Chennai: With only a month left for the onset of Northeast Monsoon, Chennai Metro Rail Limited (CMRL) will immediately start a maintenance work in an underground tunnel to identify and improve leakage and prevent water stagnation when it rains.
The Metro Rail Network in this city has a twin tunnel that covers almost 27 km which is associated with 21 metro stations in the phase-1 extension line and 9km phase-1 45km.
Officials said the engineer team would check the tunnel and identify areas and leakage points / seepage and install with grouting.
CMRL recently floated tenders to assign companies that would carry out good maintenance work in tunnels and underground stations.
“Grouting will involve a cement injection to the surface of the tunnel to plug in the gap that might be a source of water seepage,” said an official.
While grouting was carried out during the construction of the tunnel, officials said the tunnel and underground stations require periodic maintenance to plug in any leak because they were built through groundwater tables.
While the tunnel is designed and built to allow a number of water seepage from the water table drained through the system installed under the track, excess water leakage can affect train operations during the rainy season.
Furthermore, a month ago there was a report that the tunnel between the Washermenpet and Tondiamanpet Station, which was opened for services in February 2021, had witnessed a leak.
Officials said one reason for water seepage was a high level of water table in these areas.
Likewise, leaky water from the roof has become a long-delayed problem in underground stations such as LIC, Nandanam which is located in the artery of Anna Salai especially during the rainy season.
When rainwater stagnant on the road, the roof of the station began to leak and passengers were forced to walk in the pool of water on the station floor.
Last year, part of the thousands of metro station lights was hit after the roof close to one of the entry points began to leak due to the broken metrowater pipe.
Engineers will also do work on high structures to detect and improve defects or failures which can ultimately affect the safety of increased bridges and stations.