Architects and engineers have declared a bridge to France technically feasible – but questioned the cost and motivation of the project put forward by Boris Johnson
The foreign secretary is believed to have mooted the project to Emmanuel Macron during the French president’s visit to the UK this week.
The crossing is 20 miles at its narrowest and AJ sister title New Civil Engineer put the potential cost of a road bridge at hundreds of billions of pounds.
ReForm Architects managing director Nik Randall questioned the timing of the proposal as the UK looked to secure favourable terms for its exit from the EU.
‘It is important we are careful that this is not just a political project that is more symbolic than it is necessary,’ he told the AJ.
‘I am all for big ideas but it needs to show clear economic benefit. Would the benefits to the UK as a whole be greater with more bridges over the Thames or better rail links in the North?’
ReForm, which has registered designs for an east London crossing between the Isle of Dogs and Canada Water, said a bridge across the Channel may have to vary in height.
‘It is technically feasible, but this is the busiest shipping lane in the world and a bridge would have to keep shipping safe and unhindered,’ said Randall.
‘We have great architects and engineers in the UK and it would be a chance to show we are open. The Millau Viaduct, the tallest bridge in the world, was designed by English architect Norman Foster and French structural engineer Michel Virlogeux – so there are precedents in terms of scale.
‘It would be an exciting project but it would be important to engage the best ideas throughout the architectural community.’
It would be cheaper to move France closer to Britain
Alan Dunlop of Alan Dunlop Architects told Radio Sussex that although a bridge was possible, it was not necessarily wise.
‘It would be such a complex and difficult thing to do that it would be cheaper to move France closer to Britain,’ he quipped.
He said the world’s longest road bridge linked Hong Kong to Macau over a distance of 34 miles and took seven years at a cost of £120 billion.
Dunlop linked the latest proposals to the ill-fated Thames Garden Bridge – another grand projet backed by Johnson.
‘It is a bizarre idea and unfortunately Boris has a history of getting involved with bizarre bridge projects/ The Garden Bridge was a debacle. He should stay well clear of bridge projects.’
NCE technical editor Dave Parker told Radio Sussex there had been several previous proposals for a bridge between England and France.
‘The problem has always been worries about a supertanker ramming the structure, but by the time this bridge was built all major shipping will be autonomous so the risk would be quite low,’ he said.
One solution would be to tunnel the middle part of the bridge to allow ships to travel unaffected down the middle of the Channel, said Parker.
‘The Channel is not a major obstacle in terms of the depth to the bottom for foundations, the problem is the weather and who will fund it.’
Parker also said in NCE that post-Brexit restrictions on trade could make the bridge less viable.
Civil Engineering Contractors Association chief executive Alasdair Reisner said: ‘All great projects start as an idea that might, at first glance, appear unrealistic. As such, there is nothing wrong with putting forward even the most radical ideas for views from the public and wider industry.
‘However, we would hope that, at a time of tight constraints on public spending, any development funding for future infrastructure projects is directed to those with wide support and an outline business case that stands up to robust scrutiny.’
The idea of a bridge across the Channel is not new, having been mooted before. In the 1880s concept plans were drawn up for a railway bridge between England and France (see below).
Outline of a Channel Bridge from 1889