Sanjoy Sen is a chemical engineer in North Sea oil. He contested Aberdeen North at the 2015 general election and Alyn & Deeside in the 2019 general election.

Conservative Home is rarely wrong: as per the italicised introduction you see above, I am indeed a chemical engineer. But to be precise (something us engineers often insist on), I’ve spent the last few years working in the field of development engineering, both in industry and in government. That includes the objective evaluation of multiple concepts before recommending which, if any, to proceed with. And, in the energy sector, that can influence multi-million pound decisions.

So, I’d be chucking away years of training and experience were I to pen an over-enthusiastic, ‘Build it!’ piece on the Scotland-Northern Ireland bridge concept. We haven’t seen even the most preliminary techno-economic analysis as yet. But, as an engineer, I’m glad we’re at least starting to give big infrastructure ideas some long-overdue consideration.

Let’s be clear, though: the political implications of the bridge aren’t exactly insignificant, either. Those who back an independent Scotland aren’t just sceptical for engineering reasons. And then there’s the potential impact on Anglo-Irish relations following general elections either side of the water. On one level this is an infrastructure investment, on another it’s an investment in the union itself.

First things first. It’s absolutely right that folks should ask searching questions: is it technically feasible, can we afford the investment, what economic benefit might it deliver, are there better uses for the same money. But one thing we need to tackle is the seemingly all-pervasive ‘can’t do’ attitude.

Switch over to the Discovery Channel and you’ll find no end of documentaries on mind-blowing Asian mega-structures: bridges, tunnels, sky-scrapers etc. Some are strategically vital whilst others resemble expensive vanity projects. But, either way, if someone told you that the Chinese were thinking of building a challenging sea bridge between two provinces, you’d back them to deliver on it. Sadly, big ideas in the UK often tend to attract more derision than enthusiasm. That’s hardly surprising given our recent track record on infrastructure but, looking ahead, we do need to develop a mindset of believing that we can deliver big projects when we choose to.

What are the technical considerations?

Those in engineering will tell you that Britain and Ireland are already linked by some pretty significant infrastructure: subsea gas pipelines plus cables carrying high-voltage power and communications. But carrying people and goods on board vehicles (and maybe even trains) is clearly in another league.

Much greater distances and water depths have already been spanned globally but not strictly in the combination required (20+ miles long, 150+ metres deep) between Larne and Portpatrick. And whilst major Baltic Sea projects (home to some 150,000 mines) have been delivered following extensive seabed clearance, including the NordStream Russia-Germany pipeline, the 1 million tonne munitions dump at Beaufort’s Dyke is clearly an issue.

And whilst, for brevity, I keep referring to a bridge, who’s to say it wouldn’t be a submerged tunnel instead? Or even some bridge-tunnel combination as per the Sweden-Denmark Øresund crossing? Perhaps the most intriguing suggestion I’ve spotted so far is a floating pontoon arrangement inspired by deepwater oil & gas technology: we’d have the know-how in Aberdeen to look into that.

So whilst the project would undoubtedly be technically challenging, the key questions are not necessarily engineering-related but economic. Even in an otherwise sceptical piece, as one academic put it “from an engineering perspective, it’s not by any means impossible – it’s definitely possible to do. There’s just a significant amount of challenges that would need to be overcome.” 

What of the economic considerations?

On a smaller scale, Alyn & Deeside (where I recently came within 213 votes of winning) is home to the £55 million Flintshire Bridge, an elegant cable-stayed construction over the Dee. Grossly under-used since opening in 1998, this ‘bridge to nowhere’ isn’t in itself the problem: it’s the limited road network on either side that prevents it from realising its intended purpose as a valuable cross-border link between north Wales and England.

For the ‘Boris Bridge’ concept to deliver real value, it’ll need to be framed in terms of an area infrastructure project, not solely the bridge. Having recently undertaken the car journey to the Cairnryan ferry port along the A77 (from Glasgow) and back along the A75 (towards Carlisle), I can vouch for how urgently both require dualing. Once established, though, fast, large-capacity connections between Belfast and major British cities could prove a game-changer – on both sides of the water.

What of the political dimension?

Whilst engineers and economists will be poring over their spreadsheets for answers, the SNP will presumably be in no doubt already that it’s a terrible idea. For now, Sturgeon and Blackford can cheerily dismiss the idea and demand the funds for alternative uses. But if it begins to look real, challenges await.

Dumfries & Galloway remains a somewhat over-looked corner of south-west Scotland, its cause not helped at Holyrood by voting two-thirds against independence and continuing to return Conservative MPs and MSPs. Infrastructure is limited and average earnings are low. And despite wonderful scenery and great history, most tourists tend to plough straight on towards the central belt and on to the Highlands. There’s potential in this ‘left behind’ area.

The fact that some pretty unlikely places in England and Wales recently went blue shouldn’t be lost on the Nationalists. Construction opportunities (hopefully with UK suppliers to the fore) and a subsequent regional economic boost could well strengthen and spread pro-union vibes. And if pro-independence support dips even slightly as a consequence, the Nationalists might find themselves tipped from stable equilibrium to the point of collapse faster than you can say Tacoma Narrows Bridge.

At this stage, without even preliminary assessment, no-one can call the viability of the concept. (And, in fairness, even when the numbers are crunched, estimating investment costs and economic returns on large, bespoke projects carries much uncertainty.) But who’s to say it won’t deliver more pound-for-pound value than other mega-projects, deliver more ‘levelling up’ across the UK and perhaps even help preserve the union itself? For now, it has to be a good thing that we’re at least thinking about the Boris Bridge.