Durability Study

The main objective of this study is to compare the durability performance of different pavement marking materials measured over time. Durability is defined as both retained retroreflectivity and the visible presence of a pavement marking. In order to compare the durability of various materials, markings need to be subjected to similar traffic conditions. Furthermore, a reasonably high traffic volume is desired in order to illustrate the differences between materials in the short time available for the study.

To provide a true assessment of the cost-benefits of alternative pavement marking materials, it was decided that longline test decks were required, and that the National Transportation Product Evaluation Program (NTPEP) database would not suffice. The NTPEP database provides a good comparison of multiple pavement marking materials to a known baseline material, but cannot be extrapolated to provide the probable service life of a material in a long-line application. Accordingly, test decks are planned for installation in both Alaska and Tennessee. Each test section in a pavement marking test deck includes installation of the right edgeline, the laneline nearest the right edgeline, and transverse lines at the beginning, midpoint and end of the test section. The alternative pavement marking materials are installed in a grooved section of roadway, and on a section of roadway where the marking has been eradicated. Those pavement marking materials that are intended to provide interim maintenance are also applied directly over the preexisting pavement marking. In addition, some test sections include rumble stripes. Pavement marking materials are applied with long-line trucks, where possible, and hand-carts, when trucks are not available.

Retroreflectivity and photographic measurements will be collected along each longitudinal line (i.e., edgelines and lanelines) and transverse line. Retroreflectivity data will be collected using a handheld pavement marking retroreflectometer and a mobile retroreflectometer. The mobile unit will measure longitudinal lines only. The portable unit will be used to measure the edgelines and transverse lines. The handheld dataset will be used to evaluate the accuracy of the mobile unit dataset. If necessary, the handheld data will be used to correct bias in the mobile retroreflectivity data.

The mobile unit samples retroreflectivity along continuous 0.005 mile increments along each test section, and averages the values to provide a single value for that section. The research team will use the handheld retroreflectometer to measure the edgelines in each test section every 20 feet (i.e., about 400 measurements for each test section). The markings will be photographed using digital cameras to provide a record of pavement marking presence. Retroreflectivity and photographic measurements were collected after installation of the test decks in 2006 and again in the last quarter of 2006. They were also collected three times in 2007, and will be collected three times in 2008 and one time in 2009.

Alaska Durability Study

Tennessee Durability Study

Safety Study

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