There are hundreds of old railway bridges much like the one at Great Musgrave in Cumbria’s Eden Valley. The structure emerged from the ground in 1861 through the courage of a few men and perhaps a horse or two, toiling in conditions we can’t begin to imagine. Over 160 years, it became woven into the fabric of the village - a valued part of its history and landscape.

Then, one day, National Highways (NH) turned up and started to bury it in 1,644 tonnes of aggregate and concrete. Not a prior word to the Parish Council or the local highways authority, and no consultation either with the two heritage railways whose longstanding ambition to reunite involved relaying a track beneath the arch.

This was an inexplicable act, unjustified from every conceivable perspective except the narrow one of opportunistic liability reduction. But as the state-owned roads company found itself embroiled in a storm, it constructed an alternative reality which only made matters worse.

A question of strength

In 1998, Cumbria County Council commissioned an assessment of structure EDE/25, known as Great Musgrave bridge. It showed a few modest defects, but the values assigned to mortar loss and profile were overly conservative, resulting in an assessed capacity of just 17 tonnes. More appropriate values would have lifted the modified axle load from 7.5 tonnes to 15 tonnes, well in excess of the 11.5 tonnes needed for a 44-tonne vehicle. To restore the bridge to full capacity, repointing of the arch barrel was recommended.

Repairs were undertaken in 2012 - although it’s not clear that any work to the arch took place - and a Detailed Examination followed in 2017. The latter recorded some mortar loss and displacement of individual stone blocks in the arch by up to 4mm, but the structure’s condition was described as Fair, whilst National Highways’ scoring matrix identified “No significant risk”.

The 2020 visual inspection suggested the maximum deflection of soffit stones was now 15mm (or 3% of their depth). Recording the movement of masonry blocks to supposed millimetre accuracy using a tape measure held by an inspector standing on the ground is futile: the margin of error is too great.

But again, the bridge’s condition was Fair and “No significant risk” was presented. A year later, the examiner made clear that “the bridge appears to be in Fair condition” and notes “Changes to Existing Defects since Last Examination – None”; however the scoring matrix indicated “High” risk to the public with “Medium” likelihood of occurrence. This sudden and significant change to the perceived risk level was recorded after the bridge had been infilled and had no foundation.

In 2022, National Highways’ retrospective planning application for retention of the Great Musgrave bridge infill - an obligation imposed by Eden District Council (EDC), the Local Planning Authority - claimed that, since 2017, “the joints between the masonry in the arch had again opened up (to 170mm) and that the crown of the arch had dropped (by 15mm)”.

These statements were misleading: the 170mm figure referred to one isolated perpend joint of no structural consequence, whilst the asserted movement of the arch actually related to a small number of individual stone blocks. The inconsistent method and location of the measurements taken by National Highways’ examiners meant there was no evidence of any worsening of their displacement, an observation supported by the lack of any visible clean stone around their edges. It’s likely some of them had only moved 160 years ago when the timber centring was struck following construction.

Fundamentally, Great Musgrave bridge was fine and contacts within Network Rail suggest they would not have looked twice at it, based on the available engineering reports.