Consortiums bidding for Qatar Railways Company (QRail) civil projects will need more information about the conditions of the soil through which 49 kilometres of twin-tunnels required to deliver phase 1 of the Doha Metro will pass, the MEED Middle East Tunnelling 2011 was conference told this morning.
Speakers said potential bidders for tunnel projects did not have sufficient information upon which to base a risk-adjusted bid to take into account ground conditions.
“Geotechnical investigation is very critical,” said Sally Vest, senior project geologist at Halcrow.
The first request for proposal (RFP) for one of the 15 projects in phase 1 is due to be issued in the second quarter of 2012.
Disposing of waste will also be a challenge for the consortia undertaking tunnelling work on the QRail programme.
“It is not so much what is in the ground,” said Parsons senior vice-president Steve Minassian. “It is the additives that go into the slurry to make the TBMs [tunnel boring machines].”
Speakers said that dealing with subsurface water would be one of the biggest challenges facing the TBMs to be used in the QRail civil programme. QRail says it expects up to 20 TBMs to be used at any one time on phase 1 projects.
Fernando Fajardo of Acciona Infrastructuras said different TBMs will be needed for different plots and contracts.