Causey Arch

15th century Aldin Grange Bridge spans the River Browney near Bearpark, County Durham © Metaforz Photography 2013

The Causey Arch (or Tanfield Arch as it was also known) is thought to be the world’s first railway bridge and was constructed to carry a waggonway taking coal from nearby Tanfield Colliery to the staithes on the River Tyne 5.5 miles away. It was built in 1727 and spans the steep gorge over the Causey Burn near Stanley in County Durham (it superseded an earlier bridge built in 1725 that had collapsed almost immediately). A consortium of local coal-owners known as the “Grand Allies” commissioned stonemason Ralph Wood to build it for them at a cost of £12,000. At 105′ wide and 85′ high it was the largest single-span bridge in the country for 30 years. The Causey Arch was built as a toll-bridge and the toll-house itself was located at the west end of the bridge.

Waggonways were horse-drawn railways that were developed in the early 17th century to avoid having to use the poorly maintained roads of the time. At first, the rails were made of wood but wore out very quickly. Two separate tracks were laid: a ‘main way’ that carried the fully laden waggons and a ‘bye-way’ for returning waggons. The rails had a gauge of between 4′ and 5′ and thanks to George Stephenson were responsible for the modern railway gauge of 4′ 8″. As might be expected, the ‘main-way’ rails tended to wear much more quickly than those of the ‘bye-way’, a problem that was only resolved on the Tanfield Way when wooden rails were replaced by iron in 1839.

The heavy waggons contained a ‘chaldron’ of coal which was the measure in which it was traded and was equivalent to 2.65 tonnes (the replica pictured left is located at the east end of the bridge). They were pulled by a single horse: the ways were engineered to be level or downhill to the staithes so that the horses would only have to pull empty waggons uphill. They travelled downhill under gravity retarded by the horse and by the primitive wooden brakes (the lever of which can be seen on the left). Brakes and wheels frequently caught fire due to the heat generated. It is thought that at its height over 900 waggons crossed the Causey Arch each day but this declined markedly when Tanfield colliery was burnt out in 1740.

Not far downstream from the Causey Arch is another much less obvious feat of Georgian civil engineering: the gorge is spanned again, this time by a massive embankment 1300′ long and 90′ high, covering a culvert through which the burn flows. The collossal amount of material required to build it was taken from the cuttings that were necessary to ensure that the gradient was always shallow enough for the horses. This all had to be moved by hand and barrow and is a testimony to the industry of the navvies who were brought in to do the job.

Pictured at the top of the page is the Causey Arch from the south-east side.

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