One of the most ambitious tunnel boring projects over the past two decades is the multiple tunnels that are being created as part of the High Speed 2 rail project, using some of the most advanced TBM designs and conveyor rollers.
However, at one point it seemed like an even more ambitious tunnel, hypothesised for over two centuries was close to receiving the green light until a feasibility study closed the door on this proposal.
Ever since Northern Ireland has been part of the United Kingdom, there have been plans to create some form of link that could connect the British Isles across the Irish Sea, with the first being a somewhat sarcastic proposal by William Pitt The Younger, then an Architect but soon the Prime Minister.
In the early era TBMs that would have made an Irish Sea tunnel remotely possible, several proposals were suggested to build between Scotland and Northern Ireland, with the one most progressed being between Belfast and the town of Stranraer.
The problem was financial in nature, and whilst there was the potential upside of faster transatlantic travel via Irish ports, ultimately the plans did not go ahead.
A similar proposal was never made in 1915, where a tunnel was proposed as a way to stop the potential of a supply blockade by dangerous German U-Boats, but starting a slow, ambitious and expensive tunnel project during the middle of the First World War was unlikely to happen.
Several debates took place surrounding the feasibility of the tunnel but the problem was outlined by the Irish Minister for Tourism and Transport John Wilson in 1988; a feasibility study suggested it would cost twice as much as the Channel Tunnel did and generate a fifth of the income, with travel taking place by air rather than by sea.
The concept was revived in the early 2010s, with a comprehensive study taking place to see what the cost would have been. Ultimately, the £209bn cost was seen as too expensive to justify and would have made it one of the most expensive infrastructure projects in history.
