CHENNAI: The second phase of the Metro rail project in Chennai at the cost of Rs 63,246 crore will commence in November. According to CMRL sources, this phase will cover a stretch of 118.9 kilometres.
Three pathways are expected to be created of which 77.3 kilometres would be made overground and 41.6 kilometres underground.
The pathway between Lighthouse - Poonamallee would be given special focus making it functional from June 2025. Overground works for the Poonamallee and Powerhouse routes are going on.
The 'rocky' issue:
While digging underground if the tunnel boring machine (TBM) hits a rocky surface, there could be delays in the work. This is because on average a TBM could dig up to 10-15 metres per day, but it reduces to a mere 4-5 metres if rocks are found underground.
This bottleneck is more likely to be faced in the Nathamuni-Retteri pathway that stretches up to 5.5 kilometres following the recently concluded soil test for this route and the Royapettah-Tiruvanmiyur route.
The CMRL sources said that of the numerous reasons for the tunnelling delay in Anna Salai the major was rocks.
Two pathways for arrival and departure would be made and a third one for connecting two locations.