Union urban development ministry secretary Sudhir Krishna launched the tunnel boring work on Saturday. The Nehru Park–Egmore stretch lies on the Chennai Central- St Thomas Mount corridor. The contract for construction of twin tunnels on the stretch, including three underground stations at Nehru Park, Kilpauk Medical College and Pachiappa’s College, was awarded to Larsen & Toubro, which is in a joint venture with Shanghai Urban Construction Group (SUCG). They have completed 20-metre deep underground shafts to install the machines. The boring machines were lowered into a pit with supporting walls and a one metre-thick basement slab which will bear the machine as it drills forward.
As the boring machines function mostly on automatic mode, more than 100 engineers and system experts will be monitoring its work progress at a control centre.
Sophisticated machines are being used on the sidelines to check vibrations in nearby buildings.