The Interlink consortium of Balfour Beatty, Morgan Est, Morrison Construction and Sir Robert McAlpine are expected to open the 5 mile stretch of road well ahead of its February 2012 deadline.

Despite the record cold spell in winter, progress on the £445m M74 extension has been consistently ahead of schedule, with all the major structures in place by July.

In total, around £645m will have been spent on the road by the time of its completion, including £200m for land purchases and preparatory works, plus a possible £12m contingency to allow for mine workings along the route.

The route runs from Fullarton junction, near Carmyle, to the M8 just west of the Kingston Bridge, passing over some of the most contaminated and polluted parts of Scotland to transform urban wasteland into business and residential areas.

Completion of the route will significantly reduce congestion on the busiest stretch of the M8 through Glasgow and provide a major economic boost to west Scotland.

The motorway project is one of a number of major ongoing investments in transport infrastructure around Glasgow.

Others include the £300m Airdrie-Bathgate rail link, due to open in December; a £320m upgrade to the M80 between Glasgow and Stirling and as a £1bn programme of rail investments scheduled to begin in earnest next year.

Scottish Government finance secretary John Swinney hailed the early completion as a testament to the whole project team’s excellent stewardship of a complex scheme involving many challenging civil engineering operations”.

He added: “When it opens next June, the new route will provide improved access to economic, employment and education opportunities for the people of Scotland.

“It will also bring enormous potential for further urban regeneration programmes in the west of Scotland, many of which are already in development.