MORE than €4m has been spent carrying out a feasibility study on a motorway scheme that will not be built for at least a decade.

The massive study was carried out on a proposal for a multibillion eastern bypass to carry traffic past Dublin city centre by way of a huge bridge and tunnel scheme across Dublin bay.

The National Roads Authority (NRA) said they could not disclose an exact figure for the cost of the feasibility study as it had been carried out under an open tender. However, a spokesman did confirm the final cost of the feasibility scheme was between €3m and €5m. He said: "It is a highly detailed study that encompasses all of the different options and the level of expertise is of a very high quality.

"The study was commissioned some time ago but it is still relevant despite the changed economic conditions. Because of the level of detail contained in the report, it is still relevant even if a significant period of time elapses before any scheme goes ahead. The engineering involved of what kind of bridge or tunnel will still stand and the environmental studies and traffic modelling will not change much."

A source in the NRA admitted the study had cost in excess of €4m but said the project may benefit from reduced land values. The source said: "What has changed since the report was carried out is that property costs and labour costs have dropped significantly, which would bring the cost of the bypass down."

The cheapest option in the report proposes a massive bridge across both the River Liffey and another one across Sandymount Strand at an estimated cost of €3.95bn.

The second option, which would cost €4.2bn, includes a bridge across Dublin Port along with a tunnel scheme under Sandymount and Booterstown. The third and most expensive option is a tunnel from Dublin Port to the south of the city at a cost of around €4.35bn.