The Delhi Metro is the largest and busiest rapid transit system in India, serving Delhi and its satellite cities of Ghaziabad, Faridabad, Gurgaon, Noida, Bahadurgarh and Ballabhgarh. It operates over 2,700 trips daily.

The system currently consists of 10 color-coded lines passing 253 stations with a total length of 348 km, including a mix of underground, at-grade, and elevated stations.

The development of the network was divided into phases. Phase 1 and Phase 2 were completed by 2006 and 2011, respectively. Phase 3 has 35 underground stations and 3 new lines, totaling 167 km, and is scheduled to be mostly completed by the end of 2020.

The total length of the underground corridors in Phase 3 is 54 km, more than 20 km longer than the total underground sections in Phases 1 and 2 combined, making it one of the most challenging construction phases.

More than 20 tunnel boring machines were used simultaneously to expedite the tunnel work through 10 Dextra soft-eyes installed in diaphragm walls. Thanks to the cuttable nature of GFRP (glass fiber reinforced polymer) bars, TBMs can get in or out of shafts/stations in few minutes.

Furthermore, 450 sets of active anchors were applied to retain walls during the excavation work. The anchors are also made of GFRP, hence the tendons can be excavated by any standard equipment, and no anchor removal is required.

Moreover, around 2.3 million Bartec couplers were installed to connect rebars in various parts of the concrete structures of the stations. Bartec is a bar-break performance system, designed to withstand an ultimate tensile performance of up to 800 MPa.

2,800 sets of Shear Key post-tensioning systems were also inserted into the concrete reservation as a permanent seismic restrainer for the connection of the elevated metro segments.

The Perth City Link is an transport and urban development project taking plate in Perth, Western Australia. It aims to reclaims more than 13.5 hectares of land previously used by connecting railways by sinking a train lane, hence making land available at the surface to reconnect two parts of the city with streets, commercial and residential buildings.

For this project, Dextra has been involved between 2012 and 2014 in the early foundation works:

• Supply of Dextra Rolltec mechanical rebar splicing solution, used for the vertical connection of rebar in D-Walls and Micropiles. Rebar couplers were used to reconnect cages which had been previously prefabricated by our rebar partner fabricator in Perth.
• Dextra also supplied its Sonitec sonic tubes used the Cross Sonic Logging (CSL) integrity testing of the foundations piles.

For more information about foundations solutions available in Australia, please consult our Bangkok office

Riyadh Metro is a massive urban transit system project under construction in Riyadh, Saudi Arabia. The project will feature 85 stations, built along 6 transit lines, for a total rail length of 176km. It is expected that the system will serve at least 1 million passengers daily at its inauguration in 2018.

For this large infrastructure project, Dextra has been involved on various stations and packages.

Excavation works

Before proceeding with general construction works, during early excavation phase, it is required to anchor retaining walls back into the stable ground in order to prevent any wall displacement. This will allow to keep excavating in a safe environment.

For that purpose, Dextra supplied steel ground anchors installed at the station perimeter. Each system is based on a high-tensile fully threaded bar, coming with nut and plate, and grouted to provide bonding with the soil.

For more information, please refer to Steel Ground Anchors page.

Raft & Vertical connections

Bartec rebar couplers were supplied for the works in the stations. Couplers were used for slabs, column and wall connections. A typicall application on this project is to cast rebar couplers in the concrete with reinforcement, and then proceed with second phase bar connection at a later stage.

Unitec bolted couplers can have also been use on various parts of the project. Typically Unitec is used when overlap is planned but lapping length appear to be too short to perform a safe splice. In that case Unitec provides a convenient and full performance connection.