Scottish proposals offer multiple tunnel opportunities

30 September 2020

Transport Scotland has requested comments on 11 project corridor options for the Access to Argyll and Bute (A83) project, many of which offer numerous possibilities for submarine tunnels. The UK tunnelling sector is in a prime position to promote tunnel solutions to some of the requirements for fixed links.

All 11 options involve 2km-wide study areas of varying lengths which must negotiate a sinuous array of loch and high ground areas, traversing in the process much of the region’s famed natural beauty. Some of the options are relatively straightforward, involving the construction of new carriageway and road upgrade works. But some could see the region become a focus for considerable tunnelling activity as tunnels can provide a solution that is more suited to the terrain and the activities that go on within it.

For example, Option 6 foresees a 3.9km fixed link across the Firth of Clyde and is said to present considerable challenges as it is used by large ships and MOD submarines. Challenges for a bridge solution maybe, but not for a tunnel, whether bored or an immersed tube.

Option 7 also envisages a fixed link across the Firth of Clyde, while Option 8 contains the possibility of two tunnels of 2.65km and 2.53km to form a fixed link between the mainland and the Isle of Bute via Little Cumbrae Island (‘Wee Cumbrae’); a further undersea tunnel could span the 0.5km between the Isle of Bute and Cowal – currently served by a ferry crossing.

The Project Corridor Options (Access to Argyll and Bute (A83)) have been identified by Transport Scotland’s Strategic Transport Projects Review team and the feedback it receives to the eleven options will form the basis for the first stage of data collection.

The closing date for the submission of comments is Friday 30 October 2020 after which Transport Scotland will look to make recommendations in Spring 2021 for a preferred route corridor with alignment options.

For full details of the route options and to comment go to