Practices to Manage Traffic Sign Retroreflectivity (2012)

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3 Roadway traffic signs are a primary means of communicating critical information to roadway users. The Manual on Uni- form Traffic Control Devices (MUTCD) provides the basic principles that govern the design and use of traffic control devices for all roadways open to the public (1). There are five main principles in the MUTCD that traffic control devices must follow: 1. Fulfill a need, 2. Command attention, 3. Convey a clear simple meaning, 4. Command respect from road users, and 5. Give adequate time for proper response. Traffic signs are also classified into three primary des­ ignations: regulatory, warning, and guide signs. Each clas­ sification serves a distinct purpose and adheres to strict and uniform design standards. Regulatory signs inform of traffic laws or regulations, warning signs give notice of a situation that might not be readily apparent, and guide signs provide destination information such as directions, distances, and points of interest. Sign information can be conveyed through the legend, which can be comprised of words, symbols, and arrows. Road users can also extract information from a sign’s unique appearance, with size, color, and shape critical components. In addition to the specialized design criteria, road users need to detect signs and comprehend the message content in a timely manner in both daytime and nighttime. At night, signs not internally illuminated must be fabricated with retroreflective materi­ als. Light from a vehicle’s headlamps is reflected from the sign’s surface back to the driver giving the sign an illumi­ nated appearance. Background In 1993, the Secretary of Transportation was required by Congress to revise the MUTCD to include “a standard for a minimum level of retroreflectivity for pavement markings and signs which apply to all roads open to public travel” (2). The goal of the new minimum retroreflectivity requirements was to improve safety on our nation’s streets and highways, and was meant to ensure that drivers, especially the elderly, would be able to detect, comprehend, and react to traffic signs accordingly and help to facilitate safe, uniform, and efficient travel. To satisfy the congressional directive, FHWA added a table containing minimum sign retroreflectivity values to the Manual (section 2A.08 of the 2009 MUTCD). In addition, several methods are identified that agencies can implement to maintain traffic signs at or above the minimum retro­ reflectivity requirements. The next section expands on both the requirements and approved maintenance methods. Establishing sufficient and acceptable minimum retro­ reflectivity levels has been an ongoing collaboration of several different studies. In 1993, Paniati and Mace (3) established minimum requirements for regulatory, warn­ ing, and guide signs. The researchers developed a computer analysis program that incorporated various driver, vehicle, and roadway parameters. The program computed the mini­ mum required visibility distance for various inputs, which ultimately generate minimum retroreflective values. In 1995, Mercier et al. (4) confirmed that Paniati and Mace’s minimum requirements would sufficiently meet the needs of an aging driving population. This research team mea­ sured the luminance thresholds for various traffic signs in a laboratory setting and determined that the minimum levels would meet the needs of 85% or more of all drivers. In 2004, Carlson and Hawkins (5) established the final FHWA minimum retroreflectivity requirements, those that are used today. Their research utilized methods from the Paniati and Mace study, but incorporated new inputs to reflect recent developments in vehicle headlamps, changes in fonts, vehicle types and sizes, drivers’ nighttime needs, and the latest sheeting materials. Carlson and Hawkins also employed a new analysis tool that computed retroreflectivity requirements for traffic signs in various positions (right, left, and overhead) on the roadway. The final minimum levels were adopted by FHWA and are contained in Table 2A­3 of the 2009 MUTCD (1). The requirements exclude blue and brown signs and also parking, walking/hitchhiking/ crossing, pedestrian, adopt­a­highway, and bike signs. Also restricted are the uses of specific retroreflective materials in certain sign applications. Merely establishing and documenting minimum retro­ reflectivity levels was not the sole objective. The key element in the standards is maintaining sign retroreflectivity at or above the minimums. To establish a level of compliance, FHWA established three important compliance dates (on August 31, 2011, a notice of proposed amendments was published in the Federal Register recommending that the compliance dates for sign retroreflectivity be modified. As of March 2012, chapter one IntroductIon

