National Academies Press: OpenBook

Communicating Changes in Horizontal Alignment (2006)

Chapter: Front Matter

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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2006. Communicating Changes in Horizontal Alignment. Washington, DC: The National Academies Press. doi: 10.17226/13938.
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T R A N S P O R T A T I O N R E S E A R C H B O A R D WASHINGTON, D.C. 2006 www.TRB.org NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM NCHRP REPORT 559 Research Sponsored by the American Association of State Highway and Transportation Officials in Cooperation with the Federal Highway Administration SUBJECT AREAS Highway Operations, Capacity, and Traffic Control Communicating Changes in Horizontal Alignment RICHARD W. LYLES AND WILLIAM C. TAYLOR Department of Civil and Environmental Engineering Michigan State University East Lansing, MI

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 Board’s 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 559 Price $30.00 Project 3-61 ISSN 0077-5614 ISBN 0-309-09851-3 Library of Congress Control Number 2006923872 © 2006 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 Board’s 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. NOTE: 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 manufacturers’ names appear herein solely because they are considered essential to the object of this report.

The National Academy of Sciences is a private, nonprofit, self-perpetuating society of distinguished schol- ars engaged in scientific and engineering research, dedicated to the furtherance of science and technology and to their use for the general welfare. On the authority of the charter granted to it by the Congress in 1863, the Academy has a mandate that requires it to advise the federal government on scientific and techni- cal matters. Dr. Ralph J. Cicerone is president of the National Academy of Sciences. The National Academy of Engineering was established in 1964, under the charter of the National Acad- emy of Sciences, as a parallel organization of outstanding engineers. It is autonomous in its administration and in the selection of its members, sharing with the National Academy of Sciences the responsibility for advising the federal government. The National Academy of Engineering also sponsors engineering programs aimed at meeting national needs, encourages education and research, and recognizes the superior achieve- ments of engineers. Dr. William A. Wulf is president of the National Academy of Engineering. The Institute of Medicine was established in 1970 by the National Academy of Sciences to secure the services of eminent members of appropriate professions in the examination of policy matters pertaining to the health of the public. The Institute acts under the responsibility given to the National Academy of Sciences by its congressional charter to be an adviser to the federal government and, on its own initiative, to identify issues of medical care, research, and education. Dr. Harvey V. Fineberg is president of the Institute of Medicine. The National Research Council was organized by the National Academy of Sciences in 1916 to associate the broad community of science and technology with the Academy’s purposes of furthering knowledge and advising the federal government. Functioning in accordance with general policies determined by the Acad- emy, the Council has become the principal operating agency of both the National Academy of Sciences and the National Academy of Engineering in providing services to the government, the public, and the scientific and engineering communities. The Council is administered jointly by both the Academies and the Institute of Medicine. Dr. Ralph J. Cicerone and Dr. William A. Wulf are chair and vice chair, respectively, of the National Research Council. The Transportation Research Board is a division of the National Research Council, which serves the National Academy of Sciences and the National Academy of Engineering. The Board’s mission is to promote innovation and progress in transportation through research. In an objective and interdisciplinary setting, the Board facilitates the sharing of information on transportation practice and policy by researchers and practitioners; stimulates research and offers research management services that promote technical excellence; provides expert advice on transportation policy and programs; and disseminates research results broadly and encourages their implementation. The Board’s varied activities annually engage more than 5,000 engineers, scientists, and other transportation researchers and practitioners from the public and private sectors and academia, all of whom contribute their expertise in the public interest. The program is supported by state transportation departments, federal agencies including the component administrations of the U.S. Department of Transportation, and other organizations and individuals interested in the development of transportation. www.TRB.org www.national-academies.org

COOPERATIVE RESEARCH PROGRAMS STAFF FOR NCHRP REPORT 559 ROBERT J. REILLY, Director, Cooperative Research Programs CRAWFORD F. JENCKS, NCHRP Manager CHARLES W. NIESSNER, Senior Program Officer EILEEN P. DELANEY, Director of Publications ANDREA BRIERE, Editor ELLEN M. CHAFEE, Assistant Editor NCHRP PROJECT 3-61 PANEL Field of Traffic—Area of Operations and Control DAVID NOYCE, University of Wisconsin—Madison (Chair) STEVEN A. MCDONALD, National Engineering Technology Corporation, Jefferson City, MO EMMANUEL OFORI-DARKO, Virginia DOT JAMES L. PLINE, Pline Engineering, Inc., Boise, ID THOMAS M. SCHRIBER, California DOT X. SAM ZHOU, New York State DOT A. J. NEDZESKY, FHWA Liaison RICHARD A. CUNARD, TRB Liaison AUTHOR ACKNOWLEDGMENTS The research reported herein was performed under NCHRP Project 3-61 by the Department of Civil and Environmental Engi- neering, Michigan State University (MSU). Portions of the project were also done under subcontract by the Department of Civil Engi- neering, North Carolina State University (NCSU). The primary investigators for this project and authors of this report are Professor Richard W. Lyles, principal investigator, and Professor William C. Taylor of MSU. Other major contributors were Fred Vanosdall, consultant, who developed and executed the driver observation study; Professor Joseph Hummer of NCSU, who was responsible for the parts of the driver surveys and practitioner focus groups done in North Carolina; Stephanie Aldighieri (formerly a graduate student at MSU and currently with the Michigan DOT), who developed and executed the driver focus groups and who was an observer in the driver observation study; John Elliott (formerly a graduate student and currently director of the Erie Redevelopment Authority in Erie, Pennsylvania), who did much of the literature review and who developed and executed the practitioner focus groups in Michigan and Indiana; and several other graduate students who were responsible for preparing materials, coding data, and analysis, but principal among them was Xinguo Jiang (Joe) and Anthony Ingle. Special recognition is also offered to Hannah Remtema, who assisted with initial work on the original project pro- posal and worked on the project for its duration (survey develop- ment and execution, data coding, data analysis, and observation in the driver study) as an undergraduate and then as a graduate student.

