The ancient market town of Baldock has been a traffic hotspot for millennia. Archaeological investigations have uncovered traces of roads dating back to the Bronze Age.
More recently, the Great North Road (A1) and the busy A505 linking Luton and Cambridge intersected in the town centre.
The problem was first tackled by local authority planners in the 1950s, who sketched out an ambitious design involving two bypasses. One, to the west, was eventually built in 1968 as the A1(M). But more than 22,000 vehicles a day still grind through Baldock's narrow streets.
'There was a lot of public consultation during the 1970s and 1980s, and the first public inquiry was held in 1995, ' explains client Hertfordshire County Council project manager Barry Anderson.
'It had to decide between a northern or a south eastern route. Problems with forming a junction on the A1(M) meant that the only realistic option was the south eastern route.' But this choice had its own problems. It cut through the Weston Hills, described as 'Baldock's lungs'. 'A 'Twyford Down'-style huge notch through the chalk just wasn't acceptable, ' Anderson reports. Another public inquiry in 1999 insisted on a tunnel through the most sensitive areas of the hills, a decision that would have a major impact on the procurement of the project.
'This made it a very expensive project for a county council, ' says Anderson. 'And by this time the government was very keen on PFI. We spent three fruitless years in a quest for a good deal, but the package was simply too expensive for the actual length of new road involved. This was because of the tunnel.' Eventually the government acknowledged that the new bypass was a strategic link, connecting the A1(M) to the M11. Funding became available from the Government Office for the East of England. Hopes were high that construction could begin in 2002 - but then another snag cropped up.
Anderson explains: 'The indicative design prepared by the council's highways department was now eight years old. Standards had changed, environmental considerations had become tighter. And the tunnel design in particular still needed a lot of development.' Other recent bypass projects in East Anglia have been complicated by the presence of great crested newts. Further to the west, on the dryer environment of chalk hills, the Baldock Bypass's particular beastie was the not-so-common common lizard. Translocating the lizards and dealing with badger setts could have led to even further delays.
'We didn't want to miss the 2004 muckshifting season as well, which looked likely with most forms of procurement, ' Anderson says. 'Local expectations were that once we got the money work would start straight away.
'The only way of achieving this was to go down the design and build route.' An updated illustrative design was prepared by Hertfordshire's term consultant Mouchel Parkman. The contract was put out to tender in mid 2003, and in February 2004 a £47M bid from a joint venture of Norwest Holst and Capita Symonds was accepted.
The cut and cover option for the Weston Hills tunnel had been preferred almost since the project was conceived, Anderson reports. 'And the final alignment of the entire bypass is no more than 20mm away from the 1995 design, ' he adds. There have been some major changes in the rest of the structures, which largely feature integral steel/concrete composite construction.
Much of the bypass is in cutting. More than 1.5Mm 3 of chalk will have to be shifted over the course of construction, nearly all of it remaining on site in embankments, and landscaped noise-reducing bunds along the line of the new road. In 2004 Norwest Holst achieved a total muckshift of 1Mm 3, most of it from the Weston Hills. By August the tunnel foundations were under construction.
By this time, other things had changed as well. Under current legislation any tunnel more than 150m long has to have special safety features.
Anderson explains: 'Our tunnel, the only one on the county's road network, is 240m long.
This means fire resistant plastic fibres in the concrete as well as escape doors between the bores. And there has to be closed circuit television 24 hour monitoring.
'Originally we assumed this would be added to Hertfordshire Police's existing network of trunk road CCTV cameras. But the Highways Agency has now taken over all such networks - and is quite adamant that it won't accept responsibility for monitoring county roads.' In the end the local police agreed to monitor the tunnel.
Construction is now advancing rapidly despite the inevitable loss of time over the festive season. And somewhere close by 60 translocated common lizards are snoozing away the winter in safety.