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2018 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 RESEARCH REPORT 869 Estimating the Safety Effects of Work Zone Characteristics and Countermeasures A Guidebook Gerald L. Ullman Michael Pratt Texas a&M TransporTaTion insTiTuTe College Station, TX Michael D. Fontaine Virginia TransporTaTion research council Charlottesville, VA Richard J. Porter VhB consulTanTs Raleigh, NC Juan Medina uniVersiTy of uTah Salt Lake City, UT Subscriber Categories Highwaysâ â¢â SafetyâandâHumanâFactors 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 is the most effective way to solve 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 results in increasingly complex problems of wide inter- est to highway authorities. These problems are best studied through a coordinated program of cooperative research. Recognizing this need, the leadership of the American Association of State Highway and Transportation Officials (AASHTO) in 1962 ini- tiated an objective national highway research program using modern scientific techniquesâthe National Cooperative Highway Research Program (NCHRP). NCHRP is supported on a continuing basis by funds from participating member states of AASHTO and receives the full cooperation and support of the Federal Highway Administration, United States Department of Transportation. The Transportation Research Board (TRB) of the National Academies of Sciences, Engineering, and Medicine was requested by AASHTO to administer the research program because of TRBâs recognized objectivity and understanding of modern research practices. TRB is uniquely suited for this purpose for many reasons: TRB maintains an extensive com- mittee structure from which authorities on any highway transportation subject may be drawn; TRB possesses avenues of communications and cooperation with federal, state, and local governmental agencies, univer- sities, and industry; TRBâs relationship to the National Academies is an insurance of objectivity; and TRB maintains a full-time staff of special- ists in highway transportation matters to bring the findings of research directly to those in a position to use them. The program is developed on the basis of research needs identified by chief administrators and other staff of the highway and transportation departments, by committees of AASHTO, and by the Federal Highway Administration. Topics of the highest merit are selected by the AASHTO Special Committee on Research and Innovation (R&I), and each year R&Iâs recommendations are proposed to the AASHTO Board of Direc- tors and the National Academies. Research projects to address these topics are defined by NCHRP, and qualified research agencies are selected from submitted proposals. Administration and surveillance of research contracts are the responsibilities of the National Academies and TRB. The needs for highway research are many, and NCHRP can make significant contributions to solving 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 research 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 by going to http://www.national-academies.org and then searching for TRB Printed in the United States of America NCHRP RESEARCH REPORT 869 Project 17-61 ISSN 2572-3766 (Print) ISSN 2572-3774 (Online) ISBN 978-0-309-44675-4 Library of Congress Control Number 2017963209 Â© 2018 National Academy of Sciences. All rights reserved. COPYRIGHT INFORMATION 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, FRA, FTA, Office of the Assistant Secretary for Research and Technology, PHMSA, or TDC 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 research report was reviewed by the technical panel and accepted for publication according to procedures established and overseen by the Transportation Research Board and approved by the National Academies of Sciences, Engineering, and Medicine. The opinions and conclusions expressed or implied in this report are those of the researchers who performed the research and are not necessarily those of the Transportation Research Board; the National Academies of Sciences, Engineering, and Medicine; or the program sponsors. The Transportation Research Board; the National Academies of Sciences, Engineering, and Medicine; and the sponsors of 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 the report.
