Double Decker Line & Station standing in single pillar is planned in Phase 2 of CMRL Project : Thiru. T. Archunan

CHENNAI (Metro Rail News): Chennai Metro Rail Limited has commenced the expansion of Chennai city’s metro rail network as a part of Phase II after the successful completion of Phase I and Phase I Extension Corridors in stages since June 2015 and the growing ridership in Corridors 1&2.
Now, CMRL has ventured into extensive infrastructure development in the city, comprising three more metro rail corridors for a total length of 118.9 km & 128 nos of stations being funded by several multi-national funding agencies, including the JICA, ADB and AIIB.
The Salient & Unique features of Phase II
Elevated Section
CMRL will have a Double-decker line & station standing in a single pillar for a stretch of about 5 km. The double-decker stretch will have four stations developed at two levels; Alwarthirunagar, Valasaravakkam, Karambakkam and Alapakkam will have a common concourse (ticketing level) with two different platforms. To execute the same, a special Launching Girder is fabricated and ready for use.
Many Balanced Cantilever method spans are adopted as great spans to suit the site conditions. Out of all, the most challenging location is Kathipara Junction. 5 spans continuous BCM (1 x 58m + 3 x 100m + 1 x 95m) with a 125m radius curve. Integrating with State Highway flyover at Thoraipakkam, Sholinganallur, Kattupakkam, Majambakkam & MIOT flyover location.
Underground Section
Stacked station: CMRL has planned to go with underground stations with a stacked-up platform design at locations where the width of the roads is as narrow as 10m. Pattalam, Thirumayilai, Kutchery, Alwarpet, and Bhardhidhasan road stations have staked tunnels.
Intersection of Tunnel: At Kilpauk, Thousand light and Nandanam, Phase II tunnels pass below the Phase I running tunnels. More challenging to execute the same.
Crossing of Adyar River: Corridor 3 crosses Adyar River near Adyar Junction (UG). The Crown of the Tunnel is 7 m below the bed level.
Multi-Modal Integration will integrate the Phase-II Network with other public transport modes, namely Suburban Rail, MRTS, City Bus Service, etc., at 21 different locations to ensure hassle-free and seamless connectivity.