Belfast Telegraph

Boris Johnson's bridge from Scotland to Ireland is feasible, say experts

A sketch by architect Alan Dunlop of the bridge proposed by Johnson
A sketch by architect Alan Dunlop of the bridge proposed by Johnson

By Brett campbell

Boris Johnson’s plan to build a bridge linking Northern Ireland and Scotland has been endorsed in one of the most authoritative scientific publications in the world.

Independent engineers quoted by National Geographic concluded that the towering structure would cost “a lot more than the £15bn” suggested by the Prime Minister.

They also found that the engineering involved would be “more than a little” complicated.

But ultimately, they all agreed, it is technically possible.

Scottish architect Alan Dunlop suggested two viable routes: a 12-mile crossing that spans the shortest gap between Torr Head and the Mull of Kintyre, and a 26-mile crossing from Portpatrick to Larne.

According to Mr Dunlop, the latter route is more practical because of less remote ports and better road infrastructure at each side.

He notes that the depth of the seabed — which is up to 160 metres at its deepest section — poses a greater challenge than building to the required length.

Alan Dunlop
Alan Dunlop

The expert has proposed a cable-stayed or suspension bridge for the shallower sections and a floating pontoon-style bridge “tied to the seabed with cables” for the deeper sections.

“This would be a challenging proposition,” he admitted.

“But we have the technology and the talent in Ireland and Scotland to create something as potentially brilliant as this.”

Mr Dunlop dismissed critics who have warned that tempestuous weather in the Irish Sea would mean the project remains nothing more than a pipe-dream — and cites the 34-mile Hong Kong-Zhuhai-Macau Bridge as an example of how challenges can be overcome.

“That was designed and built to withstand typhoons. We have the engineering expertise to do that,” he said.

The series of cable-stayed bridges, which features an undersea tunnel and four artificial islands, opened in China last year.

Structural engineer Ian Firth
Structural engineer Ian Firth

Mr Dunlop said his route would be further north of Beaufort’s Dyke, which is filled with over a million tons of dumped munitions and radioactive material.

The architect estimates the cost to come in at around £15 to £20bn, which could be clawed back through the introduction of a toll system similar to the 4.9-mile Oresund Bridge which links Sweden to Denmark.

British structural engineer Ian Firth agrees the longer route is the best option, but stressed the seabed depth is a challenge.

However, he outlined three possible designs which he believes are feasible, including the eyebrow-raising option of a submerged tube — effectively an under-water tunnel — attached to floating pontoons at the surface or tethered by cables to the seabed below.

“I’m convinced it’s doable,” he said. “It’s not been done before but we’ve designed similar bridges.”

Mr Firth said the cons to either option included the risk of collision presented to ships and submarines, and the potential chaos resulting from a fire or accident deep inside the tunnel.

The expert refused to speculate on the cost as he acknowledged that while all three designs have precedents, none are on the same colossal scale.

Naeem Hussain, a global bridge design leader for international engineering group Arup, agreed that a Portpatrick-Larne bridge is “entirely practical and doable” — but would require upgraded roads on the Scottish side.

The expert estimates the cost to be between £20-£30bn, which means the only question remaining is whether supporters of the proposal, such as the DUP, can stomach the cost.

Belfast Telegraph


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