Warning system could protect drivers from traffic ‘shock waves'

Two years ago, the Minnesota Department shockwavesof Transportation (MnDOT) installed electronic message boards on parts of Interstates 35W and 94 to help warn drivers of crashes and to recommend speed levels during periods of high congestion.

Now, researchers at the Minnesota Traffic Observatory (MTO) are using these message boards as part of an automated warning system that will identify suddenly stopping or slowing traffic. When the system detects these problematic traffic patterns, it will issue automatic advisories to drivers. The goal is to help prevent the crashes that occur when drivers can’t react quickly enough to these changes.

As they develop the system, researchers will consider traffic patterns in two locations: a portion of I-94 in downtown Minneapolis and the I-35W/Highway 62 interchange.

“There’s a crash every two days,” says MTO director John Hourdos, whose students watched more than a year’s worth of video footage to document every crash and near crash. “They’re not severe crashes—no one has died for as long as I can remember, and most happen at slow speeds—but they cause a lot of delays for the traveling public.”

In 2002, the MTO deployed cameras and sensors on three downtown rooftops to observe traffic patterns on this portion of I-94. The equipment provides seamless coverage of the entire area, allowing researchers to watch vehicles from the moment they enter and exit the area. As part of a research project funded by the Intelligent Transportation Systems Institute, the researchers used data gathered from the cameras and sensors to develop an algorithm that detects shock wave patterns at this location.

Now, the team will use this algorithm to help develop the warning system, which will use the newly installed electronic message boards to warn drivers when conditions for shock waves are greatest.

The second problem area that researchers will target as they develop the warning system is I-35W southbound at the newly reconstructed Crosstown interchange. Although two lanes of traffic are provided for eastbound Highway 62 at the I-35W/Highway 62 split, these vehicles must later converge into one lane because of the Portland Avenue exit. This causes traffic congestion on the Highway 62 ramp that stretches back to I-35W during rush hour.

Hourdos says developing an algorithm to detect these queues is a different problem than what goes on with I-94, since there is a constant stoppage of cars and no rolling shockwaves.

“These two locations are good representatives of different manifestations of the same problem,” Hourdos says. “The methodologies for approaching each location will be different, but by combining them we will form a more robust warning system that can work in most situations,”

The research team may also target other specific problem areas if MnDOT installs additional electronic message boards elsewhere in the Twin Cities.

Adapted from an article published on the joint MnDOT/CTS Crossroads blog.