Menai Suspension Bridge

The Menai Suspension Bridge () is a suspension bridge to carry road traffic between the island of Anglesey and the mainland of Wales. The bridge was designed by Thomas Telford and completed in 1826 and is a Grade I listed structure.
Background.
The Menai Strait was created by glacial erosion along a line of weakness associated with the Menai Strait Fault System. During a series of Pleistocene glaciations (that lasted from about 2,580,000 to 11,700 years ago) a succession of ice-sheets moved from northeast to southwest across Anglesey and neighbouring Arfon scouring the underlying rock creating a series of linear bedrock hollows. The deepest of these channels eventually became flooded by the sea as the ice sheets receded forming the Menai Strait.
As Anglesey has been an island throughout recorded human history, the only way to reach it was by crossing the strait. However, this has always been a dangerous endeavour because there are four daily tides which flow in two directions creating strong currents and whirlpools that can sink small vessels. Despite the dangers, ferries operated all along the Menai Strait carrying passengers and goods between the island and the mainland. In 1785, a boat carrying 55 people ran aground at the southern end of the Menai Strait in a strong gale and began to sink. Before a rescue boat from Caernarfon could reach the stricken vessel it sank, only one person survived. Likewise the main source of income on Anglesey was from the sale of cattle, and to move them to the markets of the mainland, including London, they had to be driven into the water and encouraged to swim across the Strait, which often resulted in the loss of valuable animals.
In 1800 Ireland joined Great Britain in the Act of Union. This led rapidly to an increase in people travelling between London and Holyhead en route to Dublin. In 1815, the British Parliament enacted an Act to build the Holyhead Road with responsibility for the project given to civil engineer Thomas Telford. Despite some difficult geographical obstacles to overcome (e.g. Snowdonia and the Menai Strait), the route was chosen because Holyhead was the principal port for ferries to Dublin as it was the closest point to Ireland. After Telford had completed a survey of the route from London to Holyhead, he proposed that the best option was to build a bridge over the Menai Strait from a point near Bangor on the mainland to the village of Porthaethwy (which is now also known as Menai Bridge) on Anglesey.
The site for the bridge was chosen because it had tall banks that would be high enough to allow the passage of sailing ships to pass underneath. Telford proposed that a suspension bridge would be the best option because it would have a span wide enough to cross the fast flowing waters of the Strait at this point. His recommendation was accepted by Parliament.
Construction.
Construction of the bridge, to Telford's design, began in 1819 with the towers on either side of the strait. These were constructed from Penmon limestone and were hollow with internal cross-walls. Then came the sixteen huge chain cables, each made of 935 iron bars, that support the span. To avoid rusting between manufacture and use, the iron was soaked in linseed oil and later painted. The chains each measured and weighed . Their suspending power was calculated at . The bridge was opened to much fanfare on 30 January 1826.
Later history.
The roadway was only wide and, without stiffening trusses, soon proved highly unstable in the wind. The deck of the Menai Bridge was strengthened in 1840 by W. A. Provis and, in 1893, the entire wooden surface was replaced with a steel deck designed by Sir Benjamin Baker. Over the years, the -ton weight limit proved problematic for the increasing freight industry and in 1938 the original wrought iron chains were replaced with steel ones without the need to close the bridge. In 1999 the bridge was closed for around a month to resurface the road and strengthen the structure, requiring all traffic to cross via the nearby Britannia Bridge.
On 28 February 2005 the bridge was promoted to UNESCO as a candidate World Heritage Site. On the same day one carriageway of the bridge was closed for six months restricting traffic to a single carriageway so that traffic travelled to the mainland in the morning and to Anglesey in the afternoon. The bridge was re-opened to traffic in both directions on 11 December 2005 after its first major re-painting in 65 years.
Surroundings.
The Anglesey Coastal Path passes below the bridge. The bridge has a memorial to the Aberfan disaster victims on the Anglesey side.
Cultural references.
The nearest settlement is the town of Menai Bridge.
A representation of the Menai Bridge inside a border of railings and stanchions is featured on the reverse of British one-pound coins minted in 2005. The coin was designed by British designer and engraver, Edwina Ellis.
Operation Menai Bridge is the official funeral plan in the event of the death of Charles, Prince of Wales.