- 15th September 2017
- Posted by: Sophie Bunker
- Category: Projects
On Boxing Day 2015, Storm Eva caused significant damage to the original Copley River Bridge, a twin span masonry arch bridge built in 1831. The extent of the damage was such that it was not possible to repair the existing structure. It was therefore decided to demolish the existing bridge and replace it with a new structure.
The bridge is in a residential area with difficult access, which made the installation of the new structure a challenge. In addition to the site access difficulties, the scheme included significant works within the river.
The scheme included two elements. The first was the demolition of the remains of the existing structure. The second was the construction of the new abutments and the installation of the new steel bridge deck, which carried the footpath and bridleway across the river.
In order to reduce the extent of the work in the river, and to improve the hydraulic capacity at the structure, a single-span deck, 40m long and 3m wide, was designed. The new deck is fixed at one end and free to move at the other to allow for thermal movement.
An extensive ground investigation was carried out to allow the design of piled foundations for the new bridge abutments. The investigation also helped with the design of the temporary works to support the crane, allowing the new bridge deck to be lifted into position.
The original structure carried a number of services including gas and electricity supplies. These were diverted when the original bridge deck was demolished. Service ducts were fixed to the underside of the new bridge deck before it was lifted into position to carry the services.
Where possible, elements of the original structure were incorporated into the proposed permanent works. This reduced the extent of the demolition required and helped secure the river banks in front of each of the abutments.
The single span structure reduced the extent of work required in the river and the upstream flood risk. Although the bridge deck is long, it was possible to lift it in one piece. To reduce the weight of the deck during the lifting operation only part of the timber deck was installed. The remainder of the timber deck was fitted once the structure was in place.