Dandry Mire is a relatively small area of peatland at Garsdale Head, where the watershed of the Rivers Clough and Ure forms a relatively low-level pass between Garsdale and Wensleydale. The original plan for the Settle & Carlisle Railway involved crossing over the trans-Pennine road via a single skew arch (Moorcock Bridge), then crossing the mire via an embankment. The embankment would be constructed using the spoil excavated from nearby Moorcock Tunnel and its approach cuttings, so this was expected to be a relatively cheap and efficient use of both materials and labour. However, the reality was somewhat different to the plan.
Every day for two years, the contractors used 100 tip wagons to move rock & earth from the cutting to the site of the embankment, but the mire had a voracious appetite and consumed almost everything that was tipped into it. The situation is vividly described by the contemporary author F.S. Williams[1]:
But the peat yielded to the weight placed upon it, and rose on each side in a bank, in some places fifteen feet high. After more than 250,000 cubic yards had been tipped, it was decided that a viaduct of twelve arches over the deepest part of the works must be made. The work thus erected is some fifty feet high, and for nearly the whole length it had to be sunk an additional fifteen feet through the peat before a firm foundation could be obtained.
The result is this 227 yard (207 metre) long, gently curving gritstone viaduct, flanked by two relatively short sections of embankment.
- For strength and resilience, the viaduct is split into three 4-arch sections and the piers between each section (pier numbers 4 & 8) are significantly thicker than the intermediate piers.
- The arches vary in diameter from 44 feet 3 inches to 45 feet.
- Since its construction (1873-1875), this Grade II listed structure has been stabilised with numerous rock bolts and spandrel ties and two of the piers towards the north end have been strengthened with concrete & steel 'jackets'. Guard rails have also been added along the top of the parapet walls to protect railway workers from a potentially fatal fall.
