Chennai Metro is a urban transport system in the city of Chennai, large fast developing city in the South of India. The system comprises 4 lines, part underground and part elevated, and a total of 42 stations. Construction started in 2009 with the first line opening to the public in 2015. Total length of the system planned exceeds 45.1km.

Underground stations For this large construction project, Dextra has been involved between 2011 and 2015 in the design, engineering and supply of 61 FRP Soft Eyes for stations entry/exit points as well as TBM insertion/extraction shafts.

Thanks to the properties of FRP material, Tunnel Boring Machines cut through the D-Wall in a minimum time, saving time on schedule and ensuring the perfect condition of the TBM’s head.

Elevated segments As a complement to Soft-Eyes for underground parts of the lines, Dextra also supplied Post-Tensioning Bar Systems for permanent applications.

The PT systems are connecting piles and precast segments of the elevated viaduct (shear key and hold-down applications). Each bar system, composed of high tensile performance bars, plates and nuts, is post-tensioned to provide seismic resistance.

For each of the 1,000 sets used on Chennai metro, Dextra also supplied the corrosion accessories necessary for this type of permanent applications.

D-Walls Finally, 350,000
Bartec couplers were also used vertically and horizontally in the station D-Walls.

Horizontal connections are performed with couplers left pending. Reconnection is done one the station is excavated, with second phase rebar being reconnected to start the slabs.