Four years ago, the I-35 W. bridge in Minneapolis collapsed in an instant, falling into the Mississippi river killing 13 people and injuring 145 more.

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In 2005, the bridge was deemed to be “structurally deficient” – a term meaning it requires repairs but isn’t unsafe.

Mehdi Kalantari, a University of Maryland researcher, is concerned that other bridges are at-risk.

“The Minneapolis incident was just the tip of an iceberg,” Kalantari.

Nationwide, more than 70,000 bridges are considered to be “structurally deficient,” including 19 in the District and more than 1,200 in Virginia and about 375 in Maryland.

“The overall transportation infrastructure needs more high-tech technology,” Kalantari said.

To restore safety, Kalantari has developed a way to track a bridge’s structural integrity using wireless sensors. He’s partnering with the Maryland State Highway Administration to test the Northwest Branch Bridge. It’s been selected because it’s older, in need of basic repairs and located on the Beltway.

“You've got 230,000 vehicles and trucks pounding capital beltway every day- it's important we stay ahead of the curve,” said David Buck, spokesman for the Maryland State Highway Administration.

The small sensors, powered by ambient light, measure temperature, strain, vibration and any sign of cracks in real time.

That’s compared to Maryland’s Bridge Safety Program, which requires inspection once every two years.

“It really is crucial that you look at this type of technology to feed you data constantly instead of just once every two years when engineer takes a look,” Buck said.

Kalantari believes the technology could have prevented what happened in Minneapolis.

Maryland’s State Highway Administration says the sensors would not replace engineers going out t the physically inspect bridges. But they could be used to supplement those inspections if given federal approval.