Guwahati: The Northeast Frontier Railway has started using drones for detailed inspection of its bridges.

An NF Railway official said the drone-mounted inspection takes care of limitations like access to remotely located parts and components and safety of inspecting personnel.

"Bridge inspection is done following a detailed checklist. There have been limitations like accessibility to remotely located parts and components and concern for safety of the inspecting personnel as the inspection has to be carried out under running traffic. Both these limitations have been taken care of by the drone-mounted inspection. The cameras have given details of condition of steel members, rivets, welds and bearing conditions," the official said.

Given the kind of terrain that the railway operates in, there are a large number of bridges in the zone, many of them unique in dimension and specification, he added.

He said drone-mounted cameras, which cost anything between Rs 1 lakh and Rs 4 lakh depending on the bridge's size and location, would facilitate a detailed view of the bridge, its superstructure and substructure.

Survey of two major bridges on Guwahati-Lumding section by using drone has been successfully completed, the official said.

"Inspection of 28 important bridges are to be done by drone-mounted cameras. This includes the Saraighat bridge, the Naranarayan Setu and the Dayang bridge of Lumding-Badarpur hill section," he added.

The NF Railways has started under-water inspection of major and important bridges in which experienced divers use special equipment to assess the condition of bridge foundations.