National Academies Press: OpenBook

Applications of Illuminated, Active, In-Pavement Marker Systems (2008)

Chapter: Chapter One - Introduction

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Suggested Citation:"Chapter One - Introduction." National Academies of Sciences, Engineering, and Medicine. 2008. Applications of Illuminated, Active, In-Pavement Marker Systems. Washington, DC: The National Academies Press. doi: 10.17226/14182.
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Suggested Citation:"Chapter One - Introduction." National Academies of Sciences, Engineering, and Medicine. 2008. Applications of Illuminated, Active, In-Pavement Marker Systems. Washington, DC: The National Academies Press. doi: 10.17226/14182.
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Page 7

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7PROBLEM STATEMENT Various types of illuminated, active, in-pavement marker (IPM) systems are emerging that offer a range of designs and functional features intended to warn, guide, regulate, or pro- vide illumination for road users. Compared with traditional retroreflective pavement markers (RRPMs), IPM systems can provide a greater level of information to the road user through the use of various marker color changes to indicate regulatory action (e.g., markers show red illumination when vehicles are required to stop), flash rates indicative of the level of hazard, or “chase” sequences directing the road user to reduce or increase speeds. These systems also offer the potential for increased visibility over traditional RRPMs, particularly through horizontal curves. RRPM systems function by re- flecting light from a vehicle’s headlights. Hence, the entire extent of some horizontal curves cannot be illuminated by RRPMs. On the other hand, IPM markers can be designed to provide illumination from a wider range of viewing angles; giving a more consistent, complete, and clear indication of road curvature. For this synthesis effort, IPM systems also include lighted devices that are not “in-pavement” but are mounted on concrete barriers or sign posts. Historically, IPM system use was limited to airport runway/ taxiway or pedestrian crosswalk applications. More recently, IPM systems have been used to: (1) enhance warning through school and construction zones, at highway–rail crossings, at horizontal curves, and during adverse weather; (2) provide guidance through multiple-turn lanes, at merge locations, and through tunnels; (3) enhance regulation at intersection stop bars and where left turns are prohibited; and (4) enhance illu- mination at vehicle and truck inspection points and environ- mentally sensitive areas. Although the number and breadth of IPM system applica- tions has increased in recent years, it appears that little is known about the true effectiveness of these systems in enhanc- ing roadway safety, operations, or aesthetics. Furthermore, it is evident that little guidance is available to support proper installation, operation, and maintenance of the systems. OBJECTIVES This synthesis report documents the current state of knowledge related to IPM system use and effectiveness. More specifi- cally, the report documents: (1) the state of IPM technology, including technology characteristics and standards and guide- lines for use; (2) notable experiences from historical IPM system applications; and (3) detailed experiences from more recent IPM system applications, including system and facility characteristics, operation modes, installation and construc- tion methods, maintenance requirements, system costs, and perceived and measured effectiveness. Assimilated in this synthesis report, this information will help to accelerate successful applications and focus future re- search of IPM systems. METHODOLOGY Information to support this synthesis effort came from three primary sources: • A review of published literature, • A formal survey of transportation practitioners, and • An informal survey of IPM system vendors and users. Supplemental information was also provided by various NCHRP Synthesis Topic Panel members and through infor- mal interviews with traffic engineers, researchers, and other industry professionals. Literature Review As a first step in this synthesis effort, a review of published literature was conducted. A full range of domestic and inter- national IPM system applications, including airport and pedestrian crosswalk applications, were considered. Primary sources of literature included: • Transportation Research Information System (TRIS); • International Transport Research Documentation (ITRD) database, which includes transportation research of 23 countries; and • Conference compendiums such as TRB’s annual meet- ing and ITE district and international meetings. Not surprisingly, much of the published literature related to airport and pedestrian crosswalk applications. IPM systems are more widely implemented and have a longer history of use in these environments. Limited information was also uncov- ered related to the use of IPM systems during adverse weather. CHAPTER ONE INTRODUCTION

