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.
TRANSPORTAT ION RESEARCH BOARD WASHINGTON, D.C. 2008 www.TRB.org N A T I O N A L C O O P E R A T I V E H I G H W A Y R E S E A R C H P R O G R A M NCHRP REPORT 612 Subject Areas Safety and Human Performance Safe and Aesthetic Design of Urban Roadside Treatments Karen K. Dixon Michael Liebler Hong Zhu OREGON STATE UNIVERSITY Corvallis, OR Michael P. Hunter Berry Mattox GEORGIA INSTITUTE OF TECHNOLOGY Atlanta, GA Research sponsored by the American Association of State Highway and Transportation Officials in cooperation with the Federal Highway Administration
NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM Systematic, well-designed research provides the most effective approach to the solution of many problems facing highway administrators and engineers. Often, highway problems are of local interest and can best be studied by highway departments individually or in cooperation with their state universities and others. However, the accelerating growth of highway transportation develops increasingly complex problems of wide interest to highway authorities. These problems are best studied through a coordinated program of cooperative research. In recognition of these needs, the highway administrators of the American Association of State Highway and Transportation Officials initiated in 1962 an objective national highway research program employing modern scientific techniques. This program is supported on a continuing basis by funds from participating member states of the Association and it receives the full cooperation and support of the Federal Highway Administration, United States Department of Transportation. The Transportation Research Board of the National Academies was requested by the Association to administer the research program because of the Boardâs recognized objectivity and understanding of modern research practices. The Board is uniquely suited for this purpose as it maintains an extensive committee structure from which authorities on any highway transportation subject may be drawn; it possesses avenues of communications and cooperation with federal, state and local governmental agencies, universities, and industry; its relationship to the National Research Council is an insurance of objectivity; it maintains a full-time research correlation staff of specialists in highway transportation matters to bring the findings of research directly to those who are in a position to use them. The program is developed on the basis of research needs identified by chief administrators of the highway and transportation departments and by committees of AASHTO. Each year, specific areas of research needs to be included in the program are proposed to the National Research Council and the Board by the American Association of State Highway and Transportation Officials. Research projects to fulfill these needs are defined by the Board, and qualified research agencies are selected from those that have submitted proposals. Administration and surveillance of research contracts are the responsibilities of the National Research Council and the Transportation Research Board. The needs for highway research are many, and the National Cooperative Highway Research Program can make significant contributions to the solution of highway transportation problems of mutual concern to many responsible groups. The program, however, is intended to complement rather than to substitute for or duplicate other highway research programs. Published reports of the NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM are available from: Transportation Research Board Business Office 500 Fifth Street, NW Washington, DC 20001 and can be ordered through the Internet at: http://www.national-academies.org/trb/bookstore Printed in the United States of America NCHRP REPORT 612 Project 16-04 ISSN 0077-5614 ISBN: 978-0-309-11753-1 Library of Congress Control Number 2008909154 © 2008 Transportation Research Board COPYRIGHT PERMISSION Authors herein are responsible for the authenticity of their materials and for obtaining written permissions from publishers or persons who own the copyright to any previously published or copyrighted material used herein. Cooperative Research Programs (CRP) grants permission to reproduce material in this publication for classroom and not-for-profit purposes. Permission is given with the understanding that none of the material will be used to imply TRB, AASHTO, FAA, FHWA, FMCSA, FTA, or Transit Development Corporation endorsement of a particular product, method, or practice. It is expected that those reproducing the material in this document for educational and not-for-profit uses will give appropriate acknowledgment of the source of any reprinted or reproduced material. For other uses of the material, request permission from CRP. NOTICE The project that is the subject of this report was a part of the National Cooperative Highway Research Program conducted by the Transportation Research Board with the approval of the Governing Board of the National Research Council. Such approval reflects the Governing Boardâs judgment that the program concerned is of national importance and appropriate with respect to both the purposes and resources of the National Research Council. The members of the technical committee selected to monitor this project and to review this report were chosen for recognized scholarly competence and with due consideration for the balance of disciplines appropriate to the project. The opinions and conclusions expressed or implied are those of the research agency that performed the research, and, while they have been accepted as appropriate by the technical committee, they are not necessarily those of the Transportation Research Board, the National Research Council, the American Association of State Highway and Transportation Officials, or the Federal Highway Administration, U.S. Department of Transportation. Each report is reviewed and accepted for publication by the technical committee according to procedures established and monitored by the Transportation Research Board Executive Committee and the Governing Board of the National Research Council. The Transportation Research Board of the National Academies, the National Research Council, the Federal Highway Administration, the American Association of State Highway and Transportation Officials, and the individual states participating in the National Cooperative Highway Research Program do not endorse products or manufacturers. Trade or manufacturersâ names appear herein solely because they are considered essential to the object of this report.
CRP STAFF FOR NCHRP REPORT 612 Christopher W. Jenks, Director, Cooperative Research Programs Crawford F. Jencks, Deputy Director, Cooperative Research Programs Charles W. Niessner, Senior Program Officer Eileen P. Delaney, Director of Publications Ellen M. Chafee, Assistant Editor NCHRP PROJECT 16-04 PANEL Field of DesignâArea of Roadside Development James Buchan, Georgia DOT, Atlanta, GA (Chair) Richard B. Albin, Washington State DOT, Olympia, WA Nancy Alexander, New York State DOT, Albany, NY Ronald K. Faller, University of NebraskaâLincoln, Lincoln, NE Mark S. Mathews, HNTB Corporation, Austin, TX Kirk G. McClelland, Maryland State Highway Administration, Baltimore, MD Keith Robinson, California DOT, Sacramento, CA Harry W. Taylor, Jr., Taylor Consulting, Washington, DC Donald Yue, STV Incorporated, New York, NY Nicholas A. Artimovich, II, FHWA Liaison Stephen F. Maher, TRB Liaison AUTHOR ACKNOWLEDGMENTS The research reported herein was performed under NCHRP Project 16â04 by the Georgia Research Institute and faculty and staff in the Department of Civil and Environmental Engineering at the Georgia Institute of Technology (Georgia Tech). The School of Civil and Construction Engineering at Oregon State University (OSU) also participated substantially in this research effort. Georgia Tech served as the pri- mary contractor for this study while OSU served as a subcontractor for the project. In addition, Glatting Jackson served as a subconsultant during the early project stages. Dr. Karen K. Dixon, P.E., Associate Professor at OSU, was the project director and co-principal inves- tigator. Dr. Michael P. Hunter, Assistant Professor at Georgia Tech, served as co-principal investigator. The other authors of this report are Michael Liebler and Hong Zhu, Graduate Research Assistants at OSU, and Berry Mattox, Graduate Research Assistant at Georgia Tech. In addition, Dr. Eric Dumbaugh of Texas A&M contributed to the literature review portion of this report. The authors would like to acknowledge agencies that provided data and case study material for this research effort. These include the cities of Phoenix, Arizona; Sacramento, California; Eden Prairie, Minnesota; Billings, Montana; Charlotte, North Carolina; Bend, Oregon; Portland, Oregon; and Salt Lake City, Utah. In addition, the Georgia Department of Transportation, the Oregon Department of Trans- portation, and the Federal Highway Administration also provided data for this project. C O O P E R A T I V E R E S E A R C H P R O G R A M S
This report presents the findings of a research project to develop recommended design guidelines for safe and aesthetic roadside treatments in urban areas and a toolbox of effec- tive roadside treatments that balance pedestrian, bicyclist, and motorist safety and mobility. The report will be of particular interest to designers and safety practitioners responsible for the design of arterial and collector-type facilities in urban areas. Many challenges are encountered when designing highway projects that pass through urban areas. Arterial and collector highways are typically designed to move vehicles as quickly and efficiently as possible. However, many times these highways are the centers of communities that have developed around them. Increasingly, citizens of these communi- ties have requested that these highways be redesigned using roadside solutions that enhance the appearance and, in many cases, the functional use of the highway. Many of the solutions involve introducing roadside treatments such as trees, sculptures, and signs. In addition to enhancing the appearance of these highways, these treatments are often also intended to slow or âcalmâ traffic to enhance safety. However, many of these treatments are considered fixed objects, as defined in the AASHTO Roadside Design Guide, and they will often be located within the design clear zone. Recommended clear zone dimensions generally represent minimum lateral offset distances. Thus, reducing existing, wider clear zones by introducing fixed objects, even at these minimum distances, reduces the recovery distance. In addition, slowing traffic may cause changes in traffic operations. Therefore, it is crucial that the impacts of these designs be understood so that decisions can be based on facts. There is also a need to identify designs that have performed acceptably and a need to develop new design guidelines that enhance the roadside environment while being forgiving to errant vehicles. Under NCHRP Project 16-04, âDesign Guidelines for Safe and Aesthetic Roadside Treat- ments in Urban Areas,â researchers at Oregon State University and the Georgia Institute of Technology developed recommended design guidelines for roadside treatments in urban areas and a toolkit that includes strategies for placing roadside objects with respect to drive- ways, intersections, merge lanes, and so forth. They also developed a draft of Chapter 10 for the AASHTO Roadside Design Guide. Two analysis approaches were used in developing the guidelines. First, a corridor assess- ment of urban roadside conditions was performed and contrasted with 6 years of historic crash data. The goal was to identify potential configurations that posed a greater risk using cluster crash analysis. By contrast, assessment of locations with similar features but without these crashes provided insight into prospective alternative treatments for roadside safety in urban environments. F O R E W O R D By Charles W. Niessner Staff Officer Transportation Research Board
In the second analysis approach, the researchers assembled case studies in which jurisdic- tions had performed roadside enhancement or âbeautificationâ projects without compan- ion major road reconstruction. A simplified before-after crash analysis, crash summaries, and project descriptive information were assembled to help determine the safety influence of the enhancement projects. The results of this case study task varied, but can be used by agencies to estimate the potential safety implications of their future roadside enhancement projects.
C O N T E N T S 1 Summary 3 Chapter 1 Background 3 Problem Statement and Research Objective 3 Scope of Study 5 Chapter 2 State-of-the-Art Summary 5 Overview of Roadside Crash Statistics 5 Roadside Safety: Current Practices 7 Examining Roadside Safety in Urban Environments 8 Preventing Vehicles from Leaving the Travelway 11 Safety of Urban Roadside Elements 36 Literature Review Conclusion 37 Chapter 3 Findings and Applications 37 Urban Control Zone Assessment 46 Case Study Task and Summary of Findings 49 General Recommendations 50 Chapter 4 Conclusions and Suggested Research 50 Conclusions 51 Suggested Research 52 References 56 Appendix A Urban Control Zone Corridor Study Reports 57 Appendix B Case Study Reports 58 Appendix C Toolkit for Urban Roadside Design 64 Appendix D Draft Chapter 10 for AASHTO Roadside Design Guide