THERE’S no doubting the power, symbolic or otherwise, of a mighty bridge. Earlier this week, we saw the initial sketches of a proposal to link up Scotland and Northern Ireland. The shorter option is between the Mull of Kintyre and Torr Head; the longer, between Portpatrick and Larne.

The pencilled impression of the “Celtic Bridge” suggests a design that’s like a copy-and-paste of the Queensferry Crossing over the Forth. Like that bridge, many “cable stays” peak and trough their way across the Irish Sea. But the artist puts it all in scale by sketching in a family, plowtering about on a harbour beach, gazing out at the massive structure.

REVEALED: First images of potential Scotland-N Ireland bridge as architect promotes project

That looks right. We feel connected to our bridges, because our bridges connect us. Although you can find them far back in the human record, they are properly a sign of modernity. As acts of engineering, they made possible the movement that the industrial age required, in the transportation of materials, goods and workers.

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So even when it’s tied to tourism, supermarket supply-chains and personal convenience, as much as it is to heavy industry, the announcement (and completion) of a major new bridge sends a familiar old tingle of progress down our spines.

We’re not where we were, of course. The Queensferry had only a mild input from Scottish manufacture, design and engineering. It was otherwise sourced from the US, Denmark, Holland, Sweden, Germany, China and Switzerland (where those cable stays come from).

One would imagine that the Celtic Bridge arising out of no less global a stew. (Though I suppose, if we wanted to improve matters, it could drive demand for a more interventionist style of Scottish industrial policy.)

We’re also not where we were, as far as the assumed worth of a mega-bridge is concerned. I’m a pal of the Scottish Greens, but they were broadcasting from Planet Virtue when leading figures like Andy Wightman described the Queensferry as a “vanity project”.

More pertinent was the charge that it was utterly car-centric, without even a pedestrian route (though one of the remaining Forth bridges welcomes cyclists).

It’s a Green’s job to point out how toxic, inefficient and atomised individual car usage is – and to oppose infrastructure which invites more of the same. They accept pelters for the sake of the planet.

Due to unimprovable klutziness, I will never get it together to be a driver, and so I’m naturally in their constituency. But when strapped into a tour van recently, it was impossible to suppress the joy of approaching, going over and leaving behind a bridge like the Queensferry.

It’s like the whole society has decided to defy gravity and the natural elements; to set our own human and monumental challenge to the surrounding hills.

I get a similar surge from gazing at oilrigs, or imagining the red glare rising from the forthcoming Sutherland spaceport.

A gentle procession of wind turbines might be enough of a technological sublime for Scottish Greens. But I’d suggest if they want to sweep the hearts and minds of the nation, they might want to start developing some positive lines on a possible Celtic Bridge.

Certainly, there’s something beautifully human-scale about the idea of walking (or cycling) over the sea to the island of Ireland – indeed, tangibly spiritual and religious (could another name for it be the Columba Bridge?) So yes, it shouldn’t be just about cars and trains.

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The proposer of the project, Professor Alan Dunlop, is already pushing all the cultural and political hot buttons on his dashboard. This would be an investment in the “true North” of these islands, as he puts it – much more substantial than any city-deal baubles dangled before the major cities either side of the Tweed.

And in the general unsettlement of boundaries going on at the moment, a Celtic Bridge could play a somewhat unpredictable part. (Did the pricey and bourgeois EuroTunnel ramp up popular Euroscepticism, as much as it physically defies it?) The Democratic Unionist Party have fully endorsed Prof Gordon’s project, no doubt as a robust reinforcement of the ties of Union.

They might be ultimately disappointed. Bridges seem to be able to handle both independence and interdependence. The gigantic Øresund Bridge, linking Copenhagen in Denmark and Malmo in Sweden, has undoubtedly created a thriving cross-border economic zone. Here are two EU-integrated nations overlapping Nordically, at their

own pace.

In a recent visit to Copenhagen, the structure looked massively significant to me – like two curved arms, meeting across the water. Yet the Københavnere were still jabbering away in Danish, as far as I could hear.

As the Brexit mess slowly coagulates, a Celtic Bridge does feel like the kind of autonomous act that might keep us all sane, as the post-imperial trauma down below disruptively works itself out.

Bridges may accelerate the present – but they also unearth the past. One of the obstacles to the Celtic Bridge literally fizzes and burbles with the evils of history. Beaufort’s Dyke is in the pathway of the bridges – an underwater trench 50 kilometres long, five kilometres wide and about 250 metres deep.

Between 1945 and 1976, the MoD dumped about 1 million tons of munitions into and around the trench. These were explosives of all kinds, but also chemical weapons like mustard gas and sarin. Gas pipeline developers started digging at these areas in the mid-90s, which turfed phosphorous bombs onto local beaches to burn paddling kids.

The good Professor Dunlop tells us that recent advances in “floating bridges” could manage this stretch of the Celtic Bridge. Maybe so. But it’s a fascinating press on the pause-button – and richly ironic. The worst outcome of our human ingenuity arises, from the depths, to challenge one of our best.

Here is an underworld which the late Iain Banks would have relished. His 80s novel, and masterpiece, The Bridge – constructed consciously in the style of Alasdair Gray’s Lanark – explores these structures’ metaphoric power to the full. (It’s perhaps no surprise: Banks grew up in a Queensferry home, with the giant rusting red bridge filling his childhood bedroom window. It’s also the place where he later solidly settled as an adult).

Banks’s bridge is not only the place where an individual’s life is literally upturned, where a moment’s inattention throws a driver into a post-crash coma. While in that condition, he imagines a world with an even vaster bridge, stretching to each horizon. Underneath and upon it, a vibrant civilisation teems. Beyond it lies barbarism and disease.

It’s the artist’s role to scan the unconscious for our deeper anxieties about the direction of our lives and societies. So I wouldn’t wait for Banks’s dark classic to be easily deployed in the bridge-promotion brochures any time soon.

Yet Iain does show what we really invest in our bridges – and it’s much more than our tax spend, or the procurement of local contractors.

In a world where the big shaping forces seem inaccessible, and our small actions seem ineffectual, a bridge is quite something for a national community to agree on. It’s a sign that the elements can be visibly tamed, and history tangibly directed, by the march of stanchions and the thrum of cables. No wonder that Scotland, permanently seeking the case for optimism, is thinking about building another big beauty.