TfL are in dicussions with a preferred bidder for the £40m contract

Transport for London has chosen a preferred bidder for the controversial London Cable Car project.

Industry sources have tipped Mace to win the contract, worth £40m, to build an aerial crossing over the Thames in east London.

However, a spokesperson for TfL refused to confirm whether Mace had been appointed.

It said: “We are in discussions with a preferred bidder that has been selected for the construction of the cable car but, as is normal practice, this information remains commercially confidential until legal agreements have been signed.”

When contacted by Building, a spokesperson for Mace said that it could not confirm the information as “discussions were ongoing.”

It is believed Costain and Vinci were also in contention for the contract. However, while Vinci is understood to no longer be in the running, it is thought that Costain could still have a lesser role on the project.

The cable car crossing will link the O2 Arena in Greenwich with the Excel centre in the Royal Docks. Cable cars will run 164ft (50m) above the river and carry 2,500 people every hour.

London mayor Boris Johnson has said views from the cable cars will be “some of the most spectacular in the capital”.

The project has drawn criticism because of escalating costs and delays that mean it will not be ready for the 2012 Olympics, as originally envisaged.

The project was delayed due to concerns the 1,100m-long structure would cross the “public safety zone” of London City Airport.

A study by the UK air traffic safety body, however, found that the probability of an aircraft accident affecting the crossing would be “less than one incident every 15 million years.”

Construction is scheduled to last two years with on-site work set to commence in early 2012.