Pavement Marking Demonstration Project: State of Alaska and State of
Tennessee-Report to Congress
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Almost $1 billion was spent nationally on pavement markings on State-maintained roads in 2007.
When local roads, private roads, and parking areas are included, it was estimated that approximately $2 billion was spent on pavement markings in 2007. Despite the national expenditures on pavement markings, according to a recent American Association of State Highway and
Transportation Officials (AASHTO) report, a highway death occurs every 21 minutes as a result of a lane departure. Prevention of roadway departure crashes is one of the Federal Highway
Administration’s (FHWA) four focus areas for safety. In addition, AASHTO has developed its Strategic Highway Safety Plan (SHSP) that is designed to reduce these crashes. The first
objectives of the FHWA focus areas and the SHSP are to keep vehicles in their lanes and on the roadway. Installing and maintaining effective pavement markings is one immediate and obvious way to meet these objectives.
Under Section 1907 of the Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users (SAFETEA-LU), the U.S. Congress directed the Secretary of Transportation to conduct demonstration projects in Alaska and Tennessee to study the safety impacts, environmental impacts, and cost effectiveness of different pavement marking systems and the effect of State bidding and procurement processes on the quality of pavement marking material employed in highway projects. The demonstration projects were to include an evaluation of the impacts and effectiveness of increasing the width of pavement marking edge lines from 4 inches to 6 inches and an evaluation of advanced acrylic waterborne pavement markings.
The major findings of the demonstration projects are summarized as follows:
A field observational study of edge line width on rural two-lane two-way (RTLTW) roads in Tennessee did not indicate a causative relationship between edge line width and safety. This study of driver performance through curves indicated that there were either no real or, at most, only subtle vehicle operational impacts as a result of adding or widening edge line markings—even for narrow two-lane highways—under both day and night conditions. However, an Empirical Bayes (EB) before-after analysis and an independent cross section analysis using historical data from Michigan and Illinois suggest that the installation of wider edge lines results in reductions in many single vehicle road departure crashes. These retrospective analyses
are considered more powerful than the observational study, as they incorporate several
years of actual crash data rather than a limited number of observations of driver performance. Additional refinements of the retrospective analyses are ongoing and will be presented in a final
research report to the FHWA.
The industry has responded to various Federal and State requirements for pavement marking materials that are environmentally benign and reduce the risk to people from manufacturing to application and removal of materials. While no research has been conducted to date on the amount of airborne lead released when encapsulated lead-pigmented thermoplastic markings are
removed from the roadway, the industry has developed lead-free and chromate-free thermoplastic markings, and State agencies are quickly adopting them. An evaluation of the potential environmental and health impacts of heavy metals in glass beads used in pavement
markings was beyond the funding limits of this study.
Preliminary findings indicate that States are pursuing alternative procurement strategies to provide high-quality, durable markings in a cost-effective manner, often as part of their required State SHSPs. While this current study did not conclusively demonstrate that a performance-based specification for pavement markings or a warranty-based contract results in higher quality installations, States are moving to these programs as a means of enforcing minimum standards for pavement marking systems. The effort that State and local agencies expend on the installation and
maintenance of pavement markings indicates that these agencies are exercising due diligence in meeting their fiduciary responsibilities for providing a critical public service at the lowest possible cost, and flexibility in State procurement processes should be maintained.
Differences in traffic volumes, types and patterns, roadway surfaces, installation practices, and environmental conditions interact in ways that make it difficult to formulate general statements regarding the most cost-effective means to provide pavement markings that meet the needs of the driving public during the day and night. While advanced waterborne acrylic
markings have performed adequately in the Tennessee demonstration project, they did not survive the winter season in Alaska. In fact, as of this report, all of the alternative pavements marking
systems installed as part of the demonstration project in Tennessee are still considered acceptable and require additional exposure to traffic and weather in order to develop recommendations regarding cost effectiveness. The test decks in Tennessee were monitored for
pavement marking performance through the 2009–2010 winter, and the results will be included in a final research report to the FHWA.
Conditions in Alaska prove to be a harsh environment for pavement markings of any type. Most of the markings tested in Alaska were deemed to provide inadequate guidance to drivers after the first winter, even when installed in a recessed groove to minimize plow damage. In order to provide some level of guidance for drivers year round, Alaska has developed a process of
using waterborne paint and glass beads to refresh durable markings that lose retroreflectivity but not presence over the winter. This appears to be a viable solution for regions such as mountain pass roads in northern States that experience winter conditions similar to those in Anchorage, AK.
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