3R policy documents. Chap- ter five provides a summary of major findings and recom- mendations for further research. Several appendixes provide supporting material. CHAPTER ONE INTRODUCTION BACKGROUND The Resurfacing, Restoration, and Rehabilitation (3R) pro- gram began in 1976 when Congress authorized funding for highway projects that were intended to extend the service life of an existing road. Over time, the desire and the require- ment to make safety improvements to an existing facility in need of pavement repair changed the objective of 3R projects to include “enhance safety.” In response to a provision in the Surface Transportation Assistance Act of 1982, TRB stud- ied 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 (SR) 214: Designing Safer Roads: Practices for Resurfacing, Restoration, and Rehabilitation (1). AASHTO subsequently amended the foreword of the Policy on Geometric Design for Highways and Streets (2) to include the following sentence: “This publication is not intended as a policy for Resurfacing, Restoration, or Reha- bilitation (3R) projects and refers the reader to TRB Special Report 214 for design guidance.” In 2001, AASHTO pub- lished Guidelines for Geometric Design for Very-Low Vol- ume Local Roads (ADT ≤ 400) (3). This document does not specifically address 3R work, but it does provide some guid- ance related to improving the safety and cost-effectiveness of geometric design for existing, low-volume roads. Although TRB SR 214 specifically addresses 3R work on rural two-lane highways and AASHTO provides limited guidance on roads with an average daily traffic (ADT) of fewer than 400 vehicles per day, there is a lack of design guidance for 3R work on a wide range of roads, including urban nonfreeway facilities and rural multilane nonfreeway facilities. A need exists to document the state of highway practice related to 3R design guidelines for all nonfreeway roadway types. Most state transportation agencies have 3R design guidelines, but these differ greatly in scope and con- tent, and as a result the range of current practice is consid- erable. Therefore, the main focus of this synthesis project was to gather and synthesize current practices related to 3R design. It is believed that such an effort will be of consider- able value to transportation agencies preparing newly devel- oped or revised guidelines for 3R projects. Although each state tailors design policies to its specific conditions, there are many commonalities with regard to geometric design and how these features affect safety.