BRIDGE TO THE PAST
Huge respect for the men who originally built the canals as we try our hands at 18th century-style bridge-building – it’s not easy
Our Deputy Ed tries his hand at 18th Century-style bridge building on the Cotswolds Canals
Intrados? Extrados? Queen closers? Okay, I’m an experienced canal restoration volunteer who’s laid a fair number of bricks over the last couple of decades (and I know what a queen closer is) – but this is something really rather different from what any of us are used to.
I’m with a team of Waterway Recovery Group and Cotswold Canal Trust volunteers at Weymoor Bridge – or rather at what was once Weymoor Bridge, and (hopefully) in the not too distant future, will once more be a traditional hump-backed canal bridge. At the moment, though, it looks like two large chunks of brick-faced abutment, one on each side of the silted-up canal channel and, in between them, a mass of scaffolding surrounding some large, curved steel girders. On top of these girders, a curved surface made up from wooden laths and plywood has been added. These, between them, form the ‘centring’, the temporary formwork upon which the bricks forming the arch are to be laid. And over the top of the whole lot is what looks suspiciously like the sort of marquee that gets used for outdoor wedding receptions (because that’s what it is!) to keep off the rain that’s threatening to dampen our spirits.
The volunteers’ job for the next fortnight is to lay the bricks to form the arch. I’m with the advance party of experienced volunteer bricklayers who’ve turned up on site a day early to try to get our heads around what we’ve already realised is a whole lot more complicated job than the typical straight lock chamber wall.
For starters, we’re laying it not as three separate rings of brickwork around the arch (as is common on canal bridges), but ‘fully bonded’ – like building a thick wall, but gradually tilting over as it approaches the crown of the arch. This, I am assured, will push up the strength of the arch from perhaps a seven-tonne weight limit to the 44 tonnes needed for the modern farm machinery which will