The National Academy of Sciences was established in 1863 by an Act of Congress, signed by President Lincoln, as a private, non- governmental institution to advise the nation on issues related to science and technology. Members are elected by their peers for outstanding contributions to research. Dr. Marcia McNutt is president. The National Academy of Engineering was established in 1964 under the charter of the National Academy of Sciences to bring the practices of engineering to advising the nation. Members are elected by their peers for extraordinary contributions to engineering. Dr. C. D. Mote, Jr., is president. The National Academy of Medicine (formerly the Institute of Medicine) was established in 1970 under the charter of the National Academy of Sciences to advise the nation on medical and health issues. Members are elected by their peers for distinguished contributions to medicine and health. Dr. Victor J. Dzau is president. The three Academies work together as the National Academies of Sciences, Engineering, and Medicine to provide independent, objective analysis and advice to the nation and conduct other activities to solve complex problems and inform public policy decisions. The National Academies also encourage education and research, recognize outstanding contributions to knowledge, and increase public understanding in matters of science, engineering, and medicine. Learn more about the National Academies of Sciences, Engineering, and Medicine at www.national-academies.org. The Transportation Research Board is one of seven major programs of the National Academies of Sciences, Engineering, and Medicine. The mission of the Transportation Research Board is to increase the benefits that transportation contributes to society by providing leadership in transportation innovation and progress through research and information exchange, conducted within a setting that is objective, interdisciplinary, and multimodal. The Boardâs varied committees, task forces, and panels annually engage about 7,000 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. Learn more about the Transportation Research Board at www.TRB.org.
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 AUTHOR ACKNOWLEDGMENTS The research reported herein was performed under National Cooperative Highway Research Program (NCHRP) Project 17-61 by the Texas A&M Transportation Institute (TTI) of the Texas A&M University System, under the fiscal administration of the Texas A&M Sponsored Research Services. The Virginia Transportation Research Council (VTRC) and the University of Utah served as subcontractors for this research. Gerald L. Ullman, senior research engineer and regent fellow with TTI, was the principal investigator. The other authors of this report were Michael Pratt, assistant research engineer with TTI; Michael D. Fontaine, associate principal research scientist with VTRC; Juan Medina, research assistant professor with the University of Utah; and Richard J. Porter, highway safety engineer with VHB. The work was performed under the general supervision of Dr. Ullman. The authors also gratefully acknowledge the assistance of numerous state departments of transportation (DOT) personnel who participated in a survey of state practices. Lastly, this research could not have been completed without the special assistance of several members of the Virginia DOT, North Carolina DOT, Ohio DOT, Texas DOT, Utah DOT, and Washington State DOT who provided work zone project data for the various studies and analyses performed during the course of this research. CRP STAFF FOR NCHRP RESEARCH REPORT 869 Christopher J. Hedges, Director, Cooperative Research Programs Lori L. Sundstrom, Deputy Director, Cooperative Research Programs Waseem Dekelbab, Senior Program Officer Eileen P. Delaney, Director of Publications Kami Cabral, Editor NCHRP PROJECT 17-61 PANEL Field of TrafficâArea of Safety Theresa M. Drum, California DOT, McClellan, CA (Chair) Susan Porter, Minnesota DOT, Roseville, MN James E. Bryden, Delmar, NY Patrick A. Leonhardt, Trinity Highway, Rocklin, CA Avijit Maji, Indian Institute of Technology â Mumbai, India Steven D. Schrock, University of Kansas, Lawrence, KS Terecia W. Wilson, Institute for Global Road Safety and Security, Prosperity, SC Todd Peterson, FHWA Liaison James W. Bryant, Jr., TRB Liaison
