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Presentation shows benefits of controlled merging through ramp metering

Three men stand in front of a lit traffic signal indoors.

Praveen Edara (center), an assistant professor of civil engineering, stands in front of a three-head traffic signal with graduate students Sawyer Breslow and Eric Zhu. The signal was used during Edara’s research on the effects and benefits of temporary ramp metering on highway entrance ramps.

Assistant Professor Praveen Edara presented the results from his research on temporary ramp meters at the Intelligent Transportation Systems (ITS) Heartland annual meeting in Topeka, Kan., in April. He and Associate Professor Carlos Sun conducted research with the assistance of graduate students to discover the effects and benefits of using traffic signals on the entrance ramps of highways near work zones.

“Kansas City has some permanent signals for alleviating traffic congestion on Interstate 435,” Edara said. “This research project was the first study to see how they affect work zones.”

Ramp meters are stoplights fixed at the end of an entrance ramp to a larger, often multi-lane highway. Their purpose is to control the merging traffic entering from the ramp, which affects the efficiency on the mainline of traffic. Unlike permanent ramp meters, which control merging traffic under normal conditions, temporary meters can change as the work zones do to control traffic that is already congested because of the work zone.

The research began with a Federal Highway Administration Smart Work Zone Deployment Initiative call for proposals from a five-state region in the Midwest, which was awarded to Edara and Sun in 2008. The Missouri Department of Transportation (MoDOT) purchased a three-head, movable signal for the purpose of this study, Edara said.

Edara’s study tested for compliance and effectiveness at seven locations in Columbia along Interstate 70 and U.S. Highway 63. These locations were convenient, he added, not only for their proximity to Columbia, but also for providing enough congestion to complete the study. Researchers used the three-head signal, as well as several pieces of video monitoring equipment to monitor the locations, including 25-foot tripod-mounted cameras and radar guns.

“We tested different types of signal timing configurations and found greater compliance with the three-head signal — green, yellow and red — rather than the typical two-head signals — just green and red — used as permanent ramp meters,” Edara said.

Data analysis included an examination of how traffic behaved on the entrance ramp, as well as in the mainline of traffic.

“This examination suggested that temporary ramp meters relieved congestion and improved mobility at congested work zones. And, they must be deployed at work zone locations where there is potential for congestion and turned on only during oversaturated conditions,” Edara said.

Edara is not the only person getting recognition for his work. His graduate student assistant, Eric Zhu, won first place in the poster session at the 2012 Traffic and Safety Conference for his work on the project.

ITS Heartland invited Edara to be one of the speakers at the organization’s sixth annual operations symposium. Edara said he received positive response to his presentation from representatives of other states’ departments of transportation.

ITS Heartland is a chapter of ITS America and serves as a platform for sharing data, projects and activities throughout its jurisdiction of Missouri, Iowa, Kansas, Nebraska and Oklahoma. The organization operates with support from all five states’ departments of transportation, major universities in each state and the Federal Highway Administration.