Old Iron Bridge, Merthyr Tydfil
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The Old Iron Bridge of 1800, originally known simply as Merthyr Bridge before 1809, in
Merthyr Tydfil Merthyr Tydfil () is the main town in Merthyr Tydfil County Borough, Wales, administered by Merthyr Tydfil County Borough Council. It is about north of Cardiff. Often called just Merthyr, it is said to be named after Tydfil, daughter of K ...
,
South Wales South Wales ( ) is a Regions of Wales, loosely defined region of Wales bordered by England to the east and mid Wales to the north. Generally considered to include the Historic counties of Wales, historic counties of Glamorgan and Monmouthshire ( ...
, was a
cast-iron Cast iron is a class of iron–carbon alloys with a carbon content of more than 2% and silicon content around 1–3%. Its usefulness derives from its relatively low melting temperature. The alloying elements determine the form in which its car ...
bridge across the
River Taff The River Taff () is a river in Wales. It rises in the Brecon Beacons as two rivers, the Taf Fechan ("little Taff") and the Taf Fawr ("great Taff") before becoming one just north of Merthyr Tydfil. At Cardiff, it empties into the Bristol Chan ...
. Although an important early example of iron bridge-building and well known as a local landmark within living memory, the bridge has largely disappeared from engineering history.


Early iron bridges

The Iron Bridge The Iron Bridge is a cast iron arch bridge that crosses the River Severn in Shropshire, England. Opened in 1781, it was the first major bridge in the world to be made of cast iron. Its success inspired the widespread use of cast iron as a str ...
across the
Severn The River Severn (, ), at long, is the longest river in Great Britain. It is also the river with the most voluminous flow of water by far in all of England and Wales, with an average flow rate of at Apperley, Gloucestershire. It rises in t ...
near
Coalbrookdale Coalbrookdale is a town in the Ironbridge Gorge and the Telford and Wrekin borough of Shropshire, England, containing a settlement of great significance in the history of iron ore smelting. It lies within the civil parish called The Gorge, Shro ...
opened in 1781 and is generally regarded as the world's first cast-iron bridge. It had little immediate influence on bridge design and few other important iron bridges were built as a result. However a flood in 1795 washed away many bridges on the Severn, but the Iron Bridge survived. This survival had more influence on bridge design, as did the completion of
Wearmouth Bridge Wearmouth Bridge is a through arch bridge across the River Wear in Sunderland, England. It is the final bridge over the river before its mouth with the North Sea. Original bridge The original Wearmouth Bridge was designed by Thomas Paine a ...
the following year. Cast iron was now established as a viable material for bridges and a number were produced in the years immediately afterwards.


Earlier bridges in Merthyr

Richard Crawshay Richard Crawshay (1 October 1739 – 27 June 1810) was a London iron merchant and then South Wales ironmaster; he was one of ten known British millionaires in 1799. Early life and marriage Richard Crawshay was born in Normanton in the West ...
's
Cyfarthfa Ironworks The Cyfarthfa Ironworks were major 18th- and 19th-century ironworks in Cyfarthfa, on the north-western edge of Merthyr Tydfil, in South West Wales. The beginning The Cyfarthfa works were begun in 1765 by Anthony Bacon (by then a merchant in ...
was on the West bank of the River Taff, the opposite side from the centre of the developing town. The previous stone bridge had collapsed in the winter of 1798–99. This left the only bridge across the Taff as Jackson's Bridge, which had been built in 1793 by the Dowlais Iron Company. This was an inconvenience to the inhabitants of Merthyr, many of whom now worked for the Cyfartha ironworks, who needed to cross the river to get to the works. Rivalry between the ironmasters was also intense and it was a matter of prestige for Cyfartha workers to not be dependent upon another company's bridge. Small iron bridges already existed at Merthyr, crossing the
Glamorganshire Canal The Glamorganshire Canal () in South Wales, UK, was begun in 1790. It ran along the valley of the River Taff from Merthyr Tydfil to the Bristol Channel at Cardiff. The final section of canal was closed in 1951. History Construction started ...
. This was a far smaller watercourse than the Taff and only needed a simple single-panel bridge. One of these still survives, although now only kept as a monument in a park.