NCHRP Research Report 869: Estimating the Safety Effects of Work Zone Characteristics and Countermeasures: A Guidebook will assist practitioners who develop phasing and staging plans for temporary traffic control through work zones in evaluating the safety impacts of their plan decisions. The material in this research report will be of immediate interest to agencies and consultants in their efforts to prepare and implement transportation manage- ment plans (TMPs) by providing a method for evaluating the potential safety benefits of certain impact mitigation countermeasures. Work zone safety is of great concern to highway agencies, the construction industry, and the traveling public. Despite this concern, there is limited data on work zone crashes and fatalities that address trends, causality, and the best use of resources to improve work zone safety. Work zone crashes can occur both inside the work space and in the traffic space. There is no single solution to creating safer work zones. Effective countermeasures depend on understanding the characteristics of crashes (types of crashes, and where and when they are occurring), the characteristics of the work zone and roadway at the time of the crash, primary and contributing factors in the crash, measures of exposure, and the frequency with which certain characteristics occur. Having a greater understanding of this information will help in more effectively targeting efforts to improve work zone safety. Clear guidance was needed to encourage the use of a data-driven, comprehensive, collaborative planning approach for the selection and implementation of effective countermeasures to improve work zone safety. Over the last decade, numerous federal, state, and local initiatives to improve highway safety have resulted in the development of national and state Strategic Highway Safety Plans (SHSP), as well as the current Toward Zero Deaths initiative. Work zone safety is a component in many statesâ SHSPs. In spite of these efforts for comprehen- sive and collaborative safety planning, many institutional barriers still remain. Under NCHRP Project 17-61, Texas A&M Transportation Institute was asked to develop comprehensive guidance on the characteristics of work zone crashes and the effectiveness of countermeasures in various categories (such as engineering, enforcement, education, emergency medical services, and public policy) to reduce work zone crash frequency and severity and improve overall work zone safety. In addition to the guidebook published as NCHRP Research Report 869, the research agencyâs final report that documents the entire research effort is available as NCHRP Web- Only Document 240: Analysis of Work Zone Crash Characteristics and Countermeasures. F O R E W O R D ByâWaseemâDekelbab StaffâOfficer TransportationâResearchâBoard
1 Chapter 1â Introduction 1 How Do Work Zones Affect Safety? 3 How to Estimate the Expected Effects of Work Zones on Crashes 3 Purpose and Organization of this Guidebook 5 Chapter 2â âPlanning-LevelâWorkâZoneâCrashâ EstimationâProcedures 5 Rationale 5 Limitations 6 Method 1: Using Pre-Work-Zone Crash Estimates and an Overall Work Zone CMF 7 Method 2: Using a Work-Zone-Based SPF 8 Examples of Computing Planning-Level Work Zone Crash Estimates 14 Chapter 3â âUsingâCMFsâtoâEvaluateâAlternativeâWorkâZoneâ DesignâFeatures,âOperatingâStrategies,â andâSafetyâCountermeasures 14 Rationale 14 Limitations 14 Method 16 Examples of Computing Crash Estimate Differences for Alternative Work Zone Design Features, Operating Strategies, and Safety Countermeasures 21 Chapter 4â CatalogâofâAvailableâWorkâZoneâCMFs 21 Overview 23 Work Zone with No Lane Closure 25 Work Zone with One or More Lanes Closed (Workers Present) 25 Work at Night (Workers Present) 26 Increase Work Zone Duration or Length 27 Use Stationary Police Enforcement 28 Use Automated Speed Enforcement 29 Use Speed Feedback Displays 30 Use Transverse Rumble Strips 32 Use Queue Warning Systems 33 Increase Inside or Outside Shoulder Width in Work Zone by 1 Ft 34 Change Median Width 36 Change Roadside Side Slope 37 Change Horizontal Curve Radius 38 Change Superelevation Variance 39 Remove Left Turn Lane 41 Remove Right Turn Lane 42 Remove Crosswalk from Minor Approaches C O N T E N T S
42 Remove Bicycle Lane 43 Remove TWLTL from Major Approach 44 Reduce Lane Width 47 Reduce Shoulder Width 48 Change Vertical Grade 49 Install Variable Speed Limit System 50 Reduce Ramp Acceleration/Deceleration Lane Length 51 Reduce Intersection Sight Distance 52 Use Crossover Work Zone (Two-Lane, Two-Way Operation) 54 Install Safety Edge on Temporary Roadway 55 Increase Retroreflectivity of Pavement Markings 56 Use Left-Hand Merge and Downstream Lane Shift (Iowa Weave) 57 Lower Posted Speed Limit 58 Install Barriers 60 Work Zone Features for Which No CMFs Exist 65â References Note: Photographs, figures, and tables in this report may have been converted from color to grayscale for printing. The electronic version of the report (posted on the web at www.trb.org) retains the color versions.