Safety first inside Metro tunnel

For the first time in South India, a Metro train will make a commercial run through an underground stretch on Friday.

In eight minutes flat, as Namma Metro’s east-west corridor train completes that 4.8km stretch, commuters might harbour a nagging thought: what if the train stops suddenly inside the tunnel. Is it safe enough?

To banish that thought, a team from Deccan Herald went underground checking out all the safety measures in place. Tunnel-walking from the Cubbon Park station till the Vidhana Soudha stop 400 metres away, the team noticed a walkway at a three-metre elevation from the track. Attached to the tunnel wall on one side, it ran the full distance between the stations. The walkway had a clear purpose: quick evacuation.

But what about the air? The Metro engineers were sure, the air-conditioning within the coaches would suffice to keep everyone inside comfortable for 20 to 30 minutes. Once the commuters get onto the walkway, the Tunnel Ventilation System (TVS) will do the trick.

Simply put, the TVS is about blowing air into the tunnel from one station and taking it out from the next one continuously. This keeps pure air, collected from outside, in regular circulation inside the entire underground stretch.

This atmospheric control is required also for smooth train movement. The tunnels are equipped with 24/7 lighting to ensure that any safety operation and track maintenance are problem-free.

This is critical, as at any given time, 14 trains will be running on the tracks, seven on either side. This number could rise if Bangalore Metro Rail Corporation chooses to increase the frequency from the current 10 minutes to a train every three or five minutes. Once the entire first phase is completed, 29 trains will run on the green line and 21 on the purple line.

The tunnel, with 5.6m inner diameter and 6.3m outer diameter, opens into each underground station at a height of about 60ft. The Environmental Control System regulates the air within. As the Deccan Herald team approached the station from the tunnel, a Rail Grinding Machine was busy smoothening the tracks. Its driver was working on a tight schedule. For, the line had to be in shipshape by 6 pm on April 29, the moment chosen for Bengaluru’s tryst with its first tunnel train run.