BRIDGE MAINTENANCE: Purdue University researchers employ new set of sensors to determine bridge weight-limit accuracy

March 27, 2017

The researchers were supported by state agricultural councils and programs

A team of research technicians from the Bowen Laboratory at Purdue University’s Lyles College of Civil Engineering recently employed a sensor system developed by the Bridge Engineering Center at Iowa State University on the CR 250 E bridge in Lebanon, Ind., for a load bearing test that could determine whether the 77-year-old structure’s 12-ton weight limit is accurate.

The sensors are connected to the underside of the structure and electronically relayed to equipment in a high-roof van parked on the south side of the bridge. It is hope that the technology can replace current visual inspection, which can over- or under-estimate a bridge’s condition, leading either to unnecessary closures or potential safety risks.

Representatives from the Indiana Corn Marketing Council, the Indiana Soybean Alliance and Purdue’s Local Technical Assistance Program were on hand, along with local farmers to witness the process.

While the results of the test will not be available for several weeks, according to Megan Arnold, of the Sandbox Agency, a publicity agency working with the soybean alliance and corn council, once it is prepared data from the test will be given to the company that provides bridge weight limits to the county. A comparison will then be made against previous weight-limit estimates to produce a “real world” load rating.

The CR 250 E bridge was built in 1940, and while it is considered to be in “good” condition, the concrete slab structure shows obvious signs of deterioration. A 3-ft-long rusted rent mars a steel culvert on the northeast corner of the abutment. The narrow bridge also limits access by farm equipment.

More information about the bridge test and the economic impact of aging infrastructure in Indiana is available at