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NATIONAL
NCHRP REPORT 518
COOPERATIVE
HIGHWAY
RESEARCH
PROGRAM
Safety Evaluation of Permanent
Raised Pavement Markers
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TRANSPORTATION RESEARCH BOARD EXECUTIVE COMMITTEE 2004 (Membership as of January 2004)
OFFICERS
Chair: Michael S. Townes, President and CEO, Hampton Roads Transit, Hampton, VA
Vice Chair: Joseph H. Boardman, Commissioner, New York State DOT
Executive Director: Robert E. Skinner, Jr., Transportation Research Board
MEMBERS
MICHAEL W. BEHRENS, Executive Director, Texas DOT
SARAH C. CAMPBELL, President, TransManagement, Inc., Washington, DC
E. DEAN CARLSON, Director, Carlson Associates, Topeka, KS
JOHN L. CRAIG, Director, Nebraska Department of Roads
DOUGLAS G. DUNCAN, President and CEO, FedEx Freight, Memphis, TN
GENEVIEVE GIULIANO, Director, Metrans Transportation Center and Professor, School of Policy, Planning, and Development, USC,
Los Angeles
BERNARD S. GROSECLOSE, JR., President and CEO, South Carolina State Ports Authority
SUSAN HANSON, Landry University Professor of Geography, Graduate School of Geography, Clark University
JAMES R. HERTWIG, President, Landstar Logistics, Inc., Jacksonville, FL
HENRY L. HUNGERBEELER, Director, Missouri DOT
ADIB K. KANAFANI, Cahill Professor of Civil Engineering, University of California, Berkeley
RONALD F. KIRBY, Director of Transportation Planning, Metropolitan Washington Council of Governments
HERBERT S. LEVINSON, Principal, Herbert S. Levinson Transportation Consultant, New Haven, CT
SUE MCNEIL, Director, Urban Transportation Center and Professor, College of Urban Planning and Public Affairs, University of
Illinois, Chicago
MICHAEL D. MEYER, Professor, School of Civil and Environmental Engineering, Georgia Institute of Technology
KAM MOVASSAGHI, Secretary of Transportation, Louisiana Department of Transportation and Development
CAROL A. MURRAY, Commissioner, New Hampshire DOT
JOHN E. NJORD, Executive Director, Utah DOT
DAVID PLAVIN, President, Airports Council International, Washington, DC
JOHN REBENSDORF, Vice President, Network and Service Planning, Union Pacific Railroad Co., Omaha, NE
PHILIP A. SHUCET, Commissioner, Virginia DOT
C. MICHAEL WALTON, Ernest H. Cockrell Centennial Chair in Engineering, University of Texas, Austin
LINDA S. WATSON, General Manager, Corpus Christi Regional Transportation Authority, Corpus Christi, TX
MARION C. BLAKEY, Federal Aviation Administrator, U.S.DOT (ex officio)
SAMUEL G. BONASSO, Acting Administrator, Research and Special Programs Administration, U.S.DOT (ex officio)
REBECCA M. BREWSTER, President and COO, American Transportation Research Institute, Smyrna, GA (ex officio)
GEORGE BUGLIARELLO, Chancellor, Polytechnic University and Foreign Secretary, National Academy of Engineering (ex officio)
THOMAS H. COLLINS (Adm., U.S. Coast Guard), Commandant, U.S. Coast Guard (ex officio)
JENNIFER L. DORN, Federal Transit Administrator, U.S.DOT (ex officio)
ROBERT B. FLOWERS (Lt. Gen., U.S. Army), Chief of Engineers and Commander, U.S. Army Corps of Engineers (ex officio)
EDWARD R. HAMBERGER, President and CEO, Association of American Railroads (ex officio)
JOHN C. HORSLEY, Executive Director, American Association of State Highway and Transportation Officials (ex officio)
RICK KOWALEWSKI, Deputy Director, Bureau of Transportation Statistics, U.S.DOT (ex officio)
WILLIAM W. MILLAR, President, American Public Transportation Association (ex officio)
MARY E. PETERS, Federal Highway Administrator, U.S.DOT (ex officio)
SUZANNE RUDZINSKI, Director, Transportation and Regional Programs, U.S. Environmental Protection Agency (ex officio)
JEFFREY W. RUNGE, National Highway Traffic Safety Administrator, U.S.DOT (ex officio)
ALLAN RUTTER, Federal Railroad Administrator, U.S.DOT (ex officio)
ANNETTE M. SANDBERG, Federal Motor Carrier Safety Administrator, U.S.DOT (ex officio)
WILLIAM G. SCHUBERT, Maritime Administrator, U.S.DOT (ex officio)
ROBERT A. VENEZIA, Program Manager of Public Health Applications, National Aeronautics and Space Administration (ex officio)
NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM
Transportation Research Board Executive Committee Subcommittee for NCHRP
MICHAEL S. TOWNES, Hampton Roads Transit, Hampton, VA JOHN C. HORSLEY, American Association of State Highway
(Chair) and Transportation Officials
JOSEPH H. BOARDMAN, New York State DOT MARY E. PETERS, Federal Highway Administration
GENEVIEVE GIULIANO, University of Southern California, ROBERT E. SKINNER, JR., Transportation Research Board
Los Angeles C. MICHAEL WALTON, University of Texas, Austin
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NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM
NCHRP REPORT 518
Safety Evaluation of Permanent
Raised Pavement Markers
GENI BAHAR
CALVIN MOLLETT
iTRANS Consulting, Ltd.
Richmond Hill, Ontario, Canada
BHAGWANT PERSAUD
CRAIG LYON
Ryerson University
Toronto, Ontario, Canada
ALISON SMILEY
TOM SMAHEL
Human Factors North, Inc.
Toronto, Ontario, Canada
HUGH MCGEE
Bellomo-McGee, Inc. (BMI)
Vienna, Virginia
S UBJECT A REAS
Highway Operations, Capacity, and Traffic Control · Safety and Human Performance
Research Sponsored by the American Association of State Highway and Transportation Officials
in Cooperation with the Federal Highway Administration
TRANSPORTATION RESEARCH BOARD
WASHINGTON, D.C.
2004
www.TRB.org
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NATIONAL COOPERATIVE HIGHWAY RESEARCH NCHRP REPORT 518
PROGRAM
Systematic, well-designed research provides the most effective Project G5-17 FY'01
approach to the solution of many problems facing highway
administrators and engineers. Often, highway problems are of local ISSN 0077-5614
interest and can best be studied by highway departments ISBN 0-309-08790-2
individually or in cooperation with their state universities and
Library of Congress Control Number 2004102431
others. However, the accelerating growth of highway transportation
develops increasingly complex problems of wide interest to © 2004 Transportation Research Board
highway authorities. These problems are best studied through a
coordinated program of cooperative research. Price $20.00
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 NOTICE
Department of Transportation.
The project that is the subject of this report was a part of the National Cooperative
The Transportation Research Board of the National Academies
Highway Research Program conducted by the Transportation Research Board with the
was requested by the Association to administer the research
approval of the Governing Board of the National Research Council. Such approval
program because of the Board's recognized objectivity and reflects the Governing Board's judgment that the program concerned is of national
understanding of modern research practices. The Board is uniquely importance and appropriate with respect to both the purposes and resources of the
suited for this purpose as it maintains an extensive committee National Research Council.
structure from which authorities on any highway transportation
The members of the technical committee selected to monitor this project and to review
subject may be drawn; it possesses avenues of communications and
this report were chosen for recognized scholarly competence and with due
cooperation with federal, state and local governmental agencies, consideration for the balance of disciplines appropriate to the project. The opinions and
universities, and industry; its relationship to the National Research conclusions expressed or implied are those of the research agency that performed the
Council is an insurance of objectivity; it maintains a full-time research, and, while they have been accepted as appropriate by the technical committee,
research correlation staff of specialists in highway transportation they are not necessarily those of the Transportation Research Board, the National
matters to bring the findings of research directly to those who are in Research Council, the American Association of State Highway and Transportation
a position to use them. Officials, or the Federal Highway Administration, U.S. Department of Transportation.
