Indian Railways builds longest electrified tunnel in record time! Key features of this game-changing project.

Another big record by Indian Railways! The South Central Railway zone has successfully commissioned the longest electrified tunnel. The 6.6 km long tunnel is situated between Cherlopalli and Rapuru railway stations and is part of the new Obulavaripalli-Venkatachalam railway line. On 25 June 2019, two freight trains successfully ran between the two stations, marking the full-scale operation of the newly built electrified line, thereby opening up viable railway connectivity between Krishnapatnam Port and its hinterland areas for freight train services. The tunnel has been completed in a record time of 43 months, enabling Indian Railways to start freight operations on this crucial line, which has reduced the distance between Krishnapatnam Port and its hinterland areas by 60 km.

At present, a goods train takes an average time of 10 hours to travel from Krishnapatnam Port to Obulavaripalli. On the newly electrified line, the travel time gets reduced to about 5 hours, thereby resulting in a saving of travel time by 5 hours. The tunnel is a game changer in the freight operations of the zone. It has paved the way to operate freight trains in Obulavaripalli-Venkatachalam-Krishnapatnam Port line for a distance of 113 Km. Now, the section is notified for commercial freight operations as well. Take a look at some of the salient features of the tunnel:

• The tunnel located between Cherlopalli and Rapuru railway stations has been constructed in shape of ‘Horse Shoe’.


• For the construction, New Australian Tunneling Method (NATM) has been used and a cost Rs 460 crore has been incurred


• The tunnel is in straight alignment and is 6,660 metres long.


• The height of the tunnel is 6.5 metres. While the minimum height of the contact wire is maintained at 5.2 metres.


• Ballastless track has been constructed with Bi-block sleepers and Vaslo fittings.


• The full-length lining has been provided with 300 mm thickness.


• Two traction power supply substations have been provided near Cherlopalli and near Adurupalli with necessary switching railway stations in between.


• OHE maintenance depot has been set up at Rapuru along with tower-car shed.


• Inside the tunnel, LED lighting has been provided at 10 metre intervals.


• Conventional OHE with a maximum span of 36 metres and maximum tension length of 1,206 metres has been provided. To support OHE, brackets have been fixed on wall mounted type plate fittings, which are attached to the tunnel lining concrete.


• For the first time in South Central Railway, instead of conventional type Auto Tensioning Device (ATD), Spring type ATD of South Korea has been adopted for maintaining necessary tension in OHE wires.


• For the safety of personnel working in the tunnel, fail-safe earthing arrangements were provided.

THE FINANCIAL EXPRESS