Selection and Application of Warning Lights on Roadway Operations Equipment (2008)

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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 624 Subject Areas Maintenance • Safety and Human Performance Selection and Application of Warning Lights on Roadway Operations Equipment Ronald B. Gibbons Suzanne E. Lee Brian Williams VIRGINIA POLYTECHNIC INSTITUTE AND STATE UNIVERSITY Blacksburg, VA A N D C. Cameron Miller NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY Gaithersburg, MD 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. 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CRP STAFF FOR NCHRP REPORT 624 Christopher W. Jenks, Director, Cooperative Research Programs Crawford F. Jencks, Deputy Director, Cooperative Research Programs Amir N. Hanna, Senior Program Officer Eileen P. Delaney, Director of Publications Natalie Barnes, Editor NCHRP PROJECT 13-02 PANEL Field of Maintenance—Area of Equipment Erle Potter, Virginia DOT, Richmond, VA (Chair) John B. Arens, Vienna, VA Ralph D. Ellis, University of Florida, Gainesville, FL John C. Forman, South Dakota DOT, Pierre, SD Edward J. Hardiman, California DOT, Sacramento, CA Robert G. Lannert, Jefferson City, MO (formerly with Missouri DOT) Stephen A. Toth, New Jersey DOT, Trenton, NJ William J. Troup, US Fire Administration, Emmitsburg, MD Carl K. Andersen, FHWA Liaison Frank N. Lisle, TRB Liaison AUTHOR ACKNOWLEDGMENTS The research reported herein was performed under NCHRP Project 13-02 by the Virginia Polytechnic Institute and State University (Virginia Tech) and the National Institute of Standards and Technology (NIST). Virginia Tech was the contractor for this study; NIST served as a subcontractor. Dr. Ronald B. Gibbons, Group Leader, Lighting and Infrastructure Technology, Center for Vehicle Infrastructure Safety, Virginia Tech, was the principal investigator. Dr. Suzanne E. Lee, also of Virginia Tech, was the co-principal investigator on this project. The other contributors to this project were Mr. Brian Williams, Mr. Michael McNulty, Mr. Gregory Fitch, and Dr. C. Cameron Miller. The work was performed under the general supervision of Dr. Gibbons and Dr. Lee. The work conducted at NIST was performed under the supervision of Dr. Miller. 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 recommended guidelines for the selection and application of warn- ing lights on roadway operations equipment. The recommended guidelines address the physical, functional, and performance requirements of the lighting system, recognize that the lighting system on these vehicles must be designed and laid out with consideration to the planned or expected vehicle usage, and provide technical information for use in devel- oping procurement specifications for specific applications. The content of the report will be of immediate interest to maintenance professionals and others involved in specifying warn- ing lights on roadway operations equipment. Roadway operations equipment used for construction, maintenance, utility work, and other similar activities generally operate within roadway right of way. These vehicles and mobile equipment operate on all types of roadways, during day and night hours, and under all weather conditions. To improve motorist and work-crew safety, equipment must be readily seen and recognized and, therefore, warning lights are provided on the equipment to alert motorists of potentially hazardous situations. Amber warning lights have tradition- ally been used although lights of other colors are often added with the intent of helping the traveling public better see the equipment. Combinations of amber, blue, and white lights and other forms of warning lights (e.g., lighted bars, lighted “arrow sticks,” strobe, LED, and alternating flashing) are used. There is a concern that this variety of lighting on roadway operations equipment has evolved without adequate consideration of the effects on the awareness and responsiveness of motorists. In addition, there are no widely accepted guide- lines for selecting warning lights on roadway operations equipment that consider the type of equipment, weather conditions, day- and night-time operation, color of vehicle, and other relevant factors. Thus, research was needed to develop guidelines to assist transporta- tion agency personnel in selecting and procuring lights that will substantially enhance motorist awareness. Under NCHRP Project 13-02, “Guidelines for Selection and Application of Warning Lights on Roadway Operations Equipment,” Virginia Polytechnic Institute and State Uni- versity of Blacksburg, Virginia worked with the objective of developing guidelines for selec- tion and application of warning lights to improve the conspicuity and recognizability of roadway operations equipment used for construction, maintenance, utility work, and other similar activities. To accomplish this objective, the researchers conducted a review of cur- rent practices for use of warning lights on maintenance vehicles and an investigation to eval- uate several aspects of the warning light system. This investigation included photometric characterization, screening, and performance experiments to evaluate lighting parameters that influence system performance as defined in terms of glare and vehicle detectability. F O R E W O R D By Amir N. Hanna Staff Officer Transportation Research Board

Based on the results of this work, the research recommended guidelines for the selection and application of warning lights on roadway operations equipment, and proposed photo- metric limits for these warning lights. The recommended guidelines together with accompanying proposed photometric and technical information provide a basis for developing procurement specifications for warn- ing lights applied to roadway operations vehicles that will provide enhanced conspicuity and recognizability. Appendixes A through E contained in the research agency’s final report provide detailed information on relevant literature, the experiments performed, and data analysis. These appendixes are not published herein but are available on the TRB website at www.trb.org/ news/blurb_detail.asp?id=9632. These appendixes are titled as follows: Appendix A: Literature Review Appendix B: Identification of Relevant Factors Appendix C: Photometric Characterization Experiment Appendix D: Static Screening Experiment Appendix E: Performance Experiment

C O N T E N T S 1 Summary 5 Chapter 1 Introduction and Research Approach 5 Background 5 Objective 6 Report Organization 6 Literature Review 11 Identification of Relevant Factors 12 Chapter 2 Photometric Characterization Experiment 12 Experimental Method 12 Data Analysis 12 Summary of Results 14 Chapter 3 Static Screening Experiment 14 Experimental Methods 17 Summary of Results 21 Discussion 21 Preparation for Dynamic Performance Testing 22 Chapter 4 Performance Experiment 22 Experimental Methods 26 Summary of Results 30 Discussion 32 Chapter 5 Conclusions and Suggested Research 32 Conclusions 32 Considerations for Future Research 34 References 35 Attachment Proposed Guidelines for the Selection and Application of Warning Lights on Roadway Operations Equipment 40 Appendixes