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The inspection of road tunnels is operated regularly in order to detect anomalies. Drones may now replace inspection teams in this demanding task. The Land Transport Authority (LTA) in Singapore is weighing the option of using drones and other unmanned systems in inspecting Singapore’s underground railway systems. It has issued a Request for Information (RFI) to seek the industry’s participation in the use of Unmanned Aircraft Systems (UAS) and Unmanned Vehicle (UV) technology for road tunnel inspections.

“It’s a three-hour manual process, involving two workers walking along our underground (the MRT) tunnels for inspection. In the future, a drone zipping along the tunnel will be able to complete the mission in a much quicker and safer manner. Welcome to the world of technology and automation,” LTA said in a statement.

Participants of the RFI are invited to design and develop suitable trials based on UAS technology to conduct automated inspections in MRT tunnels. They can also develop trials involving UAS, UV or other technology for the inspection of road tunnels. The trials should incorporate 360-degree video mapping of the tunnels, as well as software to automatically detect defects from the video taken and provide their location.

Through the RFI, LTA will evaluate the feasibility and effectiveness of leveraging such technologies in the routine inspection of tunnels.

According to, manual inspections are currently carried out regularly on rail and road tunnels to detect anomalies, such as cracks or water leakage. LTA’s road tunnel inspections also cover rainwater storage tanks where utility lines are located. These checks allow LTA to ascertain the health of the tunnel structures so that necessary maintenance can be carried out. Such checks require workers to physically go through the tunnels. The inspection of rail tunnels is even more challenging as workers can only do so within a very limited number of hours at night, after passenger service ceases.

“The use of automated technologies such as UAS and UVs will not only improve the accuracy of inspections but will also free up engineers’ time, enabling them to focus on the analysis of the data captured to recommend any necessary remedial measures,” LTA said.

This RFI expands on LTA’s proof-of-concept trials at ten Thomson-East Coast Line sites, where UAS are being deployed to monitor work progress by taking aerial photographs and videos. These new trials will help to further current research developments and validate UAS and UV technologies under demanding operational conditions. If found effective, LTA aims to fully deploy these technologies for tunnel inspections in the next five years.