Excavation for Dubai Metro’s Red Line got underway at the end of January with the Mitsubishi EPB machine starting to bore a 1.45km tube from Union Square station towards Burjuman station.

Passing under a creek with about 10m-13m cover to the bed, the TBM will bore at 22m below sea level. The ground is characterised as marine sand over cemented sand and sandstone with a high water table, typically 3m-4m.

The excavated diameter is 9.59m, and the bolted segmental lining with ring taper will employ hydrophilic gaskets and external corrosion protection. The scraper-tooled TBM is 10.7m long, weighs 820 tonnes and the entire tunnelling train is 82m long.

The metro line is being built by Dubai Rapid Link (DURL) consortium, which was awarded the contract in 2005 by client the Roads & Transport Authority (RTA) for the lowest bid of US$3.39bn. The consortium includes Japanese groups Mitsubishi, Obayashi and Kajima along with Yapi Merkezi of Turkey (T&TI, July 2005, p7). Tunnel designer is Atkins.

Construction of the Dubai Metro, which in the early stages has two main lines – Red and Green – is approximately 30% complete and is running to schedule, according to RTA. DURL was recently awarded contract to build the Green Line, which was an option under the original contract.

The Red route will have four underground stations, the Green Line six, and both Union Square and Burjuman will be key interchanges. The total length of single bore, twin track tunnels to be created is 9.7km, linking the underground stations of both lines in a loop at the creek.

At about 75km long when fully built, the Red and Green lines will have 47 stations and be one of the longest driverless train systems in the world. The 52km long Red Line is to commence service in September 2009, the 23km long Green Line in March 2010.