Major changes in the design of the Dublin Port Tunnel will add at least £30 million to its cost and postpone its completion until late 2003.
Work on the 5.6km route was supposed to start last year and finish in 2001. But the controversial project, which has provoked widespread opposition from residents of the affected areas, is not expected to start until spring 2000.
The biggest change involves a 1km extension of the tunnel from Whitehall to Coolock Lane, in line with the wishes of Dublin City Council when it decided last September to incorporate the scheme in the city plan.
In an effort to reassure residents of Marino, who have been waging a vigorous campaign against the tunnel, the engineers have also decided to build it at a greater depth beneath houses in the area to minimise noise disturbance during construction.
Details of these design changes were revealed yesterday with the publication by Dublin Corporation of a new environmental impact study and a motorway order documenting the extent of compulsory land acquisition.
This includes the sub-strata through which the tunnel would be constructed. In each case, householders with property on the line will be entitled to compensation.
Mr Gerry Duggan, the corporation's project engineer, would not be drawn on the amount of money but every householder - some 300 altogether - is likely to get at least a few thousand pounds. To overcome doubts about whether public agencies had the power to acquire sub-strata for a tunnelled road scheme, the Minister for the Environment, Mr Dempsey, introduced a Bill last December to make this explicit. It finally became law on July 1st.
Overall, property acquisition could cost up to £7 million - mainly because of inflationary pressure on land values, particularly in the vicinity of Dublin Port. But Mr Duggan said this was quite a small sum for a project now estimated at £179 million.
The latest five-volume study comes exactly two years after the original EIS went on public exhibition in July 1996. Accompanied by scale models, aerial photographs, interactive "touch screens" and a video, it is being exhibited at the Civic Offices until August 17th.
The twin bored tunnels have been separated going under Marino to run underneath roads or back gardens, rather than houses, to the greatest possible extent. In general, they will be 10 metres deeper than was envisaged under the earlier scheme.
A cutaway model of houses in Croydon Avenue, Marino, shows the tunnel running underneath at a depth of up to 23.5m. At this depth it will run through limestone bedrock rather than less stable ground.
Affected householders would be able to choose from a panel of independent surveyors for the purpose of surveying their homes in advance, during and after construction. "If there is any damage to property, it will be remedied," Mr Duggan declared. The engineers intend to relocate the construction compound from a surface car park site beside Whitehall church to open land south of Collins Avenue in deference to the wishes of local residents. This land, part of Hyde Park convent, must be also be acquired.
Referring to the extended tunnel from Whitehall to just south of Coolock Lane, he said this would be done as "cut and cover", involving the excavation of a kilometre-long trench 17m wide and 20m deep - right in the middle of the M1 motorway. This work, to be done in two parallel phases, would reduce the motorway to a single lane in each direction for about 15 months. The route would also be closed completely for two weekends while the Shantalla Road bridge is demolished and replaced. From Whitehall to Fairview, the tunnel would be bored for a distance of 2.4km. Through Fairview Park, it would be "cut and cover", requiring an excavation some 45m wide and 25m deep as well as the felling of around 30 mature trees.
The entire project is being done as a joint venture by Dublin Corporation, Ove Arup and Partners and Geoconsult, from Austria. It will not go to tender as a "design and build" contract until next summer after the legal formalities have been completed.
According to the current timetable, objections to the motorway scheme must be lodged by August 17th. The Minister for the Environment would then direct that a public inquiry be held, probably next January, before deciding whether to approve the scheme.
Asked why the port tunnel had managed to hold on to its EU funding when Luas lost its allocation due to similar delays, Mr Duggan said 85 per cent of the finance was coming from the Cohesion Fund, which was more "project specific" than the Structural Funds. Th EU has also co-financed the £6 million spent so far on the planning and design of the tunnel. Dublin Corporation also believes it's a "very good scheme", significantly different to the earlier version because of the concessions made to local interest groups.
It maintains that with Dublin Port experiencing unprecedented growth, with last year's freight throughput up 11 per cent to a record 16.8 million tonnes, the need for a direct link with the M50 and national road network has become more urgent than ever.
However, the scheme is certain to be opposed by a coalition of residents' associations, the Marino Development Action Group, as well as by Santry residents living near the relocated northern portals, where air pollution is likely to increase, as the EIS concedes.
