The costs associated with constructing the Shannon tunnel scheme, the largest road project in the west of Ireland, are now put at €660 million, the National Roads Authority (NRA) confirmed yesterday.
The revised cost is an 86 per cent increase on a 2004 estimate by then minister for transport Séamus Brennan.
Mr Brennan said then that the second phase of the Limerick Southern Ring Road - including the 675m (2,215ft) tunnel under the river Shannon - would cost €355 million.
However, an NRA spokesman said yesterday: "The 2004 figure was based on 2001/02 land values, was not inclusive of the cost of inflation and was an estimate."
He added: "It should be noted that the €660 million cost refers to design, construction, maintenance, operation and re-investment tasks."
The scheme is a public-private partnership with a consortium called Direct Route securing the contract last year. The NRA spokesman said that the cost to the State of the scheme is €349 million.
The spokesman said that the cost of land, preliminary studies to identify the route, advance ground investigation, initial archaeological testing and supervision of its construction would amount to €150 million.
Upon completion, in 2010, the project is expected to end the daily gridlock in Limerick city and remove 40,000 vehicles from the city's arteries. The project will link all the main routes - Dublin, Cork, Kerry, Ennis/Shannon - converging on Limerick.
Along with the tunnel, the scheme involves 10km of road, 11 bridges and a 750m causeway across Bunlicky lake. The NRA spokesman described the scheme "as the largest infrastructural scheme in the west of Ireland that no one knows about".
Much of the work is taking place away from public view on lands north of the river Shannon where the tunnel is being constructed in a dry basin, which the general manager of Direct Route, Tom King, described yesterday as a "mini Grand Canyon".
A team of 400 workers has been working for a year on the tunnel, which is to be constructed in five separate 100m elements. The first section is complete.
Next August, the contractor will flood the casting basin before winching the completed tunnel sections into a dredged section of the Shannon.
The "immersed tube tunnel construction approach" was used to build Cork's Jack Lynch tunnel.
The route is set to be the first tolled road in the west of Ireland and the toll scheme anticipates that the route operator will generate €456 million from tolls over 30 years.
Mr King said that the agreement with the NRA ensures that there is a capping of profits, while the NRA has guaranteed a minimum return to the operator.
The NRA spokesman said that the contractor "resembles a giant walking on his tip-toes" in dealing the various environmental challenges on the scheme.
As part of the works, Direct Route has had to individually relocate 2,500 protected plants from the construction site and place a large proportion of them in water tanks, recreating the tidal conditions on the Shannon.