The program is developed on the basis of research needs Each report is reviewed and accepted for publication by the technical committee
identified by chief administrators of the highway and transportation according to procedures established and monitored by the Transportation Research
departments and by committees of AASHTO. Each year, specific Board Executive Committee and the Governing Board of the National Research
areas of research needs to be included in the program are proposed Council.
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. Published reports of the
The needs for highway research are many, and the National
NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM
Cooperative Highway Research Program can make significant
contributions to the solution of highway transportation problems of are available from:
mutual concern to many responsible groups. The program,
however, is intended to complement rather than to substitute for or Transportation Research Board
duplicate other highway research programs. Business Office
500 Fifth Street, NW
Washington, DC 20001
and can be ordered through the Internet at:
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
http://www.national-academies.org/trb/bookstore
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. Printed in the United States of America
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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. Bruce M. Alberts 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. Bruce M. Alberts 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 4,000 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
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COOPERATIVE RESEARCH PROGRAMS STAFF FOR NCHRP REPORT 518
ROBERT J. REILLY, Director, Cooperative Research Programs
CRAWFORD F. JENCKS, NCHRP Manager
CHARLES W. NIESSNER, Senior Program Officer
EILEEN P. DELANEY, Managing Editor
BETH HATCH, Assistant Editor
ANDREA BRIERE, Associate Editor
NCHRP PROJECT G5-17 PANEL
Field of Traffic--Area of Illumination and Visibility
STEVE A. McDONALD, Missouri DOT (Chair)
THOMAS ABER, Avery Dennison, Niles, IL
LISA AULTMAN-HALL, University of Connecticut, Storrs, CT
JOHAN J. BEMELEN, Aurora, CO
LARRY CHRISTIANSON, Oregon DOT
TOM KLEMENT, Ontario Ministry of Transportation, Downsview, Ontario, Canada
DAVID C. WOODIN, New York State DOT
CARL ANDERSEN, FHWA Liaison Representative
PETER HATZI, FHWA Liaison Representative
RICHARD PAIN, TRB Liaison Representative
AUTHOR ACKNOWLEDGMENTS
The research team acknowledges and thanks the valuable assis- Pennsylvania Arthur Breneman
tance of staff from the study group states (Illinois, Missouri, New David Mallin
Jersey, New York, Pennsylvania, and Wisconsin) for their partici- Larry Hancock
pation in the data collection and for answering our numerous ques- Steve Mutchler
tions during the data management phase of the safety evaluation Neill Cheers
study. Their names are listed below: Ed Sperring
Illinois Jennifer Obertino Gaye Luddick
Bob Kleinlein Frank Cavataio
Rob Robinson George Harley
Missouri Steve A. McDonald Bill Hunter
Michael Curtit Kory Shope
New Jersey John Semler Wisconsin Richard Lange
New York Bruce Smith The research team recognizes the participation of the following
Jonathan Bray iTRANS staff members: Phoebe Fu, Kevin Shen, Joseph Palmisano,
Michael Fay Maurice Masliah, Tara Erwin, Megan Johnson, Margaret Parkhill,
Dave Clemens Michael Sone, Errol Tan, and Kenneth Ting.
Denise Sandhu
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This report presents the findings of a research project to evaluate the safety per-
FOREWORD formance of snowplowable permanent raised pavement markers (PRPMs) on two-lane
By Charles W. Niessner roadways and four-lane freeways. An analytical engineering procedure relying on
Staff Officer safety performance functions or crash prediction models for roadways with and with-
Transportation Research out PRPMs was developed to determine the potential cost-effectiveness of implement-
Board ing PRPMs at a location. The report will be of particular interest to traffic engineers
with responsibility for installing and maintaining pavement marking systems.
