The Britannia Bridge tubes crossed the strait in four spans, on three masonry support towers between masonry abutments. One tower sits on each bank with the tallest, The towers and abutments are rectangular in section, fashioned in 'Egyptian Pylon' style from Anglesey limestone and Runcorn sandstone. Each partly hollow tower has two square holes per side near the top, in all eight on each tower. Stone lintels 6.
Each of the tubes consisted of four spans connected end to end within the towers. The two central bays had clear spans of m each, with a 70m clear span at either side. To allow for expansion and contraction, Stephenson had the tubes fixed in the central tower but mounted them on rollerbeds in the side towers and abutments. The side tubes were built first, in situ, on wooden platforms.
Meanwhile, the two great central tube sections, weighing 1, tonnes apiece, were built on the Caernarfon shore and floated, one at a time, into position.
They were then jacked into place using hydraulic pumps, with supports being built underneath at every few inches. The Conwy bridge tubes had been successfully manoeuvred into position by the time the first Menai tube was ready.
Nonetheless, Stephenson lost many nights' sleep over his method of construction. The two men stood together to watch the first huge tube float out on its pontoons on 20th June Once in place, the separate lengths of tube were joined to form parallel prestressed continuous structures, each The prestressing increased the loadbearing capacity and reduced deflection. The tubes were 4. This would result in being able to span a greater distance and carry the force of heavy loads crossing the bridge.
The construction of the Britannia Bridge was started in and completed four years later in March The tubes were constructed onshore on the banks on the Menai Strait before being floated out into place and hydraulically pumped into position. The Britannia Bridge remained in use and was claimed to be the most easily maintained railway bridge in Britain, until when the bridge caught fire. A group of local youths exploring the tubes of the bridge accidentally dropped their burning torch and the bridge caught fire.
Some of the tubes were visibly sagging after the fire and the bridge was classed unsafe. It was not until four years later that normal rail services across to Anglesey were resumed. You can see video clips about the fire, including footage of the flames and an interview with one of the teenagers, on the BBC web site and Youtube or a longer version on YouTube , and the 2d During reconstruction after the fire the bridge changed dramatically.
The tubes were no longer used and the deck was supported by arches spanning between the towers. The original towers remain but have also been altered to suit the new design of the bridge. In , ten years after the fire a road deck opened above the railway on the bridge, which carries the A55 across to Anglesey.
A Youtube video tells the story of the reconstruction, with lots of archival footage. The Conway Bridge is still in its original tubular form and is still in use over years later.
A section of the tubes of the Britannia Bridge can be seen on the Bangor side of the Menai Strait, close to the bridge itself. Is a magnificent prototype box-girder design by William Fairbairn and Robert Stephenson. Originally built to carry rail traffic, this bridge was converted to a double-decked structure following a catastrophic fire in It now carries both rail and road traffic.
A short walk from Menai Bridge town centre brings the visitor to the base of the Menai Suspension Bridge, from where the true scale of this remarkable structure is best appreciated. The Belgium Promenade built by Flemish refugees from the Great War between leads south west from here shortly reaching a causeway that links Church island and the ancient Church of St Tysilio to the shore.
A short walk around the church cemetery affords wonderful views of the Menai Strait, both bridges and Ynys Gorad Goch island, whose residents once made a living from the fish caught at the traps built there.
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