“The tunneling work started in February this year and we have completed it with the break-through of first of the two TBMs (tunnel boring machines). The second tunneling work is expected to be completed in a month’s time,” said Arvind Kumar Rai, Chief General Manager (Underground), CMRL.
The tunneling work, carried out by Afcons Infrastructure, happened at an average rate of 11 metres a day, which is significantly higher than average speed achieved in other stretches. The clay soil conditions were favourable for tunneling and led to the completion of works ahead of time. Rai also said the tunneling works were taken up beneath the railway tracks at Washermenpet besides crossing under 480 buildings and 310 borewells, of which 10 were open wells. “We kept monitoring triggers and impact during the tunneling works and no damage to the existing buildings was reported,” he added.
Alongside the tunneling, works related to building stations were also happening and about 30 per cent of the work for stations on the stretch has been completed. Signalling works are expected to start by the end of this year. The 1.82 km underground line is part of the 9 km extension project to have connectivity from Washermenpet to Wimco Nagar, which is expected to be operational in two years. The underground stretch will have two stations – Thegaraya College and Korukkupet and after which it will be an elevated corridor.
“The target is to complete both underground and elevated works by 2019 and we hope to complete on schedule within the project cost of ₹3770 crore,” said Rai. The phase 1 extension will seamlessly integrate with the Phase 1 corridor 1, thereby offering direct connectivity from Wimco Nagar (north Chennai) to Chennai airport (South Chennai) once underground and elevated portions of Phase 1 extension are completed.