PRPMs were introduced for centerline and skip line application as a traffic safety
measure to provide more positive guidance for drivers in inclement weather and low-
light conditions. These devices have been popular with highway agencies and have been
widely used as supplemental delineation treatments to improve driver preview distances.
Studies in New York, Texas, and Pennsylvania have raised concerns about the rela-
tionship between PRPMs and crash rates. Specifically, the studies conducted in Texas and
Pennsylvania indicated potential negative safety effects of these devices. These studies
pertained to single jurisdictions only, and their results were questioned because of some
identified data and methodological difficulties. In general, there have been few compre-
hensive and conclusive studies performed that quantify the safety effects of PRPMs.
Under NCHRP Project 5-17, "Safety Evaluation of Permanent Raised Pavement
Markers," iTRANS Consulting, Ltd., undertook research to quantify the safety effects
of PRPMs and to develop guidelines for their use. This study gathered data in six states
(Illinois, Missouri, New Jersey, New York, Pennsylvania, and Wisconsin) to evaluate
the safety performance of snowplowable PRPMs at nonintersection locations along
two-lane roadways, four-lane expressways, and four-lane freeways.
Safety performance functions (or crash prediction models) were developed for var-
ious crash types: total, fatal and injury, nighttime, nighttime fatal and injury, daytime,
daytime fatal and injury, wet weather, dry weather, and guidance-related. These safety
performance functions (SPFs) served as a statistical tool to determine the overall effec-
tiveness of PRPMs for particular crash types at the treatment locations.
Further disaggregate analysis, using regression techniques, investigated the rela-
tionship between the effect of PRPMs on nighttime crashes and various roadway, traf-
fic, and PRPM design factors. The purpose of this disaggregate analysis was to deter-
mine some of the specific conditions under which PRPMs are effective or not in
reducing crashes. The analysis showed the following:
· The nonselective implementation of PRPMs on two-lane roadways, overall, does
not significantly reduce total or nighttime crashes, nor does it significantly
increase these crash types. At locations where PRPMs were implemented on the
basis of selective policies (i.e., poor crash history, among other criteria), the
analyses produced mixed results. Positive effects were found in New York for
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total and nighttime crashes where PRPMs were installed at locations selected on
the basis of the wet weather nighttime crash history. Similar safety effects were
not found in Pennsylvania, where PRPMs were implemented at locations
selected on the basis of total nighttime crash history. The analysis results have
also revealed that selective implementation of PRPMs requires a careful con-
sideration of traffic volumes and roadway geometry (i.e., degree of curvature).
At low volumes (annual average daily traffic [AADT] < 5,000 veh/day), PRPMs
can in fact be associated with a negative effect, which is magnified by the pres-
ence of sharp curvature. For example, for PRPMs installed on roadways with
AADTs ranging between 5,000 and 15,000 veh/day and with a degree of curva-
ture greater than 3.5, an increase of nighttime crashes of 26 percent can be esti-
mated from the model.
· Overall, the installation of PRPMs at noninterchange locations on four-lane free-
ways showed neither a positive nor a negative overall safety effect on total and
nighttime crashes. However, some significant reductions were recorded for wet
weather crashes at those locations on four-lane freeways, and there are indica-
tions that PRPMs are only effective in reducing nighttime crashes where the
AADT exceeds 20,000 veh/day.
· Because of data-intrinsic constraints, it was not viable to perform a sound safety
assessment of the effect of PRPMs on four-lane expressways.
The results obtained from the disaggregate analyses were used to develop guidelines
for the use of snowplowable PRPMs for two-lane roadways and four-lane freeways. The
guidelines are based on a two-step procedure. First, the expected safety benefit after the
installation of PRPMs is determined in relation to the expected reduction in future night-
time crashes. Second, a positive expected safety effect is followed by an analytical
engineering procedure relying on safety performance functions or crash prediction
models for roads with and without PRPMs to determine the potential cost-effectiveness
of implementing PRPMs at a location. The guidelines are discussed in the context of
the present "Manual on Uniform Traffic Control Devices" (MUTCD), and modifications
are proposed for future editions.
