Making a mark: Contrast pavement strips create safer roadways

Crashes from vehicles departing from the roadway account for 51% of all fatal injury crashes in the U.S., according to the Federal Highway Administration.

To reduce this percentage, Illinois Center for Transportation and Illinois Department of Transportation investigate pavement markings in their joint project, “R27-223: Crash Modification Factors for Contrast Pavement Markings on Light-Colored Pavement.”

Michael Williamson, Indiana State University associate professor, leads the project with Marshall Metcalf, IDOT’s traffic unit project implementation engineer.

Williamson and Metcalf investigate contrast pavement markings, a lane-marking design used on light-colored pavement to make the markings more visible to motorists.

Contrast pavement markings have been used by transportation agencies to improve roadway safety, but their safety effects have never been quantified.

The research team sought to calculate the markings’ safety benefits by conducting a nationwide survey of departments of transportation regarding their current trends and use of the markings.

They then compiled a database of 1,774 crashes, including key site-specific details from 70 miles of roadway across six states.

From the data, they developed first-of-a-kind crash modification factors — or the expected number of crashes after implementing the markings — for roadways with four, six or eight lanes and three crash severity levels.

Installing contrast pavement markings reduced total crashes between 12%-29%, depending on the roadway type, while fatal injury crashes decreased 7%-19% and crashes involving only property damage decreased 5%-16%.

The research team credits their success to the various transportation agencies that participated in the survey or provided data.

Key to the research is a user-friendly benefit-cost tool developed by Williamson.

The tool presents the estimated benefits associated with contrast pavement markings in terms of dollars and crash reductions.

“One of the goals of the project was to come up with a way of quantifying or justifying the extra dollars that have to be spent on these contrast markings,” Williamson said. “So, the tool takes into consideration localized factors and then calculates the savings in terms of crash reductions.”

Users can input factors such as the length of a roadway segment, amount of traffic, and crash history as well as account for the life span of the pavement marking and inflation rates.

From those factors, the tool will automatically calculate a benefit-cost ratio that can be used to justify the use of contrast pavement markings on new projects.

“We were very pleased that there’s a tool created out of the research that’s simple to use,” Metcalf said. “There’s not a lot of research necessary to plug into this tool and do a quick confirmation if contrast markings are a valuable addition to a project.”

Contrast pavement markings are expected to have an additional benefit: aiding lane-keeping assist systems in vehicles.

“There’s a very high market penetration of normal vehicles that the average person buys that detect the lane markings and lets people know when they’re perhaps a little inattentive and getting outside of their lane,” Metcalf said.

“So, we were really glad to perhaps make those lane markings work better, so people will leave those safety devices on, and they’ll work properly,” he added.