Transport minister Stewart Stevenson said he was satisfied that government procedures were "robust" in drawing up the deal to build the M74 extension, after a recent complaint that the procurement process did not follow Euro rules.
A review of the process was necessary because the European Commission was asked to investigate the five-mile scheme after four potential bidders tendered for the work as a single consortium, and ministers combined two contracts into one.
Interlink M74, a consortium of Balfour Beatty, Morgan Est, Morrison Construction and Sir Robert McAlpine, is the sole bidder.
A tender price bid of £445 million, which is a fixed price, has been agreed with the Interlink M74 consortium, it was announced today, along with about £12 million for possible treatment of mine workings along the way.
Work is now expected to get under way on the scheme in May and finish in 2011.