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Balmoral Bridge (Crathie Girder Bridge)
Crathie, east of Braemar, Aberdeenshire, Scotland, UK
Balmoral Bridge (Crathie Girder Bridge)
associated engineer
Isambard Kingdom Brunel
date  1856 - 1857
era  Victorian  |  category  Bridge  |  reference  NO261949
ICE reference number  HEW 1070
photo  Alan Cooper
Commissioned by the royal family as part of improvements to the Balmoral Estate, the final appearance of this austere but robust single span plate-girder bridge across the River Dee did not entirely meet their approval. However, it is probably the first of its kind in Scotland and Brunel’s only bridge there. Recently refurbished, it remains in use and is now Category A listed.
In 1852, the Balmoral Estate and its 15th century castle were purchased privately by Prince Albert for Queen Victoria. The present Balmoral Castle (NO254950) was completed in 1856, some 90m north of the original building (NO254948), which was considered too small. The estate does not belong to the Crown and remains the royal family’s private property.
In 1854, as part of a programme of new works at Balmoral, Prince Albert commissioned Isambard Kingdom Brunel (1806-59) to construct a new carriage bridge over the River Dee to join with the main road (now the A93) along the north bank of the river. The existing vehicular access to the estate was over the slender wrought iron Crathie Suspension Bridge (1834).
The bridge Brunel produced was designed to support a load of 87 tonnes and still capable of bearing the weight of modern traffic. His sketches of November 1854 show that two designs were considered, and that the option not selected appears similar to Royal Albert Bridge over the River Tamar (1853-9) at Saltash, Cornwall.
Construction of Balmoral Bridge commenced in 1856. It crosses the river in a single span measuring 38.1m between abutments, offering no impediment to the often fast-flowing waters below. The 5.5m high abutments are founded on rock. They are made of coursed granite with capped square pillars and curved approach walls.
The main structural elements are the two horizontal wrought iron plate girders on either side of the bridge deck. Each is 39.6m long and 2m deep. Brunel incorporated five 102mm diameter roller bearings beneath the mounted ends of the girders at the east end, and used an innovative girder section designed to resist buckling.
His stylish touch can be seen in the convex flanges to the girders, 660mm wide at the top and 838mm wide at the base. The upper parts of the girders have a pattern of diagonal web plates, giving a lattice effect along the parapets. Four pairs of intermediate stiffeners are provided per girder, at 7.6m centres. Distinctive visible riveting adds decorative detail.
The roadway is 4m wide between the plate girders and has no footway. It runs over a timber bridge deck carried on 305mm deep plate cross beams, at 4.6m centres.
The ironwork was fabricated at the Railway Works of Rowland Brotherhood (1812-83) in Chippenham, Wiltshire, and transported to site for riveting in situ.
Balmoral Bridge was completed in 1857, but apparently its functional appearance did not find favour with Queen Victoria and Prince Albert, who perhaps wished for something more ornate.
In 1971, the original longitudinal pine decking was renewed. The planks now have a tarmac surface, of single carriageway without markings/signage. The bridge carries the B976 road. In November 1976, the bridge was listed as Category B. In May 1994, the designation was upgraded to Category A listing.
On 29th May 2006, in the bicentenary year of Brunel’s birth, an Institution of Civil Engineers commemorative plaque was unveiled on the bridge by Prince Philip.
In October 2011, bridge deck repairs were undertaken, owing to timber deterioration. The end bays of the deck were propped between the main girders, pending further intervention.
In December 2013, Aberdeenshire Council and Historic Scotland gave planning approval for a £450,000 programme of repair work. The strengthening and refurbishment works commenced on 8th October 2014. The bridge deck was reconfigured, with its timber planks replaced by reinforced concrete, without altering Brunel's ironwork. The bridge was also repainted.
On 20th February 2015, Balmoral Bridge was re-opened in a ceremony attended by Jill Webster, Provost of Aberdeenshire.
Supervising engineer: Dr Andrew Robertson, Balmoral Estates Factor
Ironwork: Rowland Brotherhood of Chippenham, Wiltshire
Research: ECPK
reference sources   CEH SHIHighBr

Balmoral Bridge (Crathie Girder Bridge)