Maintaining a bridge between Scotland and Northern Ireland would be an even greater challenge than building the “colossal structure”, an engineering expert has warned.

Dr Luke Prendergast, assistant professor in civil engineering at the University of Nottingham, said a bridge across the Irish Sea would face “significant” risks to damage.

Research is being carried out into the feasibility of a bridge or tunnel as part of Prime Minister Boris Johnson’s bid to improve UK transport links.

Dr Prendergast described the depth of water, up to 160 metres, and the presence of dumped munitions as “major barriers” to building a bridge.

“However, concerns over the ease of construction pale into insignificance compared to the greater challenge of the upkeep of such a colossal structure,” he said.

“Bridges require near-constant maintenance to ensure they remain safe, and the risks to one that spans 28 miles across the sea are significant.

“Storms, rough waters, ship impacts, corrosion from the harsh salty environment all have the potential to seriously damage this engineering feat.”

Dr Prendergast explained that bridges “are never built to be permanent”, and the amount of time they remain open can be “drastically cut short depending on the degradation faced over the years”.

He added: “The eye-watering cost of maintaining a 28-mile long bridge is also a point to consider.

“In the event the bridge requires closure for repairs, for instance, what alternative transport routes would be in place and who foots the bill?”

Chris Richards, director of policy at the Institution of Civil Engineers, said it was important that the “need” for a bridge linking Scotland and Northern Ireland is analysed, alongside its feasibility.

He commented: “A technical feasibility study is the right approach for any proposed major infrastructure project.

“We await the outcome of that study which should allow the right discussions about feasibility, cost, and whole-life benefits to be considered.

“A wider study on ‘need’ should also be undertaken before a decision is made. It is important that all major infrastructure projects be considered in a holistic and strategic way, as at their core they must address a societal need.”