INDIA’s National High-Speed Rail Corporation (NHSRCL) signed a contract worth Rs 64bn ($US 776m) with Afcons Infrastructure on June 8, covering the construction of the 21km section of the Mumbai - Ahmadabad high-speed line running in tunnel from Bandra Kurla Complex in Mumbai to Shilphata.

Work is expected to begin shortly, and includes 7km of undersea tunnel. Under the terms of the contract work must be completed within 1888 days.

Technical bids for this ambitious contract were opened on February 9, followed by financial bids on April 6. Larsen & Tubro also submitted a bid for the contract.

Three tunnel boring machines (TBMs) with a cutter head diameter of 13.1m will be used to excavate 16km of the single-bore tunnel which will accommodate both tracks of the high-speed line.

“The New Austrian Tunnelling Method (NATM) will also be used,” says NHSRCL managing director, Mr Rajendra Prasad, with the remaining 5km of Bandra Kurla Complex - Shilphata section of the high-speed line to be built using NATM.

Underground rail tunnels in India usually have an internal diameter of 5.5m, but the new tunnel in Mumbai has a greater diameter to mitigate the build-up of air pressure waves caused by high-speed operations.

The tunnel will be built at depths ranging from 25m to 65m below ground level, and three shafts will be built at Bandra Kurla Complex, Vikhroli and Sawli to provide access to worksites. An inclined shaft 42m in length at Ghansoli and a tunnel portal at Shilphata will be built to provide access for construction machinery to excavate the 5km NATM section.

The contract also includes the construction of 39 equipment rooms at 37 locations adjacent to the tunnel.

Afcons Infrastructure is based in Mumbai and recently completed construction of a 5.55m diameter tunnel under the Hooghly River for the East-West Corridor of the Kolkata Metro.

The civil works contractor has also been engaged in the construction of the Chenab Bridge on the Uddhampur - Srinagar - Baramulla Rail Line (USBRL), which with a deck height of 359m has been described as the world’s highest railway bridge.

Following a change of political leadership in Maharashtra in July 2022, work in this state to build the Mumbai - Ahmadabad high-speed line has made significant progress.

The contract to build the high-speed station in Mumbai was signed in March, while work has been progressing on the construction of other stations at Thane, Virar and Boisar.

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