The project did not disturb the flow of M1 traffic

The work at junction 15A of the M1 is an unusual contender for the Better Public Building Award, competing alongside sites such as the refurbished Treasury building in Whitehall and other notable libraries and museums.

The 13 projects on the shortlist have all been selected for their "diversity and excellence".

The winner of the award - now in its third year - will be announced by Prime Minister Tony Blair in October.

It is not a gleaming building but it is an innovative solution Don Higgs, Edmund Nuttall

The £6m M1 project, on the outskirts of Northampton, involved inserting a concrete underpass for the A43, underneath the busy motorway.

An innovative tunnelling system was used to gradually insert the pre-fabricated concrete box section into position beneath the M1.

Over a four-week period it did not disturb the daily traffic of 120,000 vehicles which pass along the major route.

It would have been cheaper to close the motorway and dig out a trench, but at the cost of disruption and diversions for drivers.

The motorway construction will be up against competition from other, perhaps more visually impressive, nominees.

These include the Imperial War Museum of the North in Manchester, the Centre for Mathematical Studies in Cambridge, Bournemouth Library and the newly refurbished Treasury building in London.

But it has many of the right credentials for the award, which recognises "excellence in design quality and procurement practices of publicly-funded building schemes".

Tourist site

Project manager Don Higgs, from contractors Edmund Nuttall said: "It is not a gleaming building but it is an innovative solution that will be used by hundreds of motorists for years to come and which we built without disturbing a single motorist on the M1."

The concrete box had already become a tourist site, he told BBC Radio 4's Today programme.

Commenting on the shortlist, Tony Blair said the contenders should act as an inspiration to all public sector building work, which faces huge criticism when it fails while its successes are rarely acknowledged.

The refurbished Treasury building is also among the shortlist

The award, the winner of which will be announced in October, is sponsored by the Commission for Architecture and the Built Environment (CABE) and the Office of Government Commerce (OGC).

Sir Stuart Lipton, chairman of CABE, said the shortlisted schemes reflected the "diversity and excellence" to be found in the public sector.

"The question we now need to ask ourselves is why every new public building is not of the same high quality as this year's entrants," he added.

The final contenders were being formally announced at a reception at the Treasury on Wednesday.

They are: