When the Aberystwyth and Welsh Coast Railway arrived at Fairbourne in 1865, it was only a matter of time before the railway and its benefits should make the relatively short hop over the estuary.
Soon, work to bridge the estuary was started by the engineer Benjamin Piercy and a Darlington contractor, the Cleveland Bridge and Engineering Co Ltd.
The bridge consisted of 113 timber spans and an eight span iron section. Each of the iron columns supporting the structure was around eight feet in diameter and had to sink 120 below sea level to find the rock floor.
Also incorporated into the iron section was a rolling 'cock-and-draw' or 'over-draw' section which could be opened to allow tall sailing ships to continue up the Mawddach estuary.
On 3rd June 1867 the bridge was opened to horse drawn carriages. Locomotive services began in October of the same year.
On 28 July 1900, the 'cock-and-draw' section was opened for the last time. It was replaced by the steel swinging span we see today. Once again, construction was completed by Cleveland Bridge and Engineering Co Ltd.
In 1980, divers discovered that the glamorous sounding Teredo Navalis ship worm had bored into 69 timber piles. The larvae lived in the wood and caused holes several feet in length. The bridge was closed to locomotive traffic on the 13th October whilst a £1.8 million programme of repairs was completed. Eventually, after an absence of over five and a half years Barmouth Bridge was full y reopened to locomotive trains in April 1986.
Today, the bridge is one of the largest surviving timber viaducts in Britain.
It stretches 2292 feet across the Mawddach estuary - that is almost half a mile.
Following the complete cessation of travel by tall ships along the estuary, the swing section is rarely opened. The most recent examples were in March 1984 and April 1987. Both occasions were for test purposes.
