Staff Reporter

NEW DELHI: Boring a 1.775-km long tunnel in a single stretch, the Delhi Metro Rail Corporation completed construction work on its longest ever underground tunnel built by a single tunnel boring machine (TBM) at Khan Market here on Wednesday.

The DMRC claims the tunnel is the longest ever to be constructed by a single TBM in Delhi so far.

Till now two 1.45-km long tunnels constructed between Malviya Nagar and Hauz Khas were the longest made by TBMs.

Giving details of the breakthrough, DMRC spokesperson Anuj Dayal said: “Two major feats were achieved in the construction of the tunnel as it was completed in just 152 days. In another major achievement, 37.5 metres of tunnelling was completed in a day with the installation of 25 rings, which is an Asian record.”

Another 1.4-km long tunnel is set to breakthrough at Shivaji Stadium early next month on the Airport Express Line.

“The tunnelling work for this stretch was started on November 21, 2008. Another tunnel on the parallel line is expected to breakthrough in another month’s time. This tunnel is a part of the Central Secretariat-Khan Market stretch of the under-construction Central Secretariat-Badarpur corridor. This stretch of 2.53 km is actually the longest distance between any two stations under the Delhi Metro,” said Mr. Dayal.

As this is the longest underground stretch of the Delhi Metro without a station, a ventilation shaft is being constructed on Motilal Nehru Marg.

The main function of the shaft would be to provide ventilation and fire escape facilities. Two shafts will be constructed. While one will be used for fire escape, the other will be used for ventilation purposes.

All the tunnelling activities on the corridor are expected to be complete by August 2009, he said.