Newport's Town Bridge
John Nash's Design for Newport Bridge (1791-2)
By Peter Brown
As the 18th century drew to a close, the authorities began to investigate the options for replacing the timber bridge with a durable one built of stone. Eventually a public meeting was held at Usk on the 18th September 1789, where it was agreed to seek the authority of Parliament to use the county rate to erect a new bridge at Newport.[1] The bridge committee invited designs for the bridge and in competition with three other submissions, the architect John Nash was engaged. Nash is perhaps the best-known architect of his generation, but is less well known for his work in Wales or as a bridge builder, although he built the bridges at Trecefel and Aberystwyth in Cardiganshire.[2]
In 1791, Nash submitted plans and a model to the Monmouthshire justices which gave ‘great credit to his geometric talents’[3] and proposed the construction of an arch bridge[4] that would have crossed the river in one span. These plans have since disappeared, but we are fortunate to still have the drawing for the timber centring needed to construct the arch and this precise drawing affords a great deal of information about the bridge itself.[5] From this we know that it would have had a span of roughly 285’ (86m), making it the largest single-arch bridge ever constructed at that time, more than doubling the span of the contemporary world-record holder at Pontypridd, only about 20 miles away.
A set of accounts reveals the expenditure on the bridge between 1 August 1790 and 23 July 1793.[6] On 13 Oct 1791, Mr John Dodford was paid £30 ‘for his plan expenses etc’. Mr Nash was paid £700 5s 10d ‘…his Acct for a Model, carriage, Journeys, work materials, drawing, estimates, commission, expenses etc as by particulars in the first A/c appears’. Mr Uzzell was paid £32 19s for his plan and estimate, while other sums were paid for adverts in the Gloucester Journal and the Bristol Gazette.
With no supporting piers needed, the bridge required substantial abutments in the riverbanks and due to the tidal range, it proved impossible to find contractors willing to take on such a bold venture. Nash carried on himself and began constructing a coffer-dam, but in May 1792 the scheme was abandoned following a ‘county meeting of gentlemen and freeholders called by the clerk of the peace’.[7] Nash was paid off with £700 for the work already completed and a new design was sought. The reasons why the scheme was discontinued are not recorded, but it seems that the ambitious design presented too many risks for the justices, who had eagerly embraced the bold design the previous year. The project would have given the town the greatest bridge on earth, but the opportunity for such fame was lost for Newport.
The structure of the bridge
Nash’s design for the bridge at Newport was nothing less than revolutionary, by crossing such a wide river without the need for supporting piers. The bridge was an arc of a circle of 310’ (93m) in diameter and with a span of roughly 285’ (86m). The crown of the centring stood about 100’ (30m) from the low water level and as the tidal range is around 42’ (13m), this still left roughly 58’ (17m) between the high-water level and the crown. Above the crown, the bridge structure would have added at least another 7’ (2m). This was a gigantic structure that would have towered above the river next to the castle.
Diagram for the centring of Nash's bridge.
Reproduced by kind permission of Gwent Archives. (Reference GRO Q/CB 0001/1)
There were few precedents for Nash to follow in this design, but the one that must surely have been a major influence was the famous bridge at Pontypridd, built by William Edwards in 1756 and which had a span of 141’ (42m).[8] This is our best example to imagine the design that Nash drew for the Newport bridge and it deserves close inspection. The bridge is light and elegant and has stood the test of time, unlike Edwards’s three earlier attempts at the same site. The width of 11’ (3m) was adequate for its day, but the steepness of the roadways meant that waggons and carriages needed to use a ‘chain and drag’ system to descend from the crown. The method was described in the following way in 1838.[9]
“When a carriage reaches the centre of the bridge, one end of the chain is attached to the hinder part of it, the other being secured to the drag, upon which a boy generally places himself, so that as the carriage descends upon one side the drag is pulled up the other, and this relieves the horse in descending.”
