A new report claims it would cost more than £40 billion to build a bridge between Dumfries and Galloway and Northern Ireland.
The British Ports Association, which commissioned the study, have branded the idea as “a redundant and irresponsible use of public money”.
The idea of a transport link between Scotland and Northern Ireland was included in the Union Connectivity Review earlier this year.
In his findings, Network Rail chairman Sir Peter Hendy said he had asked experts to look at the feasibility, cost and timescale of building either a bridge or a tunnel, the latter being Dumfries and Galloway MP and Scottish Secretary Alister Jack’s preferred option.
Prime Minister Boris Johnston has previously described a bridge linking Portpatrick with Larne as “a very interesting idea”.
Critics dismissed the idea as “a vanity project”.
And the BPA report “I Have a Bridge to Sell You: Making The Case for Port Connectivity” casts doubt on the proposal.
It claims that while a leading engineering firm has provided an estimated cost in the region of £20 billion, “such projects have a high likelihood of cost overruns of 80 per cent”.
The report also says there would be a need to upgrade road and rail links if the route of Portpatrick to Larne was chosen.
As a result, they believe the “overall costs could exceed £40 billion, with a negligible return on investment expected”.
The report adds: “This sum is before continued operations and maintenance are considered.”
BPA’s policy manager and economic analyst Phoebe Warneford-Thomson, who wrote the report, said: “This report makes clear that government’s suggestion of a fixed link between Great Britain and Northern represents a redundant and irresponsible use of public money.
“It would be much better spent on other infrastructure priorities.
“The BPA has prepared a comprehensive port connectivity programme which sets out a productive alternative plan for investment.
“Our plans are a fraction of the cost of the fixed-link with an anticipated 400 per cent return on investment derived through cost savings for businesses with a positive impact on emissions and the net-zero agenda.
One idea included in the report is dual carriageway extensions on the A75 and A77 to improve access to the ports at Cairnryan.
