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NATM rejected as Dublin tunnel costs double

DUBLIN'S PORT tunnel construction contract has been awarded at almost twice the budgeted price and rules out the use of the controversial New Austrian Tunnelling Method.

The Irishenco/Mowlem/Nishimatsu consortium's £265M bid beat four rivals with a proposal to use two tunnel boring machines to drive the twin 4.5km motorway tunnels. Design work is by consultants Charles Haswell and Carl Bro.

But NATM, originally mooted by Arup and Heathrow collapse consultant Geoconsult in detailed pre-tender designs started in 1994 (NCE 19 January 1995) was offered as a solution by only one of the five tenderers.

The scheme was only approved by the Irish Government in 1994 after cost savings were gained by incorporating a 2.4km section of NATM lining and realigning the tunnel to shorten it. In 1994 the project was only expected to cost £78M.

However, the new route took the tunnel under 300 houses in the suburb of Marino, provoking fury among residents. They objected to the use of NATM under houses and to the retention of Austrian consultant Geoconsult after its involvement in the 1994 Heathrow Express collapse.

The latest price hike is likely to cause serious government concern after warnings in September that escalating tender prices could threaten the country's £15bn infrastructure programme.

But according to client Dublin Corporation, the winning bid was the lowest price. Deputy project engineer Hugh Creegan said: 'This is a reasonable price, and the funding has already been allocated by the National Roads Authority.'

He added that the decision on which tunnelling method to use was left to the bidders and that NATM had never been a stipulation, with all methods being considered.

Creegan said that a combination of construction cost inflation, local contractors working to full capacity and fulfilment of local residents' concerns had all added to the cost.

Secretary of the Marino Development Action Group Fintan Cassidy claimed victory. He said: 'We are extremely pleased. The dropping of NATM is a huge victory for us'.

However, Geoconsult, which still refuses to pay a £500,000 court fine imposed for its role on the Heathrow tunnel collapse, is understood to be bidding for the site supervision contract as subcontractor for a Lahmeyer/ Nicholas O'Dwyer joint venture.

Arup will part ways with the Austrian consultant when the preliminary design contract ends shortly, to join a consortium with Halcrow and Sodeteg.

Winning the Republic of Ireland's largest ever civil engineering contract is a major coup for Mowlem which bought local firm Irishenco from receivership in 1998. It is also part of one of the two consortia shortlisted for the Dublin Light Rail contract due for award later this year.

Success would propel it to the top of the Irish contracting orders league.

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