In April 2004 the UK Highways Agency appointed contractor Nuttall and consultant Capita Symonds to work on two Early Contractor Involvement (ECI) projects between Cambridge and Bedford worth a combined $201M.
In effect, it created one project design team with two teams on site. The approach has meant that both are likely to finish well ahead of schedule.
The $102.6M A421 Great Barford Bypass, north east of Bedford, was the first project the design team worked on.
It immediately set about revising plans submitted to the public inquiry, starting with the over bridges.
'The proposal was that they would be in situ concrete bridges, ' says Nuttall project manager Simon Whalley.
'As part of the ECI and because of Nuttall's previous experience of working with Capita Symonds, we opted for a much simpler approach using a steel composite with lot of precast concrete elements.' Work began on site in October 2004 and will be completed ahead of schedule in August.
The second scheme is the $99M A428 Caxton Common to Hardwick improvement. It is now following on and will benefit from lessons learned at Great Barford, says Nuttall project manager Adrian Savoury.
The project will transform 7.7km of the A428 to dual carriageway between Caxton, east of Bedford, and Hardwick, west of Cambridge and will accommodate the predicted rise in traffic between the new town of Cambourne and Cambridge.
Using the same design team as Great Barford, Savoury says that while the team worked on the bypass first, Caxton was always under consideration.
'We were all sitting there thinking about both schemes at the same time, ' he says.
This, for example, meant that Caxton is also using steel composite over bridges and that, because of the two sites' proximity, a lot was known about Caxton's geology very early on.
One section of the Caxton scheme that benefited both from ECI and the relationships established by Great Barford was the underpass at Hardwick Junction (see diagram).
The underpass is an 8m deep open excavation and the Agency envisaged that the contractor would build a diversion before digging under Scotland Road, the main road into Hardwick.
But this meant Nuttall redirecting telephone lines, power cables and a water main that runs along Scotland road.
Savoury and his team worked on a way of avoiding all this work and came up with a solution that reduces the underpass's width by building a single - rather than dual - carriageway on piled foundations, shifting the northern roundabout 25m west.
'We have then got the bridge off of the footprint of the existing road, ' says Savoury. 'This allows us to leave the traffic on Scotland Road.
'We can then build the deck, divert the traffic onto the new road and take out Scotland road.' Savoury says that this will save the project time and money, finishing a month or two ahead of its autumn 2007 completion deadline.