This report presents the findings of a research project to develop guidelines for the use of traffic control devices for communicating changes in horizontal alignment for two-lane, two-way rural roads. The report will be of particular interest to traffic engi- neering personnel with responsibility for roadway signing. Highway curves tend to be high-rate crash locations. The average crash rate for highway curves is about 3 times the average rate for highway tangents, and the average run-off-the-road crash rate for highway curves is about 4 times that of highway tangents. In lieu of curve-flattening practices or other geometrically based enhancements that are rarely employed on local road systems, traffic control devices offer the most poten- tial for reducing crash rates on horizontal curves. Warning signs (such as turn, curve, winding road, large arrow, and chevrons) with or without advisory speed plaques and a variety of delineation devices (such as wide edge lines, post delineators, raised pave- ment markers, and rumble strips) are used to communicate changes in horizontal align- ment. Nevertheless, such devices are used inconsistently from one jurisdiction to another and even from one location to another within a single jurisdiction, and they are sometimes used improperly. The devices related to horizontal alignment are rarely con- sidered as a system, but merely a collection of individual devices. Jurisdictions have varying practices regarding the spacing of delineation devices with changes in horizontal alignment; existing devices for roads with multiple changes in horizontal alignment do not provide speed information for each individual alignment change. For example, in a reverse curve with a 40-mph advisory speed, the first curve may be negotiable at 50-mph, leading to a false sense of security and a failure to slow for the second curve that has the 40-mph advisory speed or a single curve with a 30-mph advisory speed may be negotiated at 45-mph leading to distrust for advisory signing. Several recent studies have concluded that the current methodology for select- ing advisory speeds is outdated and needs to be reevaluated. Elements such as weather, roadway classification, road user familiarity, and commercial vehicle types may also affect the appropriate advisory speed Under NCHRP Project 3-61, “Communicating Changes in Horizontal Alignment,” Michigan State University researchers developed three recommendations for changes to the Manual of Uniform Traffic Control Devices. The research team reviewed the literature and ongoing research to identify design methods, practices, and problems in determining and communicating horizontal curve information to road users. Focus group exercises and interview sessions involving prac- titioners were held in Michigan, North Carolina, and Indiana. And a national survey was conducted. The objective was to determine the perceptions and actual practice of practitioners regarding traffic control devices used for horizontal curves: are they ade- quate, are they used consistently, and should guidelines for use be changed? FOREWORD By Charles W. Niessner Staff Officer Transportation Research Board

A driver behavior study using Driver Performance Monitoring (DPM) techniques was also conducted. Randomly selected drivers were observed as they traversed a 25-mile predetermined route, negotiating 43 curves. Trained observers assessed the driver’s “search, speed, and direction control” as they negotiated the curves. The vehi- cle’s speedometer readings at various points were also recorded as were comments on driving behavior. Using the information from the literature review, survey responses, input from the focus groups, and the DPM study the researchers developed several recommendations for changes to the Manual of Uniform Traffic Control Devices.

S-1 SUMMARY 1 CHAPTER 1 Introduction and Research Approach Problem Statement and Research Objective, 1 Scope of Study, 1 Research Approach, 1 Report Organization, 1 2 CHAPTER 2 Findings Literature Review, 2 Curve and Turn Signs, 2 Advisory Speeds, 2 Chevrons, 3 Edgelines and Centerlines, 3 Post-Mounted Delineators, 3 Raised Pavement Markers, 3 Discussion and Comments, 3 Practitioner Focus Groups, 4 Practitioner Survey, 6 Driver Focus Groups, 7 Crash-Involved and Typical/Average Driver Survey, 8 Field Study of Driver Behavior Using Driver Performance Monitoring Technique, 10 General DPM Route Description, 10 DPM Subjects, 10 DPM Results, 10 Discussion of DPM Results, 12 Overall Summary and Recommendations, 14 Anecdotal Observations Based on DPM Subject Performance, 15 16 CHAPTER 3 InitialGuidelines andRecommendationsfor Changes to the MUTCD Introduction, 16 Findings from this Study Related to Uniformity, 17 Recommended Changes to the MUTCD, 17 First Change, 17 Second Change, 18 Third Change, 18 Other Recommendation, 19 20 CHAPTER 4 Practitioner Opinion on Proposed MUTCD Changes Introduction, 20 Final Practitioner Survey Results, 20 First Recommendation (Changing “May” to “Should” Regarding Use of Basic Curve Signs), 20 Second Recommendation (Use of Advisory Speed Plaques), 21 Third Recommendation (Engineering Study), 21 Fourth Recommendation (Expert System), 22 26 CHAPTER 5 Revised Recommendations for the MUTCD and Related Changes Introduction, 26 First Recommendation, 26 Initial Proposed Statement, 26 Existing Statements in the MUTCD, 26 Final Proposed Statement, 26 Second Recommendation, 27 Initial Proposed Statement, 27 Existing Statements in the MUTCD, 27 Final Proposed Statement, 27 Third Recommendation, 28 Initial Proposed Statement, 28 Final Proposed Statement, 28 Fourth Recommendation, 29 Initial Proposed Statement, 29 Final Proposed Statement, 29 Concluding Remarks, 29 31 BIBLIOGRAPHY CONTENTS

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TRB's National Cooperative Highway Research Program (NCHRP) Report 559: Communicating Changes in Horizontal Alignment explores three recommended modifications to the Manual of Uniform Traffic Control Devices related to communicating changes in horizontal alignment for two-lane, two-way rural roads.

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