Larne-Stranraer fixed link: technically possible, but stupidly expensive

To build a bridge between Stranraer and Larne, together with all associated links to make it work, would cost £335bn. A tunnel would cost £209bn.

The analysis is based on a bridge similar to Cowi’s Yemen-Djibouti Bridge and a tunnel similar to the Channel Tunnel.

The details are contained in an annex to the Sir Peter Hendy’s Union Connectivity Review, published today*.

In October 2020, Network Rail chairman Sir Peter Hendy was asked by the prime minister to lead a detailed review of how the quality and availability of transport infrastructure across the United Kingdom can support economic growth and improve quality of life.

As part of the review, he was also asked to assess the technical engineering feasibility of constructing a fixed transport link between Great Britain and Northern Ireland. Undertaken as a separate workstream, in March 2021, professors Douglas Oakervee and Gordon Masterton were appointed to lead the study. At the same time, a partnership of Jacobs and COWI was appointed by the Department for Transport to provide independent engineering expertise to the technical advisors.

This report** concludes that it could be done, but it would be crazy to do so.  

Or more formally: “Twenty-first century civil engineering technology would make it possible to construct either a bridge or a tunnel between Great Britain and Northern Ireland. A bridge crossing, however, would be the longest span bridge built to date. A tunnel would be the longest undersea tunnel ever built given the limited gradients on which trains can operate, the route it would need to take and the depths it would need to reach. In addition, based on today's technology and safety considerations, a tunnel crossing could only be constructed for railway use.

“The indicative cost estimate for the full route, including optimism bias (at P95), is £335bn for a bridge crossing and £209bn for a tunnel crossing. The bridge or tunnel, and the associated very significant works on either side for a railway and possibly for roads would take a very long time. Planning, design, parliamentary and legal processes, and construction would take nearly 30 years before the crossing could become operational, even given a smooth passage of funding and authority to proceed.

“Whilst the economic and social effects would be transformational, the costs would be impossible to justify.”

Sir Peter Hendy concludes: “Future transport technological advances, particularly autonomous vehicles, could allow for different tunnel and bridge designs, which could enable the construction of a fixed transport link and approaches at a lower cost. For now, though, the benefits could not possibly outweigh the costs to the public purse. It is therefore my recommendation to government that further work on the fixed link should not progress beyond this feasibility study.”

So was the whole exercise a waste of time and money? Sir Peter Hendy doesn’t thinks so.

“Despite my recommendation, I am clear that this was an excellent question to ask,” he says. “For many decades, politicians and engineers have debated this proposal, but have done so without the evidence to show whether it was possible and, if so, what it would take to do it. This is the first comprehensive, conclusive study on the subject since the idea was first mooted over 150 years ago.”

* Union Connectivity Review: Final Report can be downloaded as a pdf here

**A Fixed Link between Great Britain and Northern Ireland: Technical Feasibility can be downloaded as a pdf here

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