20 February 2012

Scottish Bridges: 18. Crathie Suspension Bridge

As with the Craigmin Bridge, I don't have any really good photos of the suspension footbridge at Crathie.

This bridge spans the River Dee in Aberdeenshire, just outside the grounds of Balmoral Castle. It was originally built in 1834 to carry carriages, to a design by John Justice Jr, although today it is open only to pedestrians. A wrought iron girder road bridge to Balmoral was built nearby in 1858 to a design by I.K. Brunel.

Justice was a highly innovative engineer, experimenting with variations on rod-stayed and suspension bridge form. His bridge at Haughs of Drimmie, Perthshire, combined a rod-stayed system with an under-deck suspension truss, while the earlier (and charmingly primitive) 1824 span at Kirkton of Glenisla, Angus, combined rod stays with shallow suspension bars incorporated into the parapets. Both are probably unique in their form, and it's amazing that they have survived to the present day.

As originally built, the Crathie bridge was very similar to the Haughs of Drimmie design, consisting of rod-stays supplemented by lightweight under-deck trusses. It seems I didn't take any photos which actually show the bridge in elevation, so you'll have to visit one of the links at the end of the post to understand what happens below the deck.

Although originally built as a "cable-stayed" design, the bridge was "renewed" in 1885 by Blaikie Bros., which is presumably when the iron flat link suspension chains were added.

Crathie Suspension Bridge is featured in several books, but astonishingly, Justice's other bridges are less well recognised. The Haughs of Drimmie bridge isn't even in Civil Engineering Heritage: Scotland, and none of these bridges are recognised in Walther's or Troitsky's books on cable-stayed bridges. It makes you wonder how many other remarkable bridges have escaped the attention of the historians.

With the other Justice Jr bridges, this is one of the earliest "cable-stayed" bridges built in the UK which still survives, although not the earliest unaltered example (that will be a story for another day).

Further information:

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