Professors are designing a fleet of drones to check for cracks and rust on bridges.

Most bridges require a team of engineers to regularly do manual inspections of joints and beams to check for cracks, rust and other damage. Two professors from Tufts University are hoping to add some automation to the process by creating a system that uses vibration sensors to notify drones to fix any potential issues and alert engineers when they are needed, IEEE Spectrum reports.

Babak Moaveni is a civil engineering professor who has been working on a way to stay up to date on the structural health of bridges on a daily basis. In 2009, he and his students placed 10 sets of accelerometers and thermal sensors on the Dowling Hall footbridge on the Tufts campus. The sensors gather data every hour and relays five minutes of it to a server in a waterproof casing near the bridge. Moaveni and his team can then look for changes in the pattern of vibrations to detect damage. 

Moaveni is now working with Usman Khan, as assistant professor of electrical and computer engineering, to manage the system wirelessly. However, it requires quite a bit of energy for the sensors to transmit the data over long distances on a wireless network.

“Using a sensor to wirelessly communicate its collected data would drain its battery pretty fast,” Khan told IEEE Spectrum.

He proposes that drones can be used to download the information from the sensors, instead of having the sensors send the information to a server. The sensors could store the data on RFID tags and a small group of drones would go under the bridge to download information from the tags. They would then return to a charging station or mobile base to send the data to the server. These drones could also read the information and alert engineers if there is a potential issue.

“If a reading is off from normal the drone can be programmed to take pictures so we can see if there is rust on a nearby beam, for example," Khan said.

The drones could also have the ability to reprogram sensors themselves. The sensors could, for example, be programmed to only record data during rush hour. 

One major issue is navigation. The drones wouldn't be able to stay connected to GPS while under bridges. They could, however, navigate with the help of QR codes next to sensors. They would act as markers on a map and direct drones to the next marker. 

Khan and Moaveni hope to put together a full demonstration of the program on the Dowling Hall footbridge in the next couple of years.