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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 893 Systemic Pedestrian Safety Analysis Libby Thomas Laura Sandt Charles Zegeer Wesley Kumfer Katy Lang Bo Lan HigHway Safety ReSeaRcH centeR UniveRSity of noRtH caRolinaâcHapel Hill Chapel Hill, NC a n d Zachary Horowitz Andrew Butsick Joseph Toole KittelSon & aSSociateS, inc. Portland, OR a n d Robert J. Schneider UniveRSity of wiSconSinâMilwaUKee, conSUltant Milwaukee, WI Subscriber Categories Pedestrians and Bicyclists â¢ Planning and Forecasting â¢ Safety and Human Factors 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 893 Project 17-73 ISSN 2572-3766 (Print) ISSN 2572-3774 (Online) ISBN 978-0-309-47985-1 Library of Congress Control Number 2018957142 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 authors acknowledge the significant contributions of the research panel and the agencies and their staffs that contributed case examples and insights that enhanced this projectâs report and guide- book. The authors gratefully acknowledge the Seattle Department of Transportation and the Toole Design Group for the use of data developed for the 2016 City of Seattle Bicycle and Pedestrian Safety Analysis project. The authors also acknowledge Seattle Department of Transportation staff, who assisted with informa- tion for Case Example 1, and Caltrans staff, who assisted with information for Case Example 4. Katy Lang is now a program manager for WalkArlington in Virginia. CRP STAFF FOR NCHRP RESEARCH REPORT 893 Christopher J. Hedges, Director, Cooperative Research Programs Lori L. Sundstrom, Deputy Director, Cooperative Research Programs Ann Hartell, Senior Program Officer Jarrel McAfee, Senior Program Assistant Eileen P. Delaney, Director of Publications Natalie Barnes, Associate Director of Publications Linda A. Dziobek, Senior Editor NCHRP PROJECT 17-73 PANEL Field of TrafficâSafety Darren V. McDaniel, Texas DOT, Austin (Chair) Kevin S. Murphy, Delaware Valley Regional Planning Commission, Philadelphia, PA Robert M. Nelson, Illinois DOT, Paris Bonnie S. Polin, Massachusetts Department of Transportation, Newton James B. âByronâ Rushing, Atlanta Regional Commission, GA Amanda Westmoreland Salyer, Oregon DOT, Salem William âJarrodâ Stanley, Kentucky Transportation Cabinet, Frankfort Keith Sinclair, FHWA Liaison Kelly K. Hardy, AASHTO Liaison Bernardo Kleiner, TRB Liaison
NCHRP Research Report 893: Systemic Pedestrian Safety Analysis provides a safety analy- sis method that can be used to proactively identify sites for potential safety improvements based on specific risk factors for pedestrians. A systemic approach, as opposed to a âhot spotâ approach, enables transportation agencies to identify, prioritize, and select appro- priate countermeasures for locations with a high risk of pedestrian-related crashes, even when crash occurrence data are sparse. The guidebook will be of interest to transportation agency staff responsible for safety improvement programs, pedestrian planning, and pri- oritization of projects. The guidebook also provides important insights for the improve- ment of data collection and data management to better support systemic safety analyses. Pedestrian-related crashes accounted for approximately 12% of all traffic fatalities in the United States, amounting to more than 49,000 deaths during the last decade. Data from 2016 and 2017 show continued increases in pedestrian crashes and fatalitiesâa troubling trend. Improving the design and operation of the transportation system in part may reduce crashes and fatalities among these vulnerable road users. For agencies to make effective safety improvements, they must understand what risk factors are associated with pedestrian-related crashes, where those risks exist on the transportation network, and what countermeasures can be implemented at those locations to mitigate the risks. Unlike the more traditional site analysis approach, which identifies locations where collisions have been concentrated in the past, the systemic approach pro actively identifies sites based on specific risk factors known to be associated with a particular crash type or grouping of crash types. These sites may be spread across the network and may include locations with no history of high crash volumes. Focusing on crash risk rather than on crash history allows agencies to prioritize improvements that can prevent crashes, supporting a comprehensive yet cost-effective safety program by targeting improvements to the highest risk locations. Understanding risk factors also helps in the selection of countermeasures that are appropriate for addressing the risks at a particular site. This guidebook was developed by a consultant team led by the Highway Safety Research Center at the University of North CarolinaâChapel Hill in partnership with Kittelson & Associates, Inc., and Robert J. Schneider. The guidance is based on research that used data on roadway characteristics, pedestrian crashes, and measures of exposure to develop new risk factors for pedestrian-related crashes. A set of countermeasures known to improve pedestrian safety was compiled, and a method was developed to use the risk factors to iden- tify appropriate countermeasures for locations with high crash potential. F O R E W O R D By Ann Hartell Staff Officer Transportation Research Board
The results of the research provide the basis for the guidance in NCHRP Research Report 893. The guidebook is a practitioner-ready resource to implement the research results with step-by-step guidance on how to conduct a systemic pedestrian safety analysis, along with four case studies highlighting early applications of systemic approaches to pedestrian safety analysis. A technical report documenting the research and a summary presentation of the project are available from TRBâs website (www.trb.org) by searching for NCHRP Research Report 893.
