The residential and commercial redevelopment of the Royal Woolwich Arsenal site, on the south bank of London’s River Thames, features a 19th century clock tower that was in a state of serious disrepair. Combining 3D modelling and knowledge of traditional construction techniques, our structural engineers were able to salvage and reuse more than 85% of the clock tower’s original materials, providing a sensitive and cost-effective solution for its reinstatement.
An assessment of the structure showed that the tower’s condition was too dangerous to allow access, therefore, Ramboll's conservation engineers carried out an inspection using a mobile crane. This revealed severe damage to the front wall and pediment, which had laterally displaced and moved out of plumb. We installed a facade-restraint scaffold before positioning kentledge restraint blocks and hanging trusses.
Once the structure was stabilised, the building’s components were recovered, including the lead cupola and its bells, which weigh three tonnes. During this process, it was realised that the site's main drain connection needed to be installed directly below the kentledge. Steel push-pull props off the reclaimed beams were used to construct flying shores in order to restrain the facade internally.
In assessing the damage to the recovered materials it was found that some of the king-post truss rafters had fractured and some wrought-iron strapping on the joints had failed. Some wood rot was also discovered. The affected materials were replaced with matching timber and wrought iron components. The rebuilt trusses were then tested to 110% of their theoretical full-scale load on a test rig, where strain gauges demonstrated that the deflections were within 0.5mm of our predictions.
The trusses were lifted into position in the rebuilt tower, where cut-outs in the steel strengthening plates allowed us to re-use the original handmade bolts and create traditional timber-to-timber detailing between the new purlins and reinstated king-post trusses.
More about our heritage, conservation and restoration work
Ramboll’s conservation engineers have worked on some of the UK’s most prized historic assets, including the Temperate House at Kew Gardens, Iron Bridge and the Palace of Westminster. Our engineers include people who are Conservation Accredited, IHBC registered and active in recognised national and international heritage bodies such as ICOMOS and the Association for Studies in the Conservation of Historic Buildings. The team take enormous pride in the preservation, restoration and conservation work carried out. To find out more click here.