Menai Suspension Bridge
Completed on 30 January 1826, the Menai Bridge was a triumph of civil engineering – the biggest suspension bridge in the world at the time. Sixteen huge chains held up 579 feet of deck, giving 100 feet of clearance for tall sailing ships navigating the Menai Strait. The Menai Bridge not only made Thomas Telford’s reputation as a civil engineering superhero, it also dramatically reduced the time and dangers involved on the journey from Ireland via Holyhead to London. Along with Telford’s other improvements to the London to Holyhead Road, the journey time was reduced from 36 hours to 27 hours. The Bridge you see today was modernized and strengthened between 1939 and 1940.
Britannia Rail Bridge
Robert Stephenson chose to build his magnificent Egyptian themed, tubular rail bridge at the second narrowest point on the Menai Strait. Begun in 1846, the bridge was opened on 5 March 1850. The design required the bridge to be sufficiently stiff to support the heavy loading associated with trains, so Stephenson constructed a bridge with two main spans of 140-m 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. Two additional spans of 70-m length completed the bridge making a 461-m long continuous girder. The trains ran inside the tubes. For its time, it was a bridge of "magnitude and singular novelty", far surpassing in length contemporary cast beam or plate girder iron bridges. One aspect of its method of construction was also novel; the box sections were assembled on-shore, then floated out into position before being gradually lifted into place using powerful jacks.
The design of the bridge greatly influenced engineering throughout the world. A disasterous fire in 1970 damaged the structural integrity of the tubes and the current bridge is a two tier steel arch truss design carrying not only the railway from London to Holyhead but also a major European roadway, linking Continental Europe to Ireland.
The full history of the bridges and several artefacts can be seen at the Menai Heritage museum.