THE estimated cost of Dublin Port Tunnel and the M1 motorway has jumped by €100m in just one month, according to the National Roads Authority.

The 38km of M1 motorway from Dublin airport to beyond Drogheda, due to open this summer, will have a final price tag of more than €460m — up from a previous estimate of €409m.

The price increase for the 6km port tunnel is even more striking. The estimate has gone from €625m in March to more than €670m in new figures that will be reported to the department of transport this week.

That is more than three times the 1996 estimate of €213m for a single carriageway tunnel with lower specifications and capacity. The cost of the final link in the M50 — the south-eastern motorway — is currently being driven up by as much as €200,000 a week. That’s largely because of a court injunction in a case taken by conservationists to save the site of Carrickmines Castle, which is on the proposed route.

Dun Laoghaire-Rathdown county council faces a compensation claim from Ascon, the road builders, because of the delay in waiting for a High Court hearing to rule on whether the Carrickmines site is a national monument.

The most recent cost estimate for the south eastern motorway is €595m, but this does not include the mounting compensation bill. The disturbing snapshot of motorway inflation will be outlined in detail in a fortnight when Seamus Brennan, the transport minister, unveils the first of his promised monthly reports on major infrastructure projects.

The costings will lend weight to the minister’s plans to draft critical infrastructure legislation to fast-track major civil engineering projects through the expensive legal processes of planning and compulsory purchase.

The NRA, under fire over the issue of inflation in road construction, has not yet released the new figures.

Commenting on previous estimates, Michael Egan, head of corporate affairs at the NRA, said that land costs had risen from 8% of overall motorway costs to around 12% in just 18 months since a state-brokered deal with the Irish Farmers Association. This is mirrored in urban areas.

Site purchase accounted for more of the €595m bill for the south eastern motorway than actual construction costs.

Senior sources in SIAC Construction, one of Ireland’s largest civil engineering firms, noted that legal costs associated with major projects were running significantly ahead of continental European levels.

SIAC’s joint venture partners on the €300m Kilcock-Kinnegad by-pass, Ferrovial, said the legal costs for the single Irish motorway were equal to the legal bills for some €3.5 billion of projects in Spain.

Brennan’s senior officials are expected to seek the advice of Rory Brady, the attorney general, before trying to shift the balance of rights in the area of property ownership. Any attempt to put “the public interest” ahead of private constitutional rights to hold property will doubtless face a challenge under the constitution.

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