MnDOT signs will alert motorists to construction

ST. CLOUD (AP) -- The state Department of Transportation on Wednesday unveiled a system of automated signs that will warn highway motorists about traffic congestion in construction zones.

The system uses sensors, placed in the center of the roadway in the work zone, that send information about traffic volume and speed to a mobile monitor and LED traffic sign display a few miles away. The system is powered by solar energy and communicates via cellular technology.

Every few minutes, the system calculates the average traffic speed and informs approaching motorists of the conditions. Above 55 mph, the system shuts down, while below 20 mph, it warns motorists of stopped traffic ahead, said Craig Mittelstadt, MnDOT engineering specialist.

"This system will alert them 5 or 10 miles back, to let them find alternate routes or at least prepare them," Mittelstadt said.

The system will be used this summer, first in the Twin Cities area, MnDOT said.