BRIDGES Ӏ SECTOR SNAPSHOT
CRANE PONTOON KEY TO CANAL WORK
In the UK the Droitwich Canals flow through the spa town of the same name. They are thickly lined with trees and hedges and provide a green haven for local walkers. The canals have also become a thriving cruising ring for boaters looking to navigate the picturesque Mid-Worcestershire Ring. Two commonly used wooden
footbridges span the waterway at King George Playing Fields and Little Hill Court; each is 18 metres long. In January 2024, it was decided both bridges would be removed and replaced; contractor Griffiths was chosen to carry out the project. Each bridge weighed seven tonnes and was hard to dismantle conventionally. In addition, there was no land access for the large lifting equipment needed. Thomas Roberts, site manager at Griffiths, said: “From a civil engineering perspective, dismantling and replacing bridges is undoubtedly difficult and requires a lot of planning. When the bridge is over a body of water, the difficulty factor multiplies further: the bridges needed to be stripped down, replaced and lifted into place on the canal itself, so we knew specialist equipment and knowledge would be needed to carry this out.” Faced with this challenge Griffiths
engaged the services of marine engineering specialist The Rothen Group. The group was able to provide a 26ft (8 metre) crane pontoon, allowing works to be carried out on the water by construction machinery. Capable of lifting two tonnes at 12m,
the platform could also be adapted to narrow and wide beam waterways, suiting the awkward-to-access circumstances of each bridge’s location. Crucially, the pontoon has jack legs, creating a stable working platform while the projects were carried out.
“Dismantling the old bridges proved
difficult from a health-and-safety perspective, as it quickly became apparent that the old wood had rotted,” said Group founder Ian Rothen. “We were able to meet this challenge using scaffold towers mounted on the pontoon and extra harnesses off the crane to carry out the first stage of the works.” All disassembled and discarded materials from the bridges were loaded onto a 70-foot historic carrying boat to be disposed of off-site. This hopper was then crucial to the next part of the project, carrying the new bridges to where they would be lifted and fixed in position via the pontoon-based crane. New ramps were also put in place as part of these works, followed by the installation of handrails – also from the pontoon. In total, the project took 11 weeks to complete, with the bridge installations themselves taking just two days each despite their scale. “The sheer size of these bridges made them some of the biggest we had ever erected,” said Ian Rothen. “Our largest boat is 21 metres, so considering the bridges were 18 metres long, the whole project was very tight. However, we drew on our years of experience to ensure the complex project was completed without a hitch.”
28 CRANES TODAY
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