Transportation Practitioner Survey To supplement information obtained through the literature review and to capture a broader array of practical information related to IPM system use and effectiveness, a survey ques- tionnaire was developed and distributed to numerous state and local traffic engineers. Specifically, the questionnaire was dis- tributed to state traffic engineers from all 50 states, the District of Columbia, and Puerto Rico; traffic or public works engineers from the top 200 metropolitan statistical areas of the United States; and to the ITE Traffic Engineering Council Listserv. A total of 865 contacts were invited to complete the survey. The survey questionnaire (see Appendix A) was designed to capture information for a wide range of potential IPM system applications (e.g., construction zones, highway–rail cross- ings, horizontal curves, adverse weather, multiple-turn lanes, merge locations, variable-width lanes, tunnels, intersection stop bars, left-turn restrictions, restricted and emergency use lanes, vehicle and truck inspection points, environmentally sensitive areas, and other applications). The survey question- naire intentionally omitted pedestrian crosswalk applications to avoid duplication of previously documented findings. Following brief introductory material describing the proj- ect background and objectives, survey respondents were asked to describe IPM system • Applications in their jurisdiction (and the characteris- tics of the facility that hosts the IPM system), • Technology and respective characteristics, • Installation and construction methods and challenges, • Operation modes, • Maintenance requirements, • Costs, and • Perceived and measured effectiveness. In an attempt to achieve a higher response rate and to ex- pedite return, this survey was distributed electronically. Each contact was sent an invitation e-mail with a brief description of the synthesis project and instructions on how to locate and begin the survey. The online survey was designed with a gate- way feature that allowed each invitee to log in to the survey using his or her e-mail address and a unique identification number (which was provided in the invitation e-mail). In addition, a persistence feature was used to allow the respon- dent to close the survey and return to it at a later time using the login information provided. The gateway and persistence features also allowed a respondent to forward the survey to another individual for full or partial completion. Despite attempts to encourage response, only 62 of the 865 invited contacts completed the survey (7.2% response rate). 8 Of the 62 respondents, 47 indicated that they did not know of any IPM system applications within their agency’s jurisdic- tion. An additional 10 respondents provided information re- garding IPM system applications at pedestrian crosswalks. Only six contacts provided information about non-crosswalk applications of IPM systems. Although the low number of affirmative survey responses was disappointing, it was not surprising because IPM systems are still a relatively novel treatment for public roadways. A list of survey respondents is included in Appendix B. Vendor Survey To supplement the information obtained from both the litera- ture review and the transportation practitioner questionnaire, a comprehensive informal survey of IPM vendors was con- ducted (a list of IPM system vendor contacts is included in Appendix C). The purpose of the vendor survey was twofold: (1) to identify additional IPM system applications that were not uncovered through the literature review or transporta- tion practitioner survey, and (2) to provide detailed product information including technical specifications, operational performance, maintenance requirements, and system costs. In some cases, the vendor contacts were able to provide ad- ditional public agency transportation practitioner points of contact for specific applications. In addition, vendor contacts provided information about potential IPM system applica- tions that are not yet field-tested but are in the conceptual stage. Information obtained through this vendor survey may re- flect an inherent bias. To minimize this bias, information was solicited from a wide range of vendors and tempered with in- formation obtained by public agency transportation practi- tioners to the extent possible. REPORT ORGANIZATION Following the introductory information in this chapter, chap- ter two describes the state of IPM technology, including tech- nology characteristics, standards, and guidelines for use, and notable experiences from historical IPM system applications. Chapter three details experiences from more recent IPM sys- tem applications, including system and facility characteris- tics, operation modes, installation and construction methods, maintenance requirements, and system costs, as well as perceived and measured effectiveness. Applications are cate- gorized by their intent: to warn, to guide, to regulate, or to provide illumination for road users. Chapter four concludes the report with a summary of key findings and provides appli- cable recommendations based on the information obtained in this synthesis effort.

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TRB's National Cooperative Highway Research Program (NCHRP) Synthesis 380: Applications of Illuminated, Active, In-Pavement Marker Systems (IPMs) explores the state of IPM technology, experiences with IPM applications, and potential IPM research needs.

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