4 FHWA has not responded to the comments. For the latest information, see http://mutcd.fhwa.dot.gov/): • January 2012: Implementation and continued use of an assessment or management method that is designed to maintain traffic sign retroreflectivity at or above the established minimum levels. • January 2015: Replacement of regulatory, warning, and post­mounted guide (except street name) signs that are identified as failing. • January 2018: Replacement of street name signs and overhead guide signs that are identified as failing. With regard to the first compliance date, the 2009 MUTCD states “Public agencies or officials having jurisdiction shall use an assessment or management method that is designed to maintain sign retroreflectivity at or above the minimum lev­ els” (1). Traditionally, each agency manages and maintains its traffic signs in a manner that best accommodates their spe­ cific conditions, resources, and priorities. For this reason, the MUTCD allows for the flexibility to select and modify one or more methods to best fit the needs of each entity. The second and third compliance dates deal with the replacement of existing signs that are below the minimum levels. Each agency will encounter different circumstances when addressing these two compliance dates. Some proactive agencies may have few signs to replace, while others may have to replace a large portion of their sign population. A recent study by Opiela and Andersen (2007) estimated that the two compliance mandates will cost the nation approxi­ mately $37.5 million (6). It is estimated that the 2015 compli­ ance will cost state and local agencies $5 and $11.5 million, respectively, and the 2018 compliance requirements will cost $6.8 and $14.2 million, respectively. At a more focused level, the Indiana Local Technical Assistance Program (LTAP) Center conducted a similar study, which calculated that the state would need $14.2 million to bring all public roadway signs into compliance (7). Initial findings concerning the benefits of upgrading signs appear to justify the costs. A demonstration project was car­ ried out recently in Mendocino County, California (8, 9). The county is located in Northern California and the transportation authority at the time was responsible for maintaining approxi­ mately 1,000 centerlines. Over a three­year period, the county improved the current sign inventory by using two different approaches. The first approach addressed sign placement and uniformity by conforming to state standards. The county tar­ geted signing at locations with safety concerns and eliminated all nonstandard signing. The second approach upgraded all ASTM D4956 Type I signs with Type III signs. The combina­ tion of more uniform signing practices and brighter sheeting materials has reduced traffic crashes. The county analyzed 19 different roadways over a six­month period. County roadways with enhanced signing saw a 42% reduction in crashes, whereas nearby control roads experienced an increase in crashes of 27%. The sign enhancement program cost the county about $79,000 and it was estimated that the crash reduction savings ranged from $12.6 to $23.7 million. SyntheSIS oBjectIve An agency will essentially be in compliance with the new MUTCD minimum sign retroreflectivity standard if they have a method in place and can demonstrate that they are acting in good faith to implement that method. FHWA acknowl­ edges that an agency would be in compliance even if there are some individual signs that do not meet the minimum retro reflectivity levels at a particular point in time (1). For the most part, the key element is selecting and implementing a suitable method to maintain traffic sign retroreflectivity. Many public agencies have been aware of the approaching compliance dates for some time. There are proactive state and local entities that have acceptable methods in place and already meet one or more of the mandates, whereas others are just beginning to identify a suitable sign replacement method. There is a great deal of knowledge and expertise that can be derived from such proactive agencies and it is impor­ tant to assess how certain methods have been implemented and to what degree of success. The objective of this synthesis study was to provide exam­ ples of effective practices that illustrate how agencies can meet the retroreflectivity requirements, and also to document the state of the practice and make the results available to assist other agencies that are exploring different methods for main­ taining sign retroreflectivity. Key issues will also uncover gaps in knowledge, determine future needs, and identify new areas of research. Study approach Information for this synthesis study was acquired from three distinct sources: published research, existing guidance and policy, and telephone surveys. Initially, a literature review of research was conducted. Most of the research dealt with scientific and structured studies, and most of these research studies had definitive results and clear recommendations, such as documenting vandalism rates or evaluating retro reflectivity technology. The second source of information included Inter­ net websites, agency newsletters, or past Power Point presenta­ tions. Two examples were the Washington State Department of Transportation’s (DOT) Traffic Sign Retroreflectivity website and Minnesota DOT’s Traffic Sign Maintenance/ Management Handbook. Although the research and existing guidelines were vital components for this synthesis study, the majority of the information came from telephone surveys. Appendix A contains a list of useful resources for agencies just starting to acquire a familiarity with the sign retro reflectivity requirements.

5 Survey design The primary focus of this synthesis study was conducting telephone surveys. The goal of the surveys was to identify what methods have been implemented and which have shown promise. The survey questions were designed to facilitate and engage the study participants in a more structured discussion of sign practices at his or her agency. The survey question­ naire included 14 main questions most of which were open­ ended. In some situations there were follow­up bullets points if obtaining additional information was pertinent. The major issues the survey addressed were to identify: • The size and scale of the agency’s traffic sign activities, • How proactive the agency has been with sign replacement, • General opinions and apprehensions about the MUTCD retroreflectivity requirements, • How their method complies with the MUTCD and why it was selected, • How their method functions and the major operational advantages, and • Challenges encountered in the implementation process and lessons learned. Appendix B contains a copy of the survey questions and the telephone script that was read to the participants about the purpose of the survey. One goal of the survey was to obtain a wide range of participants. The survey participants needed to reflect various situations throughout the country such as differing agency size, regional climate, population density, and environmental conditions. Targeted survey participants included local agencies (cities, towns, and counties), state DOTs, LTAP centers, and private organizations. At the onset of the study, a list of possible survey candidates was estab­ lished, some of which came from Topic Panel recommen­ dations and from personal contacts; however, the majority came from specific requests. Presentations were also made at different meetings, such as National Committee on Uniform Traffic Control Devices, TRB, and American Traffic Safety Services Association to generate interest in the project. Ulti­ mately, surveys were e­mailed to different list groups and municipal organizations to solicit participants. Candidate response rate and survey participants are discussed later in the report. The survey questions were e­mailed to participants prior to scheduling a time for an interview; therefore, individuals had time to prepare their responses. During the telephone survey, the questions served as a guide for a general discus­ sion about traffic sign issues and practices. The discussion could periodically deviate from the question list if the par­ ticipant had important information to share or if there was any additional follow­up inquiry. Notes obtained from the survey participants were compiled and beneficial informa­ tion was documented. organization of report The first chapter lays the foundation for the succeeding material by describing the purpose of the study, states over­ all objectives, and explains the methodology to achieve its goals. Chapter two presents basic information on the differ­ ent assessment and management sign methods outlined in the MUTCD. The majority of the survey participants’ informa­ tion is contained in chapter three, and chapter four includes four selected Case Studies that expand on useful strategies. Chapter five summarizes the effective practices and chapter six describes areas where information is needed and sug­ gestions for possible future research. Finally, chapter seven concludes by summarizing key findings from chapters two through six.