Why DOES the Prime Minister think he can build a crossing from Scotland to Northern Ireland? 

There’s already one Giant’s Causeway in Northern Ireland, but if Boris Johnson’s latest unlikely wheeze comes to fruition, its windswept coastline may one day be home to a second.

In a bold, and some might say foolish, example of blue-sky thinking, the Prime Minister has asked officials at the Department for Transport to produce a ‘factual paper’ on the feasibility of building a bridge across the Irish Sea.

His big idea? To connect the outskirts of Belfast with Scotland’s mainland, offering the world a symbol of his forward-thinking nation’s economic vitality in the process.

Boris Johnson has asked officials at the Department for Transport to produce a ‘factual paper’ on the feasibility of building a bridge across the Irish Sea

This grand feat of engineering, dubbed the ‘Brexit Bridge’, will span up to 28 miles and according to current estimates cost anything from £15 billion to £20 billion.

It’s also an immense technical challenge. Critics, including one eminent engineer, have declared the chances of its proceeding without a hitch as ‘about as fanciful as building a bridge to the Moon’.

According to leaked briefing papers obtained by Channel 4, civil servants have nonetheless been told that the PM wants a detailed run-down of ‘the risks around the project’ not to mention a few ideas about ‘where this money would come from’.

In a country which seems incapable of building any new railway line, airport runway or major road either on time or on budget, this extraordinary endeavour seems optimistic to say the least.

After all, the most feasible of the two proposed routes must cross an often choppy stretch of water more than 1,000 ft deep.

The crossing would be adjacent to Beaufort¿s Dyke, a 900ft deep, 30-mile long trench which the Ministry of Defence previously used as a dumping ground for live munitions

The crossing would be adjacent to Beaufort’s Dyke, a 900ft deep, 30-mile long trench which the Ministry of Defence previously used as a dumping ground for live munitions

It would require dozens of vast support towers, roughly 1,400ft tall, to be built, transported on site, and then dropped with great precision and fixed firmly into the sea bed.

Adding to the perils, the crossing would be adjacent to Beaufort’s Dyke, a 900ft deep, 30-mile long trench which the Ministry of Defence used as a dumping ground for live munitions between the end of World War I and the Seventies.

More than 1.5 million tons of explosives — along with devices containing mustard gas and the nerve agent Sarin — are thought to be decomposing on the sea floor there, along with radioactive waste from Britain’s nuclear weapons programme. No complete map of their location exists.

The winds in the North Channel — the name for that part of the Irish Sea between Northern Ireland and Scotland — are notorious and can create threatening seas.

Indeed one of Britain’s worst sea disasters was here on January 31, 1953, when a British Rail ferry, the Princess Victoria, tried to make the crossing from Stranraer to Larne in raging winds.

She failed after the loading doors were stove in by huge seas and went down even as rescue boats tried to find her in atrocious conditions. A shocking 133 people died.

So can we be sure such a long bridge carrying high-sided lorries would survive such a storm?

Boris isn’t about to let such trifling questions derail the grand scheme, though.

‘The Prime Minister has made no secret of his support for infrastructure projects that increase connectivity for people and particularly those that strengthen the Union,’ was how a Downing Street spokesman put it this week.

One big reason for his support is, perhaps inevitably, Brexit.

According to leaked briefing papers obtained by Channel 4, civil servants have nonetheless been told that the PM wants a detailed run-down of ¿the risks around the project¿

According to leaked briefing papers obtained by Channel 4, civil servants have nonetheless been told that the PM wants a detailed run-down of ‘the risks around the project’

A bridge that physically connects Northern Ireland with the mainland has long been supported by Arlene Foster’s DUP, who regard it as a bold physical symbol of the link between Ulster and the rest of the UK.

Courting her party is, of course, crucial to Johnson’s ability to extricate Britain from the EU: though currently in coalition with the Tories, its stringent opposition to the so-called Irish backstop helped condemn Theresa May’s Brexit deal to defeat in the House of Commons earlier this year.

Importantly, the DUP reportedly believe that committing to build a bridge physically connecting the mainland with Northern Ireland might help solve the current impasse in Westminster by reducing the threat of a post-Brexit border across the Irish sea under any new deal — a fact that Johnson himself foresaw last year.

