ICT-IDOT project puts all-weather road markings to the test

Roadways can be treacherous at night when it is raining and everything looks like a shining surface. With everything looking the same, it can be difficult for drivers to see the pavement markings to keep their bearings on the road. To combat this problem, several companies have released special pavement marking products in the past few years designed to work in adverse conditions so that the markings stand out from the surrounding pavement, even when wet.

These products were the focus of a recent project sponsored by the Illinois Department of Transportation (IDOT) and administered by ICT. Primary Investigator Neal Hawkins and his co-investigator Omar Smadi, both of Iowa State University, recently completed a project, “Evaluating All-Weather Pavement Markings in Illinois” (R27-120), in which they and their team sought to evaluate, both in the lab and in the field, the initial effectiveness of these pavement marking products and their continued effectiveness over time. They did this with a combination of lab investigations and in-the-field measurements, with an eye toward determining which, if any, were the best investment for the state to make.

“The need for providing guidance when the road conditions are less than ideal (rain, sleet, or snow) is critical for the safety of our drivers,” project Technical Review Panel (TRP) chair Kelly Morse explains. “Providing delineation helps the driver make better decisions under adverse conditions and to get them safely to their destinations.”

The study consisted of 27 different product combinations subjected to two evaluations: a field study performed on various roads throughout Illinois and a lab study that attempted to replicate long-term wear on the test products. The field study showed, first, that less than half the products met the minimum requirements examiners established, and only 4 out of the 27 products met the threshold after 2 years of field wear.

The lab portion of the study produced mix results. The initial lab results correlated well with the field results, but when compared with one- and two-year field data, the variability in the measurements reduced the researchers’ confidence in the lab results. The research team was able to acquire some useful data, such as curves showing the decay of the materials, which can be applied to future efforts in this area. The main issue in the lab was the challenge of adapting lab equipment to simulate field conditions.

Accelerated wear in the laboratory using 3 steel wheels

“The findings of this research project,” explains Morse, “demonstrate that the technology currently available does not have the durability necessary to withstand the wear factors on our roadways. The need for further study on the premanufactured all-weather products and the improvement of the durability of all-weather media used in and on the marking materials is necessary for the success of all-weather pavement markings.”

These preliminary results have laid the foundation for a second phase of this project that will examine either the best way to use an existing product to maximize success or the qualities needed in a successful product in order to advise manufacturers on the state’s needs.