Topbond completed this scheme as part of the framework agreement with Transport for Buckinghamshire. Berry Hill footbridge was constructed to carry a footpath across a newly constructed flood relief channel which opened in 2002. The project objectives were to safely remove the central span of Berry Hill footbridge which had a span of 36.7m and estimated weight of around 35t. A lower chord had failed, and the bridge was closed to the public due to its dangerous condition. The bridge was monitored on a regular basis by Topbond and it was found that the structure was becoming progressively more unstable and as such needed to be removed as soon as possible to avoid the structure collapsing into the watercourse.
The flood relief channel at the location of the bridge is over 60m wide. With no vehicular access, it would require significant temporary works and reinstatement after removal of the bridge to allow an 800t crane to access the site. There is also a medium pressure gas main which is located in the area that the crane would need be set up if the bridge were to be lifted out which would have required significant protection. Difficult access for the crane, combined with the poor condition of the bridge Topbond decided to look at alternative systems for removing the bridge.
Topbond collaborated with the client and Environment Agency, as the bridge was located over a flood relief channel there was an urgency to ensure works were completed before winter arrived thus increasing the likelihood of the flood relief channel becoming operational. It was established that a system was required that would allow for work to be safely suspended should high flow levels be predicted.
Topbond decided that the most appropriate method would be to use a pontoon system onto which bespoke jacking towers and frame were installed. This design allowed the bridge to be supported over the majority of its span reducing the likelihood of the bridge failing during the jacking process. The temporary works system was fabricated within the Topbond Group and everything installed into the flood relief channel using a mobile crane from a bridge located approximately 200m upstream. When the bridge was jacked up it was then transported up the flood relief channel and cut into four sections before being lifted onto road transport & recycled off site.