There is an easier, safer and cheaper option to inspect rail tunnels (LTA considering using drones to inspect tunnels; March 2).
A machine or robot could be designed to glide on the rails, using the existing power supply or on-board batteries, as size and weight are not real constraints on the design.
It could have multiple cameras on adjustable arms that can take videos of the underside of rails and other less visible areas that require checking. The videos could be beamed back in real time or stored and checked later.
The robotic arms could be controlled remotely if something amiss is detected.
Drones, on the other hand, need to be "flown" remotely, and the payload is limited. They also work on batteries only.
If a drone were to crash in the tunnels, technicians would have to be despatched, and this could then delay the start of train operations.
The Land Transport Authority should reconsider its decision and spend the money and time on a request for information for rail-guided inspection machines rather than drones.
Chua Cheok Kwang