Johnson’s plan for Irish Sea bridge or tunnel rejected by official study | Transport policy

Boris Johnson’s proposal for a bridge or tunnel linking Scotland to Northern Ireland has been rejected by a feasibility study as vastly costly and fraught with potential difficulties.

Released alongside a wider so-called union connectivity review, which known as for funding in highway, rail and home aviation to raised join the 4 UK nations, the fixed link report discovered both a bridge or tunnel could be on the very fringe of what might be achieved with present know-how.

The estimated price for the bridge could be £335bn and £209bn for the tunnel, with the latter solely capable of accommodate trains for security causes. It would take at the very least 30 years for both of the hyperlinks to open.

A specific drawback, which was raised by engineers when Johnson proposed the hyperlink in 2019, is Beaufort’s Dyke. The seabed trench is as much as 300 metres deep and greater than two miles extensive at its broadest level, and can also be stuffed with million tonnes of munitions dumped within the Nineteen Seventies.

A tunnel must be development at depths of about 400 metres beneath water stage, exerting vital pressures and requiring a 25-mile climb in both route given a most rail gradient of 1 in 100.

By comparability the Channel tunnel is simply over 23 miles lengthy, with a most depth of 75 metres.

Beaufort’s Dyke would additionally show “a challenge” for the bridge as a result of the development must go over the ditch, with a span of at the very least 2.5 miles and foundations set again from the sting, mentioned the study, which was led by a small group of civil engineering consultants.

No suspension bridge with a span that lengthy has but been constructed, the report mentioned, though there have been some design ideas with related lengths.

In an introduction to the feasibility report, Sir Peter Hendy, the chair of Network Rail, who led the connectivity review, mentioned the study had concluded each initiatives had been attainable.

“A bridge crossing, however, would be the longest span bridge built to date,” he wrote. “A tunnel would be the longest undersea tunnel ever built given the limited gradients on which trains can operate, the route it would need to take and the depths it would need to reach.”

Building a rail hyperlink would additionally create “some complexity” as a result of the monitor gauge in Northern Ireland is similar as within the Republic however completely different to that in the remainder of the UK.

Hendy, who headed Transport for London when Johnson was mayor of town, nonetheless mentioned it had been “excellent question to ask”.

He wrote: “For many decades, politicians and engineers have debated this proposal, but have done so without the evidence to show whether it was possible and, if so, what it would take to do it. This is the first comprehensive, conclusive study on the subject since the idea was first mooted over 150 years ago.”

Johnson has a combined report on proposals for formidable bridges. As mayor of London he spent at the very least £37m of public money on a deliberate backyard bridge over the Thames regardless of worries over funding, the project’s goal and the shortage of planning consents on one facet of the river.

Among concepts within the wider connectivity review had been funding within the west coast railway line north of Crewe to present higher hyperlinks to Scotland, one thing which fits past the £96bn rail plan introduced final week, and an improve to the A75 highway, which runs from the M6 close to Gretna Green to the Scottish ferry port of Stranraer.

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