EAST LANSING, Mich. — A Michigan State University engineering professor plans to place sensors on the Mackinac Bridge later this month to monitor stress on the aging structure.

Professor Nizar Lajnef tells the Lansing State Journal (http://on.lsj.com/2c6ctBq ) the stress sensors are a test of a project he’s been working on for seven years with funding from the Federal Highway Administration.

A recent grant of $1.5 million to MSU, Washington University in St. Louis and the University of Nevada-Reno will put sensor prototypes in place at several spots around the country. He says if it works, the stress sensors could become commonplace on structures around the country.

“We don’t have to wait until it’s broken and then try to fix it,” he said. “We’re trying to monitor its health over time.”

The 5-mile-long Mackinac Bridge that connects Michigan’s Lower Peninsula with the Upper Peninsula is the third-longest suspension bridge in the world. About 3.9 million vehicles crossed it in 2015.

“People have been trying for a long time to design methods to assess the condition of bridges,” Lajnef said.

Lajnef’s team created a sensor that charges itself from the energy of movement across the bridge, so it requires little in the way of maintenance. He projects the production cost to be less than $1 apiece.

The sensors wirelessly transmit data about the structure’s response to traffic. After a baseline is created, any variance could indicate a problem.

“When the stresses are outside the normal range, the sensor will tell you so that you can fix it before it is too late, before the components break,” he said.

Lajnef expects to install six sensors on the bridge in mid-September. If they perform as expected, more will be added in the spring. The bridge could eventually contain hundreds of sensors.


Information from: Lansing State Journal, http://www.lansingstatejournal.com