From the mainland Photo by Ian Warburton
Photo by Eric Jones
The History of the Bridge - It originally looked very different
This was the second bridge to be built across the Menai Strait. Thomas Telford had earlier created the Menai Suspension Bridge 1 mile away.
Prior to the bridges travel to Anglesey from the mainland could be hazardous and while on occasion, when the tides were low, it was possible to walk across them as the water at this time is only 18 inches deep, for much of the time it was difficult due to sand banks, and tricky currents and 4 tides a day in this area.
Ferries crossed the Menai Strait at various places in those times and numerous boats capsized or ran aground, often with loss of life. In 1785 a boat carrying 55 people became stranded on a sandbar in the middle of the southern end of the strait. Attempts to refloat the boat left it swamped. The alarm was raised and rescuers set off from Caernarfon, however, the combination of high winds, nightfall and the fear of also running aground meant that the rescuers could not approach the sandbar. Night fell, the tide rose and of those stranded on the sandbar, one survived, the rest were swept away.
The completion of Telfords suspension bridge made life easer and in particular for those wishing to travel on to Ireland. See Menai Suspension Bridge.
Then in the later part of the 19th century came the rise in rail travel and they wanted to expand the railway through to Anglesey.
The first plan was to build the railway to the suspension bridge, disconnect individual carriages and pull these across the suspension bridge by horse power and then reassemble the train with another engine on the Anglesey side, reversing the process on the way back.
George Stephenson the engine builder was asked to comment on this idea and he had concerns about it, resulting in his son Robert being asked to build a new bridge for the railway. Several prototype experiments were carried out at millwall shipyard, followed by two bridges, the railway bridge at Conwy, next to Telford's Suspension Bridge, and the Britannia Bridge across the Menai Strait. The Conway bridge still stands, virtually unaltered, except reinforcing with extra pillars. It stands next to Conwy Castle, Caernarfonshire and the Conwy Castle Gallery, and is the only remaining Stephenson tubular bridge to still survive. The Conwy Bridge was completed in 1848 allowing confidence to be gained ahead of the opening of the Britannia Bridge. Another bridge designed after these two, but completed before the Britannia Bridge, is the Newcastle High Level Bridge that many think is a later adaptation of the concepts developed here. This has been recently restored and can be walked across.
The design of these two bridges was by Sir William Fairbairn a close friend of Roberts father, who had experience in using cast iron beams and box sections. These were however the first two bridges to be built by creating tubular cast iron sections. He had previously tried to talk Robert out of building a trust cast iron girder bridge across the River Dee in Chester in 1846, and this collapsed in May 1857 under the train going over it, killing 5 people and causing a lot of concern about the safety of other metal rail bridges. Robert Stephenson was criticised at the inquest, although expert witnesses including Brunel and Joseph Locke, to this and the subsequent enquiry refused to criticize him, it did result in a number of bridges being replaced.
The design for the Menai Strait required the Strait to remain accessible to shipping and the bridge to be sufficiently stiff to support the heavy loading associated with trains. To be accessible to shipping meant it had to be high enough that sailing ships could pass under it, without any obstacles and he faced the challenge of building a bridge rigid and strong enough to carry a heavy train of many carriages.
Engraving by John Lucas ((?-1874). Note original bridge in background, part made
Stephenson constructed a bridge with two main spans of 460ft (140m) long rectangular iron tubes, each weighing 1,500 long tons (1,700 short tons), supported by masonry piers, the centre one of which was built on the Britannia Rock and from which it gets its name. Two additional spans of 230ft (70m) length completed the bridge making a 1,511ft (461m) long continuous girder. The trains were to run inside the tubes. Up until then the longest wrought iron span had been only 31ft 6 inches (9.6 m).