‘What we need to do is build a bridge between our islands,’ he declared, during an interview that was highly critical of Theresa May’s leadership. ‘Why don’t we? Why don’t we? There is so much more we can do, and what grieves me about the current approach to Brexit is that we are just in danger of not believing in ourselves, not believing in Britain.’

Meanwhile, in Scotland, where polls suggest there is much general hostility to Boris Johnson in advance of a possible UK general election, the idea is also hugely popular.

A bridge that physically connects Northern Ireland with the mainland has long been supported by Arlene Foster¿s DUP

A bridge that physically connects Northern Ireland with the mainland has long been supported by Arlene Foster’s DUP

Both of the proposed routes — either a 13-mile crossing from Torr Head in Northern Ireland to Scotland’s Mull of Kintyre (itself a long way north from most of Britain), or the 28-mile span from Larne to Portpatrick — will after all provide a fillip to the country’s somewhat moribund economy by strengthening trade with Ireland.

Perhaps that explains why even the SNP, whose stock reaction to new Tory policy proposals is immediate outrage, are also vigorously backing it. The Scottish Government’s constitutional relations secretary, Michael Russell, has called it a ‘great idea’.

The idea of creating a physical link between the UK and Ireland is nothing new, as it happens.

As far back as 1897, a group of businessmen from Belfast went to London to ask the British Government for £15,000 towards the cost of assessing the feasibility of a tunnel. No cash was forthcoming, but various similar proposals have been knocking around ever since.

Most recently, in the mid-2000s, engineering firm Symonds asked the Irish government to pay around £10 million towards a study looking at a tunnel project. It concluded that any such endeavour was unlikely to generate enough revenue to recover its costs.

The proposal the current project is likely to be based on has been drawn up by Alan Dunlop, Visiting Professor of Architecture at Robert Gordon University and Liverpool University.

He believes it could fuel a ‘Celtic powerhouse’ by allowing traffic to avoid expensive, and slow, ferry routes to the mainland.

‘One haulier I was speaking to was making dozens of trips across from Northern Ireland to Scotland every year and the cost of that was £600 each time,’ he has said. ‘So when you take personalised stories like this, you can see how the financial benefit would add up.’

Others aren’t so sure, though. Economist Dr Esmond Birnie of Ulster University, who has studied the economic impacts of a bridge, believes it would be unlikely to pay for itself in the long term.

‘Even on the most generous assumptions it is unlikely that the total measurable economic benefits of such a bridge would come anywhere close to its very considerable cost,’ he has argued.

In a country as divided as Northern Ireland, things are never entirely simple, though.

While the DUP are keen on building links with the mainland, their rivals in the nationalist community are anything but, raising fears that a ‘Brexit Bridge’ would become an immediate terrorist target.

2011 saw China open the Danyang¿Kunshan Grand Bridge, which takes rail traffic across an astonishing 102.4 miles

2011 saw China open the Danyang–Kunshan Grand Bridge, which takes rail traffic across an astonishing 102.4 miles

Yet the scheme’s biggest issues are not economic but practical. While many longer bridges have been built in recent years — 2011 saw China open the Danyang–Kunshan Grand Bridge, which takes rail traffic across an astonishing 102.4 miles — none has covered such a deep and hostile stretch of water.

Thailand’s 34-mile-long Bang Na expressway, the world’s longest road bridge, was built across dry land, while Europe’s current longest, the 10.7 mile Vasco da Gama, is in coastal waters near Lisbon. Its longest foundation piles go down a mere 311ft, roughly a third of the depth that would required to cross the Irish Sea.

Johnson, meanwhile, has form for ploughing public money into ill-fated bridges.

As Mayor of London, he became a vigorous proponent of actress Joanna Lumley’s so-called Garden Bridge across the Thames, even making a secretive trip to San Francisco in 2013 in an effort to get Apple to sponsor it.

Costs proceeded to spiral, while critics complained about the project being privately run yet publicly subsidised and argued that the scheme would become a costly white elephant.

Amid growing warnings that the Garden Bridge was likely to dramatically exceed its £185 million budget, with further concerns about its procurement processes, the project was shelved by Johnson’s successor, Sadiq Khan, in 2017. By then, the cost to taxpayers had reached an astonishing £43 million, with nothing whatsoever to show for it.

That failed bridge would have spanned a grand total of 30 metres, across a tidal river. Johnson’s ‘Brexit Bridge’ must, by contrast span roughly 45,000 metres of open sea — meaning that, on previous form, it’s heading straight for troubled water.

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