A traffic-free horizon over the 4,000 year old Stonehenge monument is set to conclude a decade of wrangling over how to divert the A303 away from the stones.
Consultant Mott MacDonald has been appointed by the Highways Agency to create designs to divert the busy stream of polluting traffic on the A303 underneath Salisbury Plain via a 2km cut and cover road tunnel.
The estimated £130M solution, developed with the Government and environmental and local stakeholders such as English Heritage, is designed to ease congestion and boost patronage of a brand new visitor centre planned at nearby Amesbury.
Highways Agency project manager Edmund Bradley explains the need for the project: 'Many people slow down to take a look as they drive past the stones, often causing accidents and adding to bottlenecks, ' he says.
'Drivers also carry on, without really experiencing the site as a whole - or paying.'
The proposed 10.8km preferred A303 route announced last year and expected to start construction in 2005 has already been promised funding from the Treasury and Heritage sources.
Bradley says: 'The cost/benefit ratio of the scheme suits the Treasury's guidelines. Together with the Agency, they are providing two-thirds of the total cost. The rest of the cost is being picked up by heritage sources.'
But Mott Macdonald project manager Stuart Bromley says many decisions on the financing and procurement have still to be made: 'The option of early contractor involvement in the scheme is being given serious consideration, with a view to improving buildability at the planning stage.
'Hopefully we should be able to minimise duplication of design, and get value for money.'
'We still haven't ruled out PFI, ' Bradley adds. 'And no decision has been made on procurement methods for the scheme, although we are likely to consider early and conventional design and build options.'
Critics of the scheme are unhappy that £40M of the Government funding is planned to come from Lottery money.
In 1999 the Heritage Lottery Fund decided to shake up its system of cash handouts, by keeping aside £75M per year for the next three years for one off payments to larger 'beacon' schemes regardless of location.
Stonehenge was one such beacon project, argues Sir Jocelyn Stevens, recently retired chairman of English Heritage. 'Without the Lottery contribution we could not have raised the money, ' he said at an ICE debate on the subject in 1998. Critics view lottery funding as 'expedient' and 'the thin edge of a thick wedge'.
Environmentalists have also argued for a more expensive bored tunnel under the stones because a cut and cover tunnel would ruin untouched burial mounds.
A spokesman for Transport 2000 said: 'There are a number of burial mounds along the proposed route that are yet to be investigated. A cut and cover tunnel would destroy them forever.
'There are also concerns that the cut and cover process would lead to irreparable scarring of the landscape.'
The Highways Agency disputes these claims, stressing that the cut and cover option is the only way forward.
'The bored option would add a further £40M to the price tag, ' says Ed Bradley. 'We realise that the landscaping and archaeology are of utmost importance, which is why we have specialist landscapers on board - Nicholas Pearson Associates - and archaeological advice from Wessex Archaeology.'
English Heritage also disputed the wisdom of a bored option in a letter to the Times by Sir Jocelyn Stevens.
'Even if the bored tunnel was affordable it would have its own negative impacts; ventilation shafts along its length, the noise of fans audible above ground, deeper portals which could result in greater damage to the landscape and archaeology, and possible long term effects on local aquifers, ' he wrote.
'Nobody claims there is an ideal solution to the problems facing the World Heritage site. But we believe our plan is the best way forward.'
Topological and ground investigation surveys for the cut and cover tunnel from Mott MacDonald are planned or about to start. Archaeology and landscape assessments are also to be carried out in greater depth.
'The overall aim is to develop the surveys, co-ordinate all parties and publish draft orders in 2002, ' explains Bradley.
Following draft orders, the scheme will be subject to further consultation leading to a public inquiry if objections are not resolved.
One vociferous objector to the current plans is local engineer Graham Parker, who has suggested an alternative bypass route that totally avoids the heritage site.
'My route could also incorporate the proposed bypass for Salisbury thus providing savings for the taxpayer.' he argues.
But the Agency is preparing to face all comers.
'We've included a reasonable amount of time for a public inquiry in our programme, ' says Bromley, adding that is it 'highly likely' that an inquiry will be necessary.
Construction is expected to be complete by 2008.