The initial idea was that the tubular bridge would be suspended from cables strung through the openings at the tops of the towers. However, after engineering calculations and tests of the finished tubes it was decided that they were strong enough by themselves to carry the trains, but the bridge was still constructed with full sized towers. Robert had also originally proposed that the tube be elliptical in shape, but Fairbairn favoured the rectangular sections. Fairbairn was responsible for the development of the cellular construction of the top part of the tubes and stretching the side walls. A 75ft (23m) span model was created at Fairbairns Millwall shipyard and this was used as the basis for the final design.
Like the Menai Suspension Bridge, the stonework of the Britannia Bridge was constructed of limestone from Penmon, although sandstone from various places was used internally. The tubes were constructed on the banks of the Strait.
They faced a much greater challenge in raising the 1,500 ton finished tubes than Telford had with his much lighter chains. They too would float the tube into position and then lift them, a procedure still used today with many bridges. In this case it didn't go as smoothly with the first tube, as with the Menai Bridge chains, and the giant tube came close to being swept out to sea, however it did finally end up in place. Then, very slowly, using hydraulic pumps, the tube was raised into position. Stonework was built up under the ends of the tube as it was lifted, this was to support it if the lifting equipment failed. This was fortunate because one pump did fail, but the tube only fell nine inches.
Once structurally complete the decoration was added. This included four large limestone lions that guard the entrances to the bridge carved by John Thomas, who had also done stone carving for the Houses of Parliament and Buckingham Palace in London. The lions are almost 4 metres high and sit on plinths of equal height.
The bridge was opened on 5th March 1850.
An old photograph showing the lions Photo by Angus McCullock
Lion Statues at Entrance to Britannia Bridge
The original tubular railway bridge, between Bangor and Anglesey, was designed by Robert Stephenson and opened in 1850. It was destroyed by fire in 1970 and rebuilt to carry both rail and road traffic. The old photograph above shows the Lions guarding the entrance to the old bridge, viewed from the Bangor side before the fire. The image below shows one of lions as seen today, not visible from the A55.
Hidden stone lion not visible from A55. Photo by Ray Jones
The bridge we see today is much different in appearance to the original, and only the towers of the original are now in use, the bridge having been redesigned and redeveloped as a two level bridge following a fire in 1970.
The fire came about not from a train but by a combination of stupidity and an accident. A group of teenagers were looking for bats in the dark tubes using burning paper as a torch. This they dropped and it started a ferocious fire through the whole tubular structure that caused so much damage to the tubes that they were in danger of falling into the Strait. You can see a video clip about the fire, including footage of the flames and an interview with one of the teenagers, on the BBC Wales website.
As assessments were being made as to how to repair the bridge, the local County Surveyor suggested making two bridges out of one. For many years there had been discussions of building a third bridge across the Strait to ease the traffic congestion on the Menai Bridge. A design was produced to allow the Britannia Bridge to be rebuilt as a two level bridge carrying both trains at a lower level and road traffic on top.
Looking from Anglesey Photo by Robin Drayton
A single track railway now runs under the road Photo Eric Jones
Rather than being a tubular bridge the new span is now supported by arches. A single railway track carries the trains to and from Holyhead with a single track instead of two. On top of this is a roadway carrying traffic on the A55 Expressway. The traffic on the bridge is monitored by video cameras that are now connected to the Internet.
Today, the lions that once had pride of place at the entrance to the tubular bridge are still in place but below the the road surface so not seen (see photos above).
More recently there has been talk of a new dual carriageway across the Straits, as the bridge gets very congested at times, one of the proposals was for a third deck on the top. The idea of three narrower lanes instead of two, with one lane switchback in direction from one time of day to another has also been suggested, yet another suggestion would be to widen the road demolishing the top parts of the towers above road level. Another idea is a tunnel, but as the Straits are caused by a geological fault that is active from time to time this is not likely to be practical. In a public consolation 70% of people favoured the idea of a new bridge.
If visiting you can see a section of the original tube preserved and the stone lions. On the Anglesey side the Anglesey Coastal Path goes under the bridge.
A section of the original tube railway bridge, that has been erected
Photo Nigel Williams
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