Providing Parking Information Reduces Congestion

Research conducted at the National Transportation Center at Morgan State University will help provide relief for frustrated Washington, D.C., drivers as they hunt for an elusive parking space.

Based on the results of the study, Quantifying the Impact of On-Street Parking Information on Congestion Mitigation, the District Department of Transportation will use variable message signs (VMS) connected to parking meters to direct drivers toward open parking spaces.

The research, funded by the Mid-Atlantic Transportation Sustainability University Transportation Center, found that providing information about open spaces reduced time spent circling looking for parking which in turn reduced congestion and emissions.

"We expected that having information would reduce the time spent looking for parking, and we reached such a result," says Samira Ahangari, a Ph.D. student in Transportation at Morgan, who was one of the researchers. "When drivers have that information, they go directly to the parking space and they don't circulate."

To measure methods of providing information, the researchers created a realistic-looking simulation of D.C.'s Chinatown area in a driving simulator, and gave drivers instructions to proceed to the Verizon Center (now renamed the Capital One Center) and find parking. Drivers were given either no information about parking, information through VMS positioned at intersections indicating which direction to turn to find a space, or a parking app on their phones that used colors to indicate how many spaces were open. Drivers using the app checked it before they began driving.

The research, which used 76 drivers, found that without any information, drivers would circulate for six or seven minutes looking for a space. The VMS signs reduced that time by two minutes, while the app reduced circulation time by four minutes. Researchers at Virginia Tech collaborated in the study to determine which VMS signs worked best.

Both the VMS and the app had drawbacks. With VMS, the driver needed to use intersections where the signs were positioned in order to see them. Users of the app checked it before they began the five-minute drive to the Verizon Center; in the real world that app would need to update every minute or so in case someone took the space in the meantime. That raises additional issues of how to deliver information through an app without compromising safety.

But when it comes to reducing the time spent hunting for a space, "both are better than no information at all," Ahangari notes.

Ahangari's research will be published in the Transportation Research Record (TRR), Journal of the Transportation Research Board. The principle investigators for the project are Dr. Celeste Chavis and Dr. Mansoureh Jeihani from Morgan and Dr. Hesham Rakha from Virginia Tech.