The Menai Suspension Bridge
Telford's Menai Bridge was the world's longest suspension span in 1826, and its deck was once hung so loosely that wind made it ripple like a ribbon.
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Quick Facts
- Location
- Across the Menai Strait, linking Anglesey with the Gwynedd mainland at Menai Bridge
- Opened
- 30 January 1826
- Designer
- Thomas Telford
- Main span
- 176 metres (579 feet) between the towers
- Clearance
- About 30 metres (100 feet) above high water, so tall ships could pass beneath
- Support
- Eight steel chains in two groups of four, installed in 1938–1940 to replace the original 16 wrought-iron chains, carried over two stone towers
- Approach arches
- Seven stone arches: four on the Anglesey side and three on the mainland
- Heritage status
- Grade I listed
The bridge that made the Irish mail run on time
Before 1826, getting to Anglesey meant a ferry across a strait with fierce, unpredictable tides. Crossing could be slow, scary and sometimes fatal. Yet Anglesey mattered enormously, because Holyhead was the port for Dublin. After the Act of Union with Ireland in 1801, MPs had to travel between London and Dublin, and the mail had to keep moving. The road across north Wales was a mess. The government hired Thomas Telford to build a proper highway, now known as the A5, and the Menai Strait was the biggest obstacle on it. His answer was a bridge with a span of 176 metres, longer than any suspension bridge then built. The Admiralty insisted on one condition: the roadway had to be high enough for sailing ships to pass beneath at full rig. That requirement set the height of the whole design.
Chains, stone and a lot of boiled linseed oil
Telford chose suspension over arches or iron girders because a span that long couldn't be supported from the water. The strait was too deep and too busy. The bridge originally hung from 16 wrought-iron chains, arranged in four groups of four. Each was made of flat iron links bolted together, and they passed over two stone towers. Every link was tested before use. Telford had them dipped in hot linseed oil to protect against rust, a precaution that helped them last well beyond expectations. The towers and approach arches are built from limestone quarried at Penmon, on the eastern tip of Anglesey, and shipped across the strait. Seven stone arches carry the approaches, four on the Anglesey side and three on the mainland, and they are part of why the bridge looks so graceful from either shore. Work began in 1819. The first chain was raised into place in 1825, and the whole structure was ready in less than seven years.
Opening day, and the first crossing
The bridge opened on 30 January 1826, in the small hours. The first vehicle across was the Royal Mail coach from London to Holyhead. The journey time shortened dramatically, and the crossing no longer depended on the tide. For the first time, a coach could drive to Anglesey without anyone getting wet. The Anglesey end was already a ferry settlement, Porthaethwy, before the bridge existed. It expanded during and after construction, and became known in English as Menai Bridge.
The deck that wouldn't sit still
Telford's masterpiece had a flaw. Its deck was light and flexible, and in strong winds it moved. In a gale in February 1826, just days after opening, the roadway rippled so badly that it was a concern. A storm in 1839 was worse, with the deck heaving and swaying so alarmingly that part of it was damaged. The repair work after 1839 added stiffening to the roadway. The bridge was strengthened again over the following decades, and its wooden deck was replaced with a steel one in 1893. A major reconstruction came in 1938–1940, when the 16 original wrought-iron chains were replaced with eight steel ones, in two groups of four. The towers and arches are still Telford's. The lesson about wind and flexible decks came to matter more than anyone realised in the age of suspension bridges.
Next to Stephenson's tubes: a famous neighbour
A short distance to the south-west stands the Britannia Bridge, built by Robert Stephenson for the railway and opened in 1850. It was designed around huge iron tubes through which trains travelled. A fire in 1970 destroyed the tubes, and the bridge was rebuilt with an arch design and a road deck added above the railway. By the 20th century Telford's bridge could no longer carry all the traffic heading to Holyhead, so the Britannia took on much of the load. Telford's bridge remains open to road traffic, and it is Grade I listed. For the best view, walk down to the Belgian Promenade or the shore path at Menai Bridge. From there you can see the lines of the stone arches and the curve of the chains, with the dark waters of the strait racing underneath. Look up at the towers and notice how the limestone changes colour in different light.
Notable people
- Thomas Telford
- Robert Stephenson
- William Provis
Test yourself
Play the UK quizMore to see nearby
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