The Gaunless Bridge

Artefacts Of The S&DR

Despite severe weather late in 1823 when railway cuttings collapsed, quarry tracks became quagmires, and workmen were injured, George Stephenson was able to report in December to the Stockton & Darlington Railway Company that the river Gaunless between St. Helen Auckland and West Auckland, had been spanned in October by the iron bridge designed by him and cast by Burrell and Company of Newcastle.[1]

George Stephenson was a partner in Burrell’s until the 31st December 1824 [2] and so he already had a close working relationship with this company. Further, the new company established for George Stephenson’s son Robert, by the key financiers of the S&DR, – ‘Robert Stephenson & Co’, would be located next door to Burrell & Co in 1823. Burrell and Co. worked to a design submitted by George Stephenson and approved by the directors of the S&DR on the 28th December 1822.

But disaster struck! Heavy snow in the winter of 1823-4 followed by flooding when the thaw came, damaged the bridge badly and so Stephenson had to rebuild it with an additional span taking it to four spans which would allow more space for floodwater to pass under.

The bridge came into use when the line was opened on 27th September 1825.  From the outset it was assumed that the waggons using it would be hauled by horse rather than locomotive, because its location was on level ground between two incline planes. So waggons would be unhitched at the foot of Etherley incline, attached to horses, hauled over the Gaunless bridge and then delivered to the foot of Brusselton incline where they would be attached to rope again and hauled up the hill and down the other side to New Shildon where the locomotives would be waiting.

While the abutments were made of stone with graceful curved wing walls terminating in pepper pot copes, the truss below the decking and the supporting pillars were made of a combination of wrought and cast iron. It is the first bridge for our modern railway network to use an iron truss and the lenticular design of the truss is extremely unusual.[3] Stephenson’s sound grasp of engineering resulted in a clever technical symmetry between tension and compression.

Walkways for railway workers leading horses were cantilevered out from the sides of the decking.  The use of additional iron pillars at the end of the bridge meant that it was a self-supporting structure, even without the stone abutments.

Truss bridges were popular and are still used today because they use small amounts of materials but can carry a heavy load. However most truss bridges will have the metalwork (or indeed woodwork) arranged in triangular shapes, not the lenticular shapes you see at the Gaunless Bridge. So this particular design didn’t really catch on.

It was adapted however, and used by Brunel in 1854, on his much bigger Royal Albert Bridge across the Tamar, but his decking was below the truss.[4] It was also adapted for use at the Saltash Railway Bridge near Plymouth in 1859 and the five Elbe Bridges near Hamburg built in the period from 1872 – 1892.[5]

Closer to home, Escomb Railway Bridge (No. 12), built in 1842, uses an interesting design in the form of a bow-sprung single span, laid on a skew and carrying a farm track which bears some resemblance to Stephenson’s design. It was built by the Shildon Works Company, in conjunction with John Storey of Darlington, for the Bishop Auckland and Weardale Railway Company and like the Gaunless Bridge, was made from a combination of cast and wrought-iron and with timber.

There are therefore not many such iron truss railway bridges in the world and the Gaunless is the earliest. Or is it?

There is a competitor to this claim at the Pont-y-Cafnau (English: Bridge of Troughs). This is an iron truss bridge over the River Taff and was designed by Watkin George and built in 1793 for his employer, the Cyfarthfa (Cifarthfa) Ironworks. However it was designed to support both a tramway and an aqueduct to carry limestone and water into the works and so it is debateable whether it was accommodating a railway in the modern sense.[6] Certainly it bears very little resemblance to Stephenson’s lenticular truss.

The Gaunless Bridge therefore has some claim as the first purpose built railway bridge made of iron in the world. [7]

The bridge remained intact until 1901 when it was dismantled, so that an alternative structure could be placed on the abutments which would accommodate heavier loads of coal. The trestle legs were cut off at river level and the superstructure moved to Brusselton Colliery for storage.

The two stone abutments remained on either side of the river Gaunless.  The original ironwork was preserved, however, and featured in the 100th anniversary celebrations in 1925. When a railway museum opened in 1927 at Queen Street in York, the ironwork was one of the indoor exhibits running down the centre of a large hall.

The ironwork was moved to the National Railway Museum in York in 1975. When first erected there, it was overlooked by the museum cafe but a later reordering of the layouts inside the museum left the bridge ironwork largely out of sight to most visitors.

As the 200th anniversary of the S&DR approached in 2025, the NRM decided to move the structure from York to Shildon, having first had it conserved. In doing so they confirmed that it was built without rivets or bolts and simply clicked together and that the first layer of paint over the undercoat was green and cream.

You can listen to a podcast about the Gaunless Bridge and the Skerne bridge here.

[1] Rolt 2012 and contra http://www.engineering-timelines.com/scripts/engineeringItem.asp?id=15 which states that it was complete by October 23rd 1823.

[2] Tomlinson 1987, 93. His son Robert was also managing director

[3] J. G. James in the Transactions of the Newcomen Society vols 52 and 59 and cited in Addyman and Haworth 2005, 13

[4] ibid

[5] Tomlinson 1974, 108 and http://www.009.cd2.com/members/how_to/bridge_development.htm [accessed 16122015]

[6] https://en.wikipedia.org/wiki/Pont-y-Cafnau [accessed 14122015]

[7] Acc No. 1978-7189