Construction

Richard Crawshay commissioned a new bridge and had
Watkin George Watkin George (1759-1822) was an carpenter, engineer and ironmaster from Trevethin in Monmouthshire (historic), Monmouthshire. He rose from humble beginnings as a carpenter to have a major influence on ironworks at Cyfartha and Pontypool and is re ...
, his principal engineer at Cyfartha and who had also designed the nearby
Pont-y-Cafnau The ; sometimes written ''Pont y Cafnau'' or ''Pontycafnau''), is a long iron truss bridge over the River Taff in Merthyr Tydfil, Wales. The bridge was designed by Watkin George and built in 1793 for his employer, the Cyfarthfa Ironworks, to ...
in 1792, design it. The bridge was built in 1799 and opened at the end of April 1800. The river needed a span of around , which was too much to have been cast in one piece, or then installed, with the equipment of the time. Although structurally an
arch bridge An arch bridge is a bridge with abutments at each end shaped as a curved arch. Arch bridges work by transferring the weight of the bridge and its structural load, loads partially into a horizontal thrust restrained by the abutments at either si ...
, the bridge was cast in three sections, each almost straight. The outer panels were straight, the centre had a rise of in its length. The sides of the bridge were cast as three rectangular panels, including their
balustrade A baluster () is an upright support, often a vertical moulded shaft, square, or lathe-turned form found in stairways, parapets, and other architectural features. In furniture construction it is known as a spindle. Common materials used in its ...
. The ends of the arch were supported on triangular cantilever brackets, cast in two sections. The abutments of the bridge were stone, battered back with sloping faces so that they met the ends of the arch panels perpendicularly. Where the iron castings abutted against each other was packed with oak planks, two or three inches thick and the width of the iron parts. These were bolted through and clamped. The intention was to give the iron structure some degree of flexibility, as otherwise it would be too brittle. However the short life of the timber gave trouble twenty years later and the bridge required extensive repairs. The balustrade of the bridge did not form a structural part of it, although it was cast in situ with the main panels. There were three perpendicular uprights to each panel, with strips forming a pair of intertwined waves between them, giving an 'X' shape in each of the four spaces. These were cast integrally, but had the appearance of
wrought ironwork Wrought iron is an iron alloy with a very low carbon content (less than 0.05%) in contrast to that of cast iron (2.1% to 4.5%), or 0.25 for low carbon "mild" steel. Wrought iron is manufactured by heating and melting high carbon cast iron in an ...
. Three horizontal strips of wrought iron were riveted to the back, to make the gaps in the balustrade smaller, and these appear to have been added later. Its
parapet A parapet is a barrier that is an upward extension of a wall at the edge of a roof, terrace, balcony, walkway or other structure. The word comes ultimately from the Italian ''parapetto'' (''parare'' 'to cover/defend' and ''petto'' 'chest/brea ...
also included 'heart-shaped' motifs at the centre of the bridge, distinctive to the work of Watkin George. The deck of the bridge was formed of cast iron crossbeams. These were an inverted T in section, six inches on each arm and " in section thickness. With a length of twelve feet, they gave a useful carriageway wide. These crossbeams may have been added in the extensive 1817 repairs. The surface of the bridge was formed of stone
sett A sett or set is a badger's den. It usually consists of a network of tunnels and numerous entrances. The largest setts are spacious enough to accommodate 15 or more animals with up to of tunnels and as many as 40 openings. Such elaborate setts ...
s or cobbles, but these gave a poor surface for walking as they were uneven between the gaps and slippery in rain. In later years the surface was dressed smooth with a layer of the abundant ironworks slag. The iron sections are thought to have been
cast Cast may refer to: Music * Cast (band), an English alternative rock band * Cast (Mexican band), a progressive Mexican rock band * The Cast, a Scottish musical duo: Mairi Campbell and Dave Francis * ''Cast'', a 2012 album by Trespassers William ...
in open-backed single-sided sand moulds, as one surface shows evidence of surface bubbles.


Repairs

A series of inspections and repairs were made to the bridge, at two year intervals, from 1801 to 1809. Most of these were to the stonework of the bridge abutments or the stone retaining walls of the riverbank, particularly for improvements to reduce the effects of flooding. The 1809 report on its condition was the first time the name 'Iron Bridge' was recorded.


1817 repairs

In 1817, major repairs were made to the ironwork of the bridge itself. William Williams, Watkin George's successor as chief engineer of the ironworks, made a report on its condition and recommended that an iron decking of flat plates should be applied over the existing structure, then a pavement of stone or iron treads be applied over that. The work carried out is not known, but the costs of it exceeded those that would be expected for a mere re-surfacing. The total cost £354 1s 10d, with £196 11s 6d paid for castings and £147 0s 2d for labour. Williams was paid 10 
guinea Guinea, officially the Republic of Guinea, is a coastal country in West Africa. It borders the Atlantic Ocean to the west, Guinea-Bissau to the northwest, Senegal to the north, Mali to the northeast, Côte d'Ivoire to the southeast, and Sier ...
s for his involvement. It has been suggested that the cross girders directly beneath the surface of the bridge had been installed during the 1817 repairs, their cost explaining the large sum of paid for castings. 1816 and 1817 were boom years for the building of iron bridges in Britain and many surviving bridges date from this period.
Waterloo Waterloo most commonly refers to: * Battle of Waterloo, 1815 battle where Napoleon's French army was defeated by Anglo-allied and Prussian forces * Waterloo, Belgium Waterloo may also refer to: Other places Australia * Waterloo, New South Wale ...
had ended land warfare in Europe but this led to widespread economic and civil disruption. Despite this, ironmasters sought markets for their increasing capacity and to recover the lost markets for military ordnance. Roadbuilding and bridge projects could stimulate a local economy and trade, whilst also providing employment to the demobilised soldiers.