Pontypridd bridge built by William Edwards (1756)
Without the diagrams we cannot be certain of the design of the Newport bridge, but the indications are that due to its size similar problems would have occurred, although this could have been alleviated to some degree by adding built-up approaches with more manageable gradients. Standing on the Pontypridd bridge today, it is still difficult to picture a bridge more than twice that size, yet the records confirm this for Nash’s design.
When the Pontypridd bridge was built it was the largest single-arch bridge in the world, but it was not the biggest ever built, for that honour belonged to the bridge at Trezzo in Italy, completed in 1377, but slighted in 1416.[10] That bridge had a span of 239’ (72m) and perhaps as much as 252’ (76m), though it was still smaller than Nash’s design and no stone bridge anywhere exceeded the span of the Newport bridge until the 1905 Plauen bridge in Germany at 295’ (90m), while this was superseded in 1919 by the bridge at Villeneuve-sur-Lot in France, with a span of 315’ (96m). According to Wikipedia, only six further masonry bridges have ever been built that exceed the span of Nash’s proposed bridge at Newport; these are all in China and built since 1961, with the largest measuring a staggering 479’ (146m).[11]
Our impression of what Nash's bridge could have looked like, with a single span of 285 feet (87m)
- double that of the existing world-record holder (Pontypridd, 141 feet - 43m).
Image based on a print by Pugh (c1806), Nash's original plans for the timber centering
and a scale drawing of Pontypridd Bridge.
Before leaving Nash’s bridge we should note that his ideas were picked up elsewhere soon afterwards, as a committee was formed in Sunderland to promote the construction of a bridge over the mouth of the river Wear, at the same time as the Newport bridge plan was active. Following the halt of Nash’s project, his plans were considered along with others by the Sunderland committee,[12] which discussed whether to build one arch or two, with the option of a single-arch bridge of more than 200’ (60m) that would have been smaller than Nash’s design, yet still set a world record. Eventually they chose an iron bridge with a single span and pushed the boundaries of the new technology afforded by the developments in iron production, spearheaded by the first iron bridge ever built at Ironbridge, Shropshire, in 1779. The Sunderland bridge opened in 1796 and was acclaimed as the world’s largest single span bridge at 236’ (71m), but even with the advantage of iron framing, it was still 50’ (15m) smaller than Nash’s design for Newport. The promoters at Sunderland were rewarded with the accolade that should have come to Newport, had the Newport justices shown the courage to see the completion of Nash’s project. The current concept of Newport as a ‘City of Bridges’ unwittingly echoes the opportunity lost more than two centuries earlier.
References
1 Jones, B.P. (1957) From Elizabeth I to Victoria: Newport, Monmouthshire, 1550-1850, 102, citing NLW Tredegar (1) 199 and 200.
2 Suggett, R. (1995) John Nash: Architect in Wales, 30-32.
3 Suggett, R. (1995) John Nash: Architect in Wales, 32.
4 http://en.wikipedia.org/wiki/Arch_bridges
5 GRO Q/CB 0001/1
6 GRO Q/CB/0001/2 repeated in Q/CB/0003/12
7 Suggett, R. (1995) John Nash: Architect in Wales, 32.
8 Ruddock, T. (1979) Arch Bridges and Their Builders 1735-1835, 48-51.
http://en.wikipedia.org/wiki/Old_Bridge,_Pontypridd
http://webapps.rhondda-cynon-taff.gov.uk/heritagetrail/big_anthem_fawr/old_bridge_history.htm
http://en.structurae.de/structures/data/index.cfm?ID=s0005448 (for dimensions)
9 Ruddock, T. (1979), 50-51, citing T. M. Smith, ‘Account of Pont-y-tu-Prydd’, Minutes of proceedings of institution of civil engineers, v (1846), 474-7.
10 http://en.wikipedia.org/wiki/Trezzo_sull%27Adda_Bridge
11 http://en.wikipedia.org/wiki/List_of_longest_masonry_arch_bridge_spans
12 Ruddock, T. (1979), Arch Bridges and Their Builders 1735-1835, 136-9.