A plan by BAA to roll a new air control tower down a runway from one part of Heathrow to another in an overnight operation has triggered alarm at Britain's busiest airport.
The vast 860 tonne structure is to be loaded on a specially made 64-wheel trolley but critics fear the move will not be completed in time to open the network again by 6am.
With six extra tunnels being built to provide links with Terminal 5, pilots and air traffic controllers have also expressed concern that the tower might weigh too much and literally disappear into the ground.
There have been previous tunnel problems at Heathrow. Balfour Beatty was fined £1.2m for a collapse 10 years ago which put lives at risk and caused the cancellation of hundreds of flights. It caused a huge crater to appear between the two main runways and damaged buildings.
But BAA insists its latest operation - expected to go ahead in November - will not cause any such problems. "Transportation of the 30-metre high cab has been carefully planned by an expert team and all safety considerations have been taken full account of," said a BAA spokesman.
"We have no concerns that the route of the cab's move across Heathrow's airfield is unsafe," he added.
The procedure has been planned by consultants for more than a year and the operation will be undertaken by the same firm which has already successfully transported large bridge structures across Gatwick and Heathrow, said BAA. "While the combined weight of the new tower cab and transporter is heavier than a typical jumbo aircraft, the impact on the airfield is substantially less because weight is spread across a significantly larger number of wheels."
The tower will eventually take over air traffic control for all of Heathrow, including the £4bn extension opening in 2008.
