• An architect estimates a bridge between Ulster and Scotland would cost 15 billion pounds
  • Boris Johnson has long advocated for such a bridge
  • Critics contend such a bridge is too costly and unnecessary

A proposed bridge across the North Channel of the  Irish Sea linking Northern Ireland and Scotland has received the support of Leo Varadkar, the prime minister of the Republic of Ireland. British Prime Minister Boris Johnson and the Democratic Unionist Party of Northern Ireland have also spoken favorably of the idea.

However, after Varadkar suggested to Johnson that the U.K. should pay for the bridge, Johnson said it should be the European Union’s responsibility.

"So that's definitely not going to happen, because neither Northern Ireland or Scotland are going to be in the EU,” Varadkar said. “But it was kind of half-serious, half-joking in a way. But all messing aside, I do think at the very least a high-level engineering assessment should be done as to whether [the bridge] is a viable proposal."

Varadkar added: "I think we need to at least check out if this is viable in engineering terms and how much money it would cost to do."

Professor Alan Dunlop, Fellow of the Royal Incorporation of Architects in Scotland, estimated that the "Celtic bridge" would cost about £15 billion ($19.9 billion), which is far less than the £120 billion ($159 billion) estimated cost for the proposed English Channel bridge between England and France.

Dunlop has proposed two possible routes for the bridge. One route would be from Larne, Northern Ireland, to Portpatrick, Scotland, and the other would be between the Mull of Kintyre in Scotland and Torr Head, Northern Ireland.

"[Scots and Irish] share a lot of history together, similar ideals,” Dunlop said. "The business potential is exceptional, the chance of actually really making an investment in what would be the true north."

Dunlop believes such a bridge would greatly benefit the economies of both Scotland and Northern Ireland post-Brexit.

"It would be something we could debate around Brexit,” he said. "Engineering-wise and architecturally this could be an investment in the infrastructure of Scotland and Ireland."

Dunlop added that a bridge to link Scotland to Ireland is “a project fit for the 21st century.”

“There is also interest internationally,” he said. “I've spoken about it with colleagues in the U.S. and on visits to Australia and China this year. We have the engineering and architectural talent here in Scotland to create such a structure.”

Dunlop has urged Scottish First Minister Nicola Sturgeon to settle her differences with Johnson in order to cooperate on the proposed bridge.

The Democratic Unionist Party of Northern Ireland even included the bridge in its recent election manifesto.

“If the feasibility study on a bridge between Northern Ireland and Scotland concludes positively, this should also be pursued with the national government and devolved institutions working together to take it forward,” the manifesto read.

Scottish Secretary of State Alister Jack said: “I love the idea of a bridge joining us with Northern Ireland. We will have a feasibility study into it. That is the route forward, and we will see where that takes us.”

Samuel Wilson, a Democratic Unionist Party politician from Northern Ireland, also supports building the bridge, claiming it would create a "physical and economic link” between the two regions.

"I think one of the big themes of this parliament will be how you protect the union of the United Kingdom and I think Boris cannot ignore the threat to the union that comes not just from Sinn Féin in Northern Ireland but also from Scotland," Wilson said. "He has got to take more seriously the role he has as prime minister in selling the advantages of the union, taking steps to strengthen the union and ensure that there is growth not just in the north of England but in Scotland, Northern Ireland and Wales."

Gordon Lyons, another Democratic Unionist Party member, said such a bridge "would be a catalyst for further economic growth in both Northern Ireland and Scotland, whilst also recognizing the strong economic, cultural and social links between the two regions.”

However, some think a bridge is a bad idea.

Sinn Fein, an Irish republican political party that operates in both Northern Ireland and the Republic of Ireland, dismissed the bridge idea as "fantasy politics.”

"Boris Johnson has a penchant for talking about and engaging in fantasy politics rather than addressing the reality of the chaos of the Tory Party, the British parliamentary system, and the mess that is Brexit," said Sinn Fein member in Northern Ireland Mickey Brady.

Others on both sides of the Irish Sea also rejected the bridge as too expensive and unnecessary.

"Big infrastructure projects can be transformative," said Scottish economist George Kervan. "But the trouble with this one is just the costs will kill it. And £15 billion -- I can think of a lot of other things to do with that."

Ulster Unionist Party leader Steve Aiken said such resources would be better spent on upgrading Northern Ireland's existing infrastructure.

"Could we rather have the money for a 30-year strategic infrastructure [program] to rebuild [Northern Ireland] for the 21st century?" Aiken tweeted. "Fantasy bridges and cables to [Scotland] are delusional -- water, sewage, roads, rail, smart grids and getting us out of fuel poverty are what we really need."

In a letter to the Sunday Times, James Duncan, a retired offshore engineer in Edinburgh, noted that because of the water depth and distance a Northern Ireland-Scotland bridge would require 30 support masts each taller than the Eiffel Tower. He derided the idea is "as feasible as building a bridge to the moon.”

"No sane contractor or responsible government" would undertake its construction, Duncan's letter read.

The waters between Northern Ireland and Scotland are also plagued by rough seas and bad weather. In addition, in a trench called Beaufort's Dyke, the British military dumped surplus munitions — ranging from small arms to high explosives —after World War II. The U.K. Ministry of Defence estimated that more than 1 million tons of munitions are still at the bottom of Beaufort's Dyke. Such weapons often wash ashore on the Irish and Scottish coasts.

John Stewart, an Ulster Unionist Party member of the Northern Ireland Assembly, also criticized the proposal.

"Could a bridge be constructed that could withstand the weather and sea conditions in the North Channel [which links to the Irish Sea]?" Stewart said. "Secondly, what would be the cost and who would be putting up the cash? It would clearly be hugely expensive and would either be privately funded with tolls being charged for many decades to recoup the cost, or else require a serious amount of U.K. government funding.”

Stewart also questioned the need for such a bridge. "Given the poor state of so many roads in Northern Ireland, many people might prefer to see any resources that might be made available used to bring existing roads up to scratch."

While Sturgeon has not rejected the bridge proposal outright, she thinks there are better ways to more closely link Scotland, Northern Ireland and the Republic.

"I have representations made to me about the idea of a bridge; there are obviously a lot of challenges and things to be discussed there," she said. “We will always talk about how we can strengthen relations, we need to have practical and achievable ideas. Whether it’s around a bridge or in other ways strengthening the relationship between Scotland, the north of Ireland and the Republic of Ireland is a big priority for my government.”