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CONTENTS 1 SUMMARY
3 CHAPTER 1 Introduction
4 CHAPTER 2 Review of PRPM-Related Literature and Jurisdictional Practices
2.1 Overview of PRPM Current Practices, 4
2.1.1 Nonretroreflective PRPMs, 4
2.1.2 Retroreflective PRPMs, 4
2.1.3 Implementation Criteria and Maintenance Procedures, 5
2.2 Review and Assessment of Knowledge about the Safety Effect
of PRPMs, 7
2.2.1 Review of Literature, 7
2.2.2 Methodological Problems in Past Research, 12
2.3 Literature Review of Human Factors Issues and PRPMs, 13
2.3.1 Driver Needs with Respect to Delineation and Visibility, 13
2.3.2 Visibility of PRPMs, 14
2.3.3 Driver Behavior in Response to PRPMs, 17
2.3.4 Summary, 23
24 CHAPTER 3 Data Collection and Preparation
3.1 State Survey and Selection of Potential States
for PRPM Safety Evaluation, 24
3.2 Data Collection, 25
3.2.1 PRPM Treatment Sites Inventory, 25
3.2.2 Reference and Comparison Group Sites, 26
3.2.3 Crash Data, 27
3.2.4 Roadway Attribute Data, 28
3.2.5 Traffic Volume Data, 28
3.2.6 Additional Delineation and Guidance Measures, 31
33 CHAPTER 4 Safety Impact Analysis of PRPM Installations
4.1 Composite Analysis Methodology, 33
4.2 Disaggregate Analysis Methodology, 34
4.2.1 Univariate Exploratory Analysis, 34
4.2.2 Multivariate Modeling of the Index of Effectiveness (), 34
4.3 Results of Analyses for Two-Lane Roadways, 35
4.3.1 Composite Analysis, 35
4.3.2 Univariate Disaggregate Analysis, 35
4.3.3 Multivariate Modeling of the Index of Effectiveness (site), 35
4.3.4 Spillover Analysis, 37
4.4 Results of Analysis for Four-Lane Freeways, 37
4.4.1 Composite Analysis, 37
4.4.2 Univariate Disaggregate Analysis, 39
4.4.3 Multivariate Modeling of the Index of Effectiveness (site), 39
4.5 Results of the Composite Analysis for Four-Lane Divided Expressways, 39
40 CHAPTER 5 Discussion of Study Results
5.1 Two-Lane Roadways, 40
5.1.1 Overview of Human Factors Issues, 40
5.1.2 Expected PRPM Impacts on Two-Lane Roadways, 41
5.2 Four-Lane Freeways, 42
5.2.1 Overview of Human Factors Issues, 42
5.2.2 Expected PRPM Impacts on Four-Lane Freeways, 42
44 CHAPTER 6 Guidelines for the Use of Snowplowable PRPMs
6.1 Background, 44
6.2 Proposed Guidelines for PRPMs on Two-Lane Roadways, 45
6.3 Proposed Guidelines for PRPMs on Four-Lane Freeways, 45
6.4 Proposed Revisions to the MUTCD, 45
6.5 Overview of the Analytical Engineering Procedure, 46
6.6 Illustration of the Analytical Engineering Procedure
for Two-Lane Roadways, 47
6.6.1 Step 1: Assemble Data to Use SPFs, 47
6.6.2 Step 2: Estimate Expected Nighttime Nonintersection Crashes
without PRPMs, 47
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6.6.3 Step 3: Estimate Expected Nighttime Nonintersection Crashes
with PRPMs, 48
6.6.4 Step 4: Compare Expected Crashes with and without PRPMs, 49
6.6.5 Step 5: Conduct a Benefit-Cost Analysis, 49
51 CHAPTER 7 Conclusions
53 REFERENCES
A-1 APPENDIX A Details of Calibrated Safety Performance Functions
