Boris Johnson's Channel Bridge plan 'absolutely possible', says one of world's leading bridge designers

Boris Johnson’s proposal to build a bridge across the Channel is “absolutely possible”, one of the world’s leading bridge designers has said.

Mr Johnson said it was "ridiculous" that the UK and France - two of the world's biggest economies - were only physically "linked by a single railway" as he floated the idea of building a road crossing.

The Foreign Secretary’s plan has been given a major boost after Ian Firth, senior vice president at the Institution of Structural Engineers, said building such a bridge was “entirely feasible”.

He told BBC Radio 4’s Today programme: “It has been looked at before. Before the tunnel was built there were bridge options being looked at and of course it is doable.

“There are bridges of a similar, but not quite that, scale elsewhere.

“We were looking very recently at a bridge between Denmark and Germany, again now being made as a tunnel, not as long but certainly of a similar sort of technical challenge.”

Critics have questioned the viability of building such a structure given the fact that the English Channel is the world’s busiest shipping lane.

But Mr Firth, chief operating officer at engineering firm Flint & Neill, suggested combining a bridge with a tunnel could avoid any impact on shipping.

He said: “There is no real issue particularly nowadays with modern technologies. We can design relatively long spans.

“This would be a multiple span structure. This has not got to be one big span of course.

“The economics may lean towards something like getting on for a kilometre spans or something, 800 metre to a kilometre span, that sort of size I would imagine. Multiple spans.

“It would be a huge undertaking but it would be absolutely possible and the shipping impact issues could be dealt with.”

Mr Firth would not be drawn on the possible cost of building such a 22-mile Channel Bridge.

The Foreign Secretary has previously championed the idea of a road tunnel under the Channel but believes a bridge might now be an option.

He hinted at his desire for more big Anglo-French infrastructure projects when he tweeted on Thursday: "I'm especially pleased we are establishing a panel of experts to look at major projects together. Our economic success depends on good infrastructure and good connections. Should the Channel Tunnel be just a first step?"

Mr Johnson is understood to have told aides: "We are two of the world's greatest economies linked by a single railway. It's ridiculous.

"Technology is moving on all the time and there are much longer bridges elsewhere, including one that is 34 miles long in Japan."

He believes the Channel Tunnel cannot provide the capacity which will be needed for increased tourism and trade between the two countries, and The Telegraph understands that he discussed a privately-funded bridge or tunnel link with his French counterparts.