The Grade I structure, which was formed in 1826, is a crucial road link between mainland Wales and the Isle of Anglesey and is the second oldest suspension bridge in the world still carrying vehicle traffic.
Spencer Bridge Engineering, in collaboration with UK Highways A55 Ltd, completed the works which included replacing and painting 168 of the 208 wire rope hangers on the bridge, restoring the full structural integrity of the structure and removing the critical risk to public safety which forced it to close in October 2022.
Project Manager Tom Inglis said: "The project posed a number of significant challenges, including working in a harsh environment with strong winds and wet weather, but we have a large and diverse skillset which enables us to draw on past experiences to develop solutions.
"We have decades of experience working on a range of complex bridge and infrastructure projects, and with a very collaborative attitude, allowing us to utilise expertise from right across the team to deliver the most efficient and effective results.
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"One of the factors which made this project so successful was the close relationships we have developed over a number of years with the client, UK Highways A55 Limited, and our suppliers. Those relationships were especially important to deliver this challenging project on time."
Teams from Spencer have been carrying out a series of works over the past four years to revitalise the crossing ahead of its 200th anniversary year.
After completing earlier projects, including the replacement of footpath panels and the installation of emergency fail-safes on the 417m-long bridge, Spencer Bridge Engineering's expert team began the hanger replacement project in Autumn 2023 and recently completed the final hanger installation.
To respect the heritage and historic features of the bridge, the team worked closely with suppliers throughout a rigorous period of development and testing to design the specially fabricated hangers and sockets.
The hangers, which range in length from less than 1m to over 14m, were fabricated to a stringent specification, with an incredibly narrow length tolerance, by specialist Swiss steel manufacturer, Fatzer AG.
Works were carried out to replace the historic hangers, which were installed when the bridge was reconstructed in 1938.
To undertake the works, Spencer's highly experienced bridges team also designed bespoke equipment, including a de-tensioning rig and pin pusher to safely remove the existing hangers while protecting the surrounding bridge structure.
The completion of the hanger replacement programme to schedule marks a significant engineering achievement for the team given the complexity of the programme and the speed with which it needed to be designed, procurement and supply chain challenges, and adverse weather conditions over the works period.
A spokesperson for UK Highways A55 Ltd said: "The Menai Suspension Bridge is an icon of civil engineering and a beloved part of local and national heritage.
"The completion of the hanger replacement programme to schedule is a significant achievement and we are proud to have completed these works thanks to the outstanding leadership of Spencer Bridge Engineering.
"We hope the pause in works over the winter will benefit local residents and businesses with less disruption and improved access during the holiday period."
