The Menai Suspension Bridge (Welsh: Pont Grog y Borth) 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 building. 

Construction

Before the bridge was completed in 1826, the island had no fixed connection to the mainland and all movements to and from Anglesey were by ferry across the fast flowing and dangerous waters of the Menai Strait. 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, a dangerous practice which often resulted in the loss of valuable animals.  With Holyhead as the closest point to, and thus one of the principal ports for ferries to Dublin, Engineer Thomas Telford was engaged to complete a survey of the route from London to Holyhead, and he proposed that a bridge should be built 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.

Because of the high banks and fast flowing waters of the Strait, it would have been difficult to build piers on the shifting sands of the sea-bed and, even if it could be done, they would have obstructed the navigation. Also, the bridge would have to be high enough to allow the passage of the tall ships of the day. In view of this, Telford proposed that a suspension bridge should be built and his recommendation was accepted by Parliament.

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 176-metre (577 ft) span.  To avoid rusting between manufacture and use, the iron was soaked in linseed oil and later painted.  The chains each measured 522.3 metres (1,714 ft) and weighed 121 tons. Their suspending power was calculated at 2,016 tons. The bridge was opened to much fanfare on 30 January 1826.

Later history

The roadway was only 24 ft 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.^[5] Over the years, the 4.5 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.

Sumber :

https://en.wikipedia.org/wiki/Menai_Suspension_Bridge