MRT Downtown Line is a 44-kilometers fully underground subway line connecting North West and Eastern areas of Singapore main island. With 36 stations, it should ultimately transport more than half a million passengers per day.

The construction of the line has been done by segments. Parts of the line are already operating. Full completion is planned by 2024.

Dextra has been involved since between 2008 and 2011 in the design, engineering and supply of large FRP Soft Eyes for multiple stations packages to the various contractors involved.

A total of 19 Soft-Eyes (2)have been engineered and produced by Dextra for the DTL line. The Soft-Eyes are part of station D-Walls and positioned at station entrance/exit of each station.

A total of 19 Soft-Eyes (2)have been engineered and produced by Dextra for the DTL line. The Soft-Eyes are part of station D-Walls and positioned at station entrance/exit of each station.

Prior to D-Wall construction, Dextra engineers the FRP cage design taking into account size of the TBM, margin for error, soil forces and more design parameters.

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.

In complement of Soft Eyes, Dextra also supplied various subway stations with Bartec rebar couplers.

In D-Walls, rebar coupler (2) are mostly used as a way to perform second stage rebar connection. Once the excavation completed, couplers are used to connect starter bar to the D-Wall in order to build the slabs.

(1)Soft Eye FRP reinforcement in D-Wall before lowering the cage.

(2)Pending rebar couplers for station slab connection.

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.