It is more than six decades since planners first outlined a ring road for Glasgow that would provide access to the city and enable through traffic to avoid clogging its centre. Today, that ring road is a reality, with the exception of a five-mile missing link between the south-east outskirts and the M8 south of the River Clyde. The completion of the M74 has been delayed for decades by a combination of well-founded objections, lack of political will and bureaucratic paralysis. In the meantime, the case in favour has grown from desirable to overwhelming. In The Herald today, we report that Scottish Government ministers have a month to complete negotiations with the Interlink M74 consortium. The circumstances are not ideal. It is incumbent on ministers to get best value for the taxpayer. This is difficult when there is only one bidder, especially at a time when so much capacity in the UK construction industry is being absorbed by projects linked with the 2012 London Olympics. But any attempt to delay this project yet again must be resisted for several reasons. First, if the government were to put the project out to tender once more in the hope of attracting more bids, it runs the real risk of drawing a blank. Secondly, both construction jobs and the capacity to pay for them are only going to get tighter in coming years, thanks to inflation and the looming issues of a second Forth crossing and the 2014 Commonwealth Games. Thirdly, the reasons why Glasgow needs this road become more compelling all the time.

The challenge of keeping Glasgow moving gets tougher every year. The M8 stretch through the city centre has become one of Britain's worst bottlenecks. The Kingston Bridge, the busiest river crossing in Europe, is almost permanently clogged with crawling or stationary traffic. There are choke points on trunk roads throughout Glasgow's south and eastern flanks. The cost to the city and to Scotland in terms of frustration and lost productivity from this congestion is incalculable. Scotland's auditor, Robert Black, is among those who have said the M74 completion is necessary to avoid permanent gridlock.

The number of jobs likely to be created by any particular infrastructure investment is always a controversial subject. Some question whether 20,000 posts, the equivalent of close to one per foot, will be conjured up by five miles of motorway, as has been claimed. What we can say with certainty is that, without it, the east end of Glasgow will continue to struggle economically. Of course, some of the firms likely to be lured to Glasgow by easy motorway access may have gone elsewhere without it but this area is home to some of the most deprived communities in Britain and attempts to regnerate them have been hampered by poor infrastructure. The challenge of preparing for the Commonwealth Games adds an additional incentive to get cracking.

There is even an environmental case for the M74C, as it has become known. The conventional wisdom is that road-building merely encourages more people to use cars rather than public transport. But congestion is environmentally costly, too, as well as adding to the city's poor air quality.

Millions of pounds have already been spent on buying out businesses along the route. For years a broad swathe of land running through south-east Glasgow, much of it heavily contaminated, has been blighted by this project. The time has come to cut the cackle. The main trunk route from the border was never intended to end abruptly in the outskirts of Glasgow. This project has been idling in neutral for far too long.