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Crathie Suspension Bridge (Balmoral East Bridge)
Crathie, east of Braemar, Aberdeenshire, Scotland, UK
associated engineer
John Justice Jr
date  1834, 1884 - 1885
UK era  Georgian  |  category  Bridge  |  reference  NO265942
Crathie Suspension Bridge over the River Dee was constructed to provide carriage access to Balmoral Castle, the private residence of the British monarch. In later years, vehicular traffic was transferred to the more robust Balmoral Bridge and this one was retained for pedestrians. It is Category A listed.
The bridge was erected originally in 1834, by John Justice junior, from the Justice family of blacksmiths in Dundee. It is one of several early lightweight iron suspension bridges constructed by Justice & Co. in north east Scotland. Others still in existence include Kirkton of Glenisla (1824) and Haugh of Drimmie (c.1823). All are characterised by the somewhat ad hoc nature of their slender superstructures.
When completed, Crathie Suspension Bridge was the main approach to nearby Balmoral Castle (NO254948), replacing the local ferry. It spans 41.8m between granite masonry piers with rounded cutwaters and a flood relief arch on the north and south banks of the River Dee. Above deck level the piers are stepped, with plinths to both sides of the road, 1.7m by 1.6m in plan.
The plinths support open lattice towers, two at each end of the bridge, connected at the top by decoratively arched frames across the roadway. The legs of the A-frame towers are 1.2m apart at the base and 360mm apart at a height of 4.6m. The legs are of flat wrought iron plates, giving a 102mm square section, and are braced horizontally with 51mm by 38mm flat bars and diagonally with 38mm square rods.
The bridge deck is carried by inclined stays and catenary chains. It has four wrought iron stays at each tower, connected in pairs at each of two points on the upper part of the legs. The main suspension chains are carried on saddles 5.4m above deck level and have a dip of about 4.2m. The chains consist of pairs of bar links, 64mm by 12mm in cross section and 4.5m long, with short vertical links of 203mm to the hanger tops fashioned in ‘turnbuckle’ connectors in the centres of the links between bars. Hangers, 22mm in diameter, are suspended from the short links and from the third points of the long bars, at 1.5m centres.
Each pair of hangers is connected transversely below the deck by a bowstring four-panel open lattice beam of square wrought iron bar. Two longitudinal bowstring trusses add further stiffness below the transverse beams, though it’s not clear whether or not they may have been added later. The transverse beams support the four longitudinal timber beams that carry the transverse timber deck planks.
The bridge is 3.8m wide between hangers. On either side of the deck, wrought iron railings 1m high are fixed to the top of a 102mm square longitudinal timber runner. The railings have longitudinal bars 32mm by 10mm at top, half-height and base, with vertical 16mm diameter rods at 152mm centres. A 'kissing gate’ of similar style is located at each end of the approach, beside the carriageway. All the ironwork is painted white.
In 1854, Isambard Kingdom Brunel (1806-59) examined the bridge structurally while he was in the area for the construction of his Balmoral Bridge to the north west. Prince Albert had bought the Balmoral Estate in 1852, and commissioned much new work. Brunel advised Queen Victoria’s representative that "I believe you may consider it [Crathie Bridge] perfectly safe for all ordinary loads tho' quite unfit to bear a crowd of people or a drove of cattle".
In 1884-5, the bridge was "almost entirely renewed" at the Queen’s expense. Some diagonal bracing was installed in the trusses below deck, though few of these ties remain in place now. The extent of the renewal work at and above deck level is not clear. Sources differ on whether the inclined stays or the suspension chains, or both, are original.
Vehicular traffic crosses the river on Balmoral Bridge and Crathie Suspension Bridge is used only by foot traffic. In November 1976, the bridge was designated a Category A listed structure. In 1989, its timber deck was replaced.
Construction: Justice Junior & Co of Dundee
reference sources   HighBr

Crathie Suspension Bridge (Balmoral East Bridge)