Sacred stones tunnel debate1 March 2004
On 17 February, what promises to be a fiercely contested public inquiry opened in Salisbury, UK, into a road improvement scheme that proposes a 2.1km long twin bore tunnel past the ancient standing stones of Stonehenge.
The inquiry is scheduled to last until 30 April and is set to feature representatives from English Heritage (EH) and the National Trust (NT), the Highways Agency (HA), the Council for British Archaeology (CBA), the Campaign to Protect Rural England (CPRE) and the British Druid Order, among others.
Partners in the Stonehenge Project, EH and NT, will be thrust against each other due to their opposing stances on the tunnel length. EH holds the site of the stones in trust for the nation and said in a statement that it supported the Highways Agency's current 2.1km long proposal. The NT owns much of the surrounding land and advocates a much longer 4-5km tunnel to keep the portals away from archaeologically and visually sensitive ridgelines. Martyn Heighton, territory director for the NT said: "We cannot sell Stonehenge short."
Various alternatives will be considered during the inquiry, but the NT does not formally promote any of them, saying its objections to the proposed scheme are "not in relation to economics or highway engineering".
The Stonehenge scheme has been previously assessed in a report by Parliament as part of a country wide tunnelling review and it was noted that the Department of Transport (DoT) cost benefit appraisal scheme to evaluate projects would generally favour surface over tunnel options.
During the inquiry a representative of Halcrow, who is involved in the current scheme's design, stated the tunnel option gave "marginal value for money, when considered purely in terms of transport benefits" but emphasised that environmental benefits should also be considered. Jonathan Startin, also of Halcrow said a "bored tunnel [was] selected on the basis that it would disturb less land in the World Heritage Site than the cut and cover proposals".
He went on to describe that the proposed 10.5m diameter tunnels would be constructed using NATM techniques with a primary sprayed concrete lining and a secondary concrete lining separated by a waterproof membrane. Cross passages are planned for emergency evacuation, plus three plant rooms and a sump as well as a central service tunnel.
Startin said the significant initial cost of the service tunnel would be offset by the reduction in size of the main bores and reduced long term tunnel maintenance costs. He added that annual operating costs were estimated at US$2.4M for the tunnel.
If approved, tunnelling could start in mid 2005, with work ongoing until 2008. The tunnel is costed at US$351M with US$128M to be funded by the Department for Culture, Media and Sport.
Charles Calvert, counsel for the HA, said the Treasury has an innovative approach, "at least a third of the funding is to come from heritage sources in recognition that the tunnel component is specifically to provide environmental benefits for Stonehenge".
Overview of the proposed tunnel scheme at Stonehenge and the longer tunnel advocated by the National Trust