Our most-recent update is very cycle-friendly, looking at four structures which have been rehabilitated to host shared paths in recent years.

Although Tregarth Tunnel in North Wales is modest in length, it boasts a dramatic constructional history. In March 1885, five navvies were consumed by a fall of rock and brickwork following a period of heavy rain. Despite rib injuries, 35-year-old Roland Evans was able to walk back to his lodgings; however he soon succumbed to an internal haemorrhage. And two years earlier, 25-year-old Isaac Jones had both legs blown off when preparing dynamite.

The excavation of St Fillans Tunnel - visited by K-Burn when it was still fenced off - frightened the local dog population but had no known fatal consequences for its miners; in fact it didn’t even need supporting timbers. Like many structures along the Lochearnhead, St Fillans and Comrie Railway, it was built using mass concrete due to the dearth of alternative materials locally. Although stone is unquestionably more attractive, they went to considerable effort to make the concrete blend in.

Jon Tuckett has crossed the River Taw bridge which Barnstaple Town Council felt sure would be an eyesore when it was first mooted. But Colonel Rich complimented the contractors for the manner in which the work had been undertaken when he subjected the bridge to severe testing on behalf of the Board of Trade. Three coupled engines, each weighing 40 tonnes, were left to stand over two of the piers for almost an hour with no appreciable deflection.

Calder Viaduct near Castleford has definitely moved, its eastern abutment no longer being aligned with the rest of the structure. There are cracks and bulging. But masonry structures have redundancy built in and are not prone to sudden catastrophic failures; all is generally well with it thanks to a collection of tie bars and pattress plates. Tarmac has been laid across its deck as part of a scheme - not yet fully realised - to create cycle paths at both ends.

If you’re not sure what an abutment is or can’t visualise a pattress plate, we have responded to the requests of many folk to publish a glossary of engineering terms. If you disagree with our definition or think we’ve missed one, please get in touch. It’s very much a work in progress.