Research has found that unmanned surface vehicles (USVs) can be more effective at inspecting bridges than current methods.

The USV is is a remote-piloted drone boat called Sonar EMILY (EMergency Integrated LanYard). It’s about 4 feet long, 2 feet wide and a foot tall. Its sonar units can measure water depths and produce side-scan and down-scan images of bridge streambeds and structures. The system also comes with a top side camera to see the underside of the bridges.

Traditionally, inspectors have found scour, the degradation of streambed around a bridge’s substructures, by probing the channel bottom with metal rods, weighted tape measures or sonar devices. When water levels in rivers and streams rise, this process can be hazardous to the inspectors.

Sonar EMILY would be a safer alternative and reduce the workload of the inspectors.

”Using the USV is much safer and less labor-intensive than traditional inspection methods for detecting scour,” said Chad Skrocki, MDOT’s project manager for the research. ”It provides a great deal of information, in real time, to the inspector about what is occurring to the channel bottom below the water surface around the bridge substructures.”

EMILY was originally created for researching marine mammals, but because it’s a versatile drone boat, it can be rewired to sample water and map underwater areas.

The cost of the USV, laptop control unit and equipment would cost around $50,000.

MDOT is planning to put four USVs and sonar units throughout the state to inspect bridges for scour during high-flow events. To prepare for releasing the USVs, MDOT trained bridge inspectors in April.

The unmanned vehicles could set a precedent for future ways transportation inspectors oversee their operations.