RAILWAY bosses have announced plans to install safety measures in the longest tunnel on one of the North’s most beloved railway lines to avoid a repeat of a terrifying derailment in which a 70mph passenger train hit a colossal block of ice.

Network Rail has applied to North Yorkshire County Council for permission to install ice prevention covers over three tunnel shafts along Blea Moor Tunnel, near Ribblehead viaduct in the Yorkshire Dales, on the Settle to Carlisle Railway.

The 1.5-mile tunnel, which took almost five years to build before being completed in 1875, passes some 500 feet below the moor after which it was named and historians have claimed it was used to test steam locomotives.

It was built with the aid of seven huge construction shafts sunk from the moor, permitting 16 gangs of workers to be used during construction, three of which remain for ventilation.

However, Network Rail said solid covers are needed for the shafts to prevent the rainwater pouring down, leading to ice forming on the inside of the tunnels, which has caused train derailments.

In 2010, a TransPennine Express from Manchester Airport to York with 45 passengers hit a 2m by 8m block of ice in Summit Tunnel, Calderdale, but it remained upright, bouncing along the tunnel wall before coming to a stop.

At the time passenger Brenda Duthoit, 62, said: “I held on to the seat in front and thought the train was going to roll over, then there was a horrible grating noise which was presumably the train hitting the side of the tunnel.”

After the incident the Railway Accident Investigation Breanch sait was aware of a number of incidents” involving ice in tunnels and reviewed Network Rail’s arrangements for cutting risks over ice-related hazards in tunnels.

Network Rail said while action was needed as it had found “ice chandeliers within the tunnel”, and the work would require the dismantling of a number of courses of brickwork on the huge shafts, which will be rebuilt.

It added the work would be carried out sensitively as the shafts were in a designated special site of scientific interest, as well as the Yorkshire Dales National Park and the the railway’s own conservation area.

While the public body has the right to carry out the works under the line’s own legislation - the Midland Railway (Settle to Carlisle) Act 1866 - it must get planning consent to alter existing structures.

The planning application has been lodged just weeks before Network Rail launches “interventions” at the nearby Ribblehead viaduct to secure its future for decades to come.

The 144-year-old viaduct, described by the public body as one of the crown jewels of Victorian civil engineering, will have its drainage improved and brickwork restored making journeys for passenger and freight trains more reliable on the line.

The Great North Rail Project work will start in July and will see an investment of £2.1m in the Grade II listed structure.

No major disruption is expected for passengers using the railway line during the viaduct’s 2020 maintenance.