1 Summary 3 Chapter 1 Introduction to Purpose and Process of Systemic Analysis 3 Essentials of a Systemic Approach 3 Motivation for a Systemic Approach 6 Steps in a Systemic Pedestrian Safety Analysis Process 8 Chapter 2 Step 1: Define Study Scope 8 Identify Network for Analysis 9 Identify One or More Target Locations and Crash Types 14 Finalize Area and Location Type Scope 14 Additional Resources 15 Chapter 3 Step 2: Compile Data 15 Compile Roadway Data for Focus Facility Type 20 Add Other Pedestrian Crash Exposure Measures to Facility Data 23 Count Target Crash Types by Location and Add to Database 24 Additional Resources 25 Chapter 4 Step 3: Determine Risk Factors 25 Select Approach to Determine Risk Factors 32 Perform Analyses and Identify Risk Factors 34 Additional Resources 35 Chapter 5 Step 4: Identify Potential Treatment Sites 35 Consider Eliminating Low Crash Potential Sites 35 Generate Initial List of Sites 38 Additional Resources 39 Chapter 6 Step 5: Select Potential Countermeasures 39 Establish a Framework for Selecting Countermeasures 40 Develop an Initial List of Potential Systemic Countermeasures 41 Select Countermeasures 46 Additional Resources 47 Chapter 7 Step 6: Refine and Implement Treatment Plan 47 Consider Additional Community Priorities 48 Perform Additional Diagnostics 48 Perform Economic Assessments 52 Allocate Funding 53 Additional Resources 54 Chapter 8 Step 7: Evaluate Program and Project Impacts 54 Evaluate Systemic Programs 55 Evaluate Systemic Projects C O N T E N T S
55 Renew Analyses 56 Additional Resources 57 Chapter 9 Case Example 1: Seattle Department of Transportation 57 Background and Motivation 57 Step 1: Define Study Scope 58 Step 2: Compile Data 59 Step 3: Determine Risk Factors 59 Step 4: Identify Potential Treatment Sites 60 Other Steps and Lessons Learned to Date 62 Chapter 10 Case Example 2: Oregon Department of Transportation 62 Background and Motivation 63 Step 1: Define Study Scope 63 Step 2: Compile Data 63 Step 3: Determine Risk Factors 64 Step 4: Identify Potential Treatment Sites 64 Step 5: Select Potential Countermeasures 64 Step 6: Refine and Implement Treatment Plan 65 Other Steps and Lessons Learned to Date 66 Chapter 11 Case Example 3: Arizona Department of Transportation 66 Background and Motivation 66 Step 1: Define Study Scope 66 Step 2: Compile Data 67 Step 3: Determine Risk Factors 68 Step 4: Identify Potential Treatment Sites 69 Step 5: Select Potential Countermeasures 69 Step 6: Refine and Implement Treatment Plan 69 Other Steps and Lessons Learned to Date 71 Chapter 12 Case Example 4: California Department of Transportation 71 Background and Motivation 71 Step 1: Define Study Scope 71 Step 2: Compile Data 72 Step 3: Determine Risk Factors 72 Step 4: Identify Potential Treatment Sites 72 Step 5: Select Potential Countermeasures 73 Other Steps and Lessons Learned to Date 74 Chapter 13 Conclusion: Considerations and Limitations 75 Continuing Research Needs 75 Implementation 76 References 80 Appendix Potential Countermeasures 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.
