Chennai: Chennai Metro Rail Ltd on Wednesday achieved its 24th tunnel boring machine breakthrough in the Phase II project, with ‘Nilagiri’ completing tunnelling on the 819m up-line section between Madhavaram High Road and Moolakadai stations.This is the 11th breakthrough on the 9km underground section between Madhavaram Milk Colony and Kellys on Corridor 3, being executed by Tata Projects.The machine had to pass beneath Buckingham Canal, a busy traffic corridor and 14 borewells along the alignment, making it one of the most challenging stretches under the contract, said CMRL. Alternative water sources were provided during construction, while continuous instrumentation and monitoring ensured that ground settlement remained within permissible limits. Seven tunnel boring machines (TBM) have been deployed for the section between Madhavaram Milk Colony and Kellys.The breakthrough comes as CMRL accelerates work on the 118.9km Phase II project, estimated to cost ₹63,246 crore, across Corridor 3 (Madhavaram Milk Colony-SIPCOT), Corridor 4 (Lighthouse-Poonamallee Bypass) and Corridor 5 (Madhavaram Milk Colony-Sholinganallur). About 42km of the network is underground with 45 stations.The first operational stretch of Phase II, the 14.64km Poonamallee Bypass-Vadapalani corridor with 11 elevated stations, has completed mandatory safety clearances and is awaiting an inauguration date from Centre.Earlier, finance minister Marie Wilson, while presenting the state budget, said the Poonamallee Bypass-Vadapalani stretch would be opened shortly.
