The contract, which is expected to be worth between US$134 million and US$194 million, is the most significant single element in the Glasgow Airport Rail Link (GARL).

"I am delighted by the great progress already being made on GARL, which will be delivered well in advance of the Commonwealth Games in 2014 to help Scotland capture the long term economic growth the Games will bring," said transport minister Stewart Stevenson. "Through Transport Scotland, our continuing investment in major transport infrastructure projects is currently supporting hundreds of jobs in the Scottish construction industry.

"I am particularly pleased that seven major construction companies, either individually or in a consortium, are lining up to bid for this flagship public transport project in the West of Scotland."