AADP Average Annual Daily Pedestrian AADT Average Annual Daily Traffic (Motor Vehicles) AASHTO American Association of State Highway and Transportation Officials ADT Average Daily Traffic Caltrans California Department of Transportation CEI Cost-Effectiveness Index; see also Glossary CMF Crash Modification Factor; see also Glossary HAWK High-intensity Activated crossWalK HSIP Highway Safety Improvement Program (or Plan) HSM Highway Safety Manual LPI Leading Pedestrian Interval MPH Miles Per Hour MUTCD Manual on Uniform Traffic Control Devices PBCAT Pedestrian and Bicycle Crash Analysis Tool PEDSAFE Pedestrian Safety Guide and Countermeasure Selection System PEDSMARTS Pedestrian Systemic Monitoring Approach for Road Traffic Safety PHB Pedestrian Hybrid Beacon SPF Safety Performance Function (i.e., crash prediction model); see also Glossary TWLTL Two-Way Left-Turn Lane A C R O N Y M S
The glossary provides definitions of key terms within the context of this guidebook. Other references or agencies may have different definitions and uses for these terms. Cost-Effectiveness IndexâEstimates the cost to reduce one vehicleâpedestrian crash. It is calculated by dividing project costs by the expected reduction in pedestrian crashes. See Step 6 for details. Crash FrequencyâNumber of crashes at a defined location over a defined time period. Crash Modification FactorâA numerical estimate of the expected reduction (or increase) in the number of crashes that may result when a countermeasure treatment is implemented. Crash TypeâA variable that typically describes events and maneuvers of the involved parties that led up to a crash. The relative maneuvers of the parties such as road departure (single vehicle), angle crash (between two motor vehicles), or pedestrian crossing at midblock and struck by a vehicle traveling straight (pedestrianâmotor vehicle crash type) are examples. Crash PredictorâAny characteristic of the roadway, environment, vehicle, or popula- tion attribute that helps to predict future crashes based on a quantified association with prior crashes (such as in a safety performance function or SPF, see definition below). In other words, these are measured variables associated with crash frequencies and used to estimate risk (see definition below). Crash predictors themselves may not have a causal relation or theoretical basis for increasing risk, but they may serve as surrogate measures for certain risk factors (see definitions of these terms below). NetworkâThe complete network of streets within a defined area or jurisdiction. Pedestrian ExposureâUsing the Safe States Alliance Consensus Recommendations for Pedestrian Injury Surveillance definition, pedestrian exposure is âan observable period or point during which a pedestrian experiences the possibility of suffering an injury related to the act of being a pedestrian.â Several constructsâsuch as counts of pedestrians at crossingsâ can be used to quantify pedestrian exposure to the risk of a crash or injury. In theory, not all pedestrian trips or activities result in exposure to a vehicle crash, but for the purposes of this guidebook, the terms pedestrian exposure, volumes, demand, and activity are used interchangeably. RiskâProbability of a crash between a pedestrian and a motor vehicle at a specific location within a defined period. While true risks are rarely known, the traffic engineering field creates estimates of risk by identifying attributes of locations on a roadway network that are associated with crash frequencies or severities (see crash predictor definition). G L O S S A R Y O F K E Y T E R M S
Risk FactorâAny attribute, characteristic, or exposure of an individual or roadway that increases the likelihood of a crash or increases the risk of a more severe injury outcome in the event of a crash. Unlike a crash predictor, not all risk factors can be measured from attributes associated with site characteristics (such as states of users at the time of a crash). The mere presence of a risk factor may not be sufficient to cause a crash, but a risk factor should have a plausible association with a contributing circumstance of a crash. Safety Performance FunctionâA statistical model used to predict crashes based on site characteristics. These models always include motor vehicle traffic volume (AADT) and, in the case of pedestrian crash SPFs, should also include pedestrian volume (AADP). SPFs may also include other roadway features, and in the case of pedestrian SPFs, characteristics of the built and social environment around the site. Predictions (both adjusted for prior crashes and unadjusted) are used to estimate overall crash risk at a location. Surrogate MeasureâA characteristic or variable that may help to predict crashes by approxi- mating or capturing phenomena associated with a risk factor that may or may not be measured. A common example is the use of household or employment density (available data from the Census Bureau) to serve as a surrogate for pedestrian exposure, when the latter is not directly measured. Systemic ApproachâA systemic approach is a data-driven, networkwide (or system-level) approach to identifying and treating high risk roadway features correlated with specific or severe crash types. Systemic approaches seek not only to address locations with prior crash occurrence but also those locations with similar roadway or environmental crash risk characteristics.