1852 repairs

The 1852 report was carried out Henry Wren, Superintendent of the local Board of Health. He found that the bridge was significantly decayed, particularly the timber packing between the castings. He went so far as to suggest that the bridge was both unsafe in its current state and that it was beyond economic repair, largely due to the need to dismantle it almost completely. He suggested instead that the first consideration be given to a replacement, and that this replacement should be in the location of the later Ynysgau Bridge. Such a bridge could be wider, better suited to vehicles, and would be aligned with the two main roads on each side of the river. However a committee of three was tasked with deciding on what to do with the bridge and they chose instead to repair it. The cost was £66 12s 6d, more than half of which was for timberwork.


1860 report

By 1860, after a long delay, the Board of Health decided to seriously consider replacement and began with a traffic survey of the current bridge. For a week in June–July, daily traffic from 8am to 8pm was counted: The recommendation was to construct a new bridge and an estimate of £1,700 was given as the cost of this.


Replacement

A replacement bridge was long overdue; apart from the concerns over its structure, its narrowness and the amount of traffic using it led to accidents. In 1872, a young girl lost both her legs after being run down by a cart.


Ynsygau Bridge

In March 1880, a new and larger bridge, the Ynysgau Bridge, also called the New Iron Bridge, was eventually opened next to the old bridge. The Ynysgau Chapel had been built in 1749 on the East bank of the Taff, adjacent to where the first bridge would be built. The Old Bridge has sometimes been referred to as the Ynysgau Bridge, but this is a modern anachronism, after both had been demolished, and the name belongs to the later bridge. The original bridge crossed the river perpendicularly, so as to be the shortest span. The new bridge was on a skew, giving a straighter alignment between Penry Street on the West and into Victoria Street. This required a longer bridge, and it was also widened to be more easily capable of carrying vehicle traffic. This bridge was made of
wrought iron Wrought iron is an iron alloy with a very low carbon content (less than 0.05%) in contrast to that of cast iron (2.1% to 4.5%), or 0.25 for low carbon "mild" steel. Wrought iron is manufactured by heating and melting high carbon cast iron in an ...
as a
lattice truss A lattice truss bridge is a form of truss bridge that uses many small, closely spaced diagonal elements forming a lattice. The design was patented in 1820 by architect Ithiel Town. Originally a means of erecting a substantial bridge from mere p ...
structure. This allowed it to have a flat and horizontal deck all the way across.


Removal

The bridge remained in use until WWII, although as just a footbridge with bollards to prevent vehicles, after which the ends were fenced off, pending its demolition. However, once again, the bridge's demise was postponed and it remained in use through the 1950s. In the late 1950s, concern at protecting the town from the river's near annual floods, and the increasing number of motor vehicles, led to a widespread scheme to widen the river and canalise it between robust banks. This included a new, wider, bridge in 1958, just north of the iron bridges, a weir to control flow, and demolition of several buildings adjoining the river. By September 1963, the bridge was still standing but the surface material had been removed, exposing the cross-girders. The complete bridge had gone by the end of November. By January 1967, all trace of both iron bridges had been removed and the Taff had new, wider concrete banks. The Ynsgau Chapel was demolished a few months later.


Storage

Components are still stored in the grounds of
Cyfarthfa Castle Cyfarthfa Castle (; ) is a castellated mansion that was the home of the Crawshay family, ironmasters of Cyfarthfa Ironworks in Park, Merthyr Tydfil, Wales. The house commanded a view of the valley and the works, which ‘at night, offer a tru ...
by Merthyr Tydfil CBC, for possible re-erection. Little is known of them and there are no plans to re-erect them. They are not on general display and many heritage groups are even unaware of their existence. They were photographed there in 2015 by Christopher Tipping. Some damage is evident, either in storage or during demolition.


See also

*


References

{{Coord, 51.7463, -3.3820, region:GB, display=title Cast-iron arch bridges Bridges over the River Taff Bridges in Merthyr Tydfil History of Merthyr Tydfil