Musselburgh New Bridge is a fine example of a Rennie bridge and one of his Scottish bridges that were influential in his later designs for Waterloo, Southwark and London bridges. The bridge is a 5-span masonry arch bridge built of grey-yellow sandstone, spanning the River Esk in the East Lothian town, near Edinburgh. The Musselburgh New Bridge was built as part of the Edinburgh-Berwick-London post road that later became the main A1 trunk road between Edinburgh and London, and it was an important transport link before railways became dominant.
Rennie’s design drawings are dated 1803, and the bridge was built between 1806 and 1808. It has Rennie’s characteristic low-rise elliptical arches varying from 11.3m to 14m span, with a total span of 73m, and has a low soffit height of just over 4m above water level. The 2m thick bridge piers and semi-circular cutwaters were originally supported on timber piles, with the two central piers standing in the river and the other four on the wide river banks. The design gives a near-level road surface in contrast to many contemporary bridges built in Rennie’s time and before. An example is the Old Bridge, a few hundred metres upstream, which has a significant level difference between the deck and the banks, connected by steep steps.
The comments of a local farmer making the crossing of the Rennie’s new bridge at Musselburgh, put its near-level deck in context. “Brig,” answered the man in response to the query of a Magistrate in the company of Rennie, “it’s nae brig ava; ye neither ken whan ye’re on’t, nor whan ye’re aff’t.”
Over time, road traffic began to compete with rail, and the new tram route over the bridge in the 20th century added to both to the bridge loading and vehicle congestion. In 1923, Musselburgh Corporation decided to have the bridge repaired and widened, to maintain the now-vital trunk route. The consulting engineers were Blyth & Blyth of Edinburgh.
Although the use of reinforced concrete was common by this time it was decided to retain the original stone arches as far as possible and most of the original stonework was reused. The piers were founded on concrete piles, the top of which were 3m below the river bed, and during excavation, the original timber piles were found to be in good condition. The original width of the bridge was 10.5m between the parapets, and this was widened to 16.2m, with all of the extension being on the eastern, seaward side. The bridge carries less traffic since the new A1 bypassed the town, but it is still in daily use as the main route through Musselburgh, some 220 years after it was originally built.
The bridge is a ‘B’ listed structure, most likely because of the widening works, as Rennie’s contemporary Kelso Bridge and Telford’s later Dean Bridge are ‘A’ listed, but basically unaltered.
A metal plaque on the north parapet of the bridge notes ‘This bridge was built by John Rennie, Engineer, 1806*. Repaired and widened 1924-5. Alexander Mitchell, Provost, Blyth & Blyth, Engineers, John Angus and Sons, Contractors’.
*The bridge was actually completed in 1808.