Metro tunnelling works to be finished ahead of schedule

CMRL officials told DT Next that the second 2 km-long tunnel from Washermanpet to Korukkupet would achieve wall-breakthrough in a week. 

The tunnel would be completed four months ahead of schedule, similar to the first one, which was completed on September 24, against the scheduled February 2018 deadline. On the 9 km Washermanpet – Wimco Nagar route implemented at an estimated cost of Rs 3,770 crore, the two-kilometre stretch till Korukkupet comprising three stations would be underground and the rest elevated. 

CMRL officials have attributed the swift pace of work to the nature of terrain, which was mostly clay and easy to bore. Metro has been consistently covering 11 metres per day on the section, the highest by its standards considering that it had struggled to clock a little over a half of it on May Day Park – DMS section, where the terrain was mostly rocky. 

The Herrenknecht tunnel boring machine (TBM) that dug from Washermanpet to Korukkupet had to cross railway tracks at Washermanpet with active rail traffic and cross under 480 buildings and 310 wells, including 10 open wells. Meanwhile, works of the stations on the route has progressed with the contractors completing over 30 per cent of them thus far. 

Notably, it was the terrain that had even delayed works on Anna Salai Metro route after Russian firm Mosmetrostroy abruptly halted the work owing to the tough terrain. Subsequently, CMRL had awarded the work to second contractor Afcons India limited, which achieved breakthrough early this month on the first tunnel from Government Estate to AG-DMS. 

The nature of the terrain was experienced personally by CMRL and even state industries minister M C Sampath after the already hard-hit cutters went blunt in the last 10cms and forced CMRL officials to wait 30 hours beyond the schedule to achieve wall breakthrough. Metro officers said the second tunnel from Government Estate to AG-DMS would be completed by the end of November.