The scope of works involved decommissioning 40% of the bridge from the base, excavating and drilling the structure to remove a section of the bridge, in order to create space for a new culvert. Prior to the partial demolition of the bridge, the existing three-span bridge was filled and the vast variety of services and utilities within the bridge had to be diverted, including a large volume of EHV (Electrical High Voltage) circuits and telecom utilities belonging to multinational corporations such as Vodafone and BT.
FM Conway were also commissioned to divert a Thames Water main, a one-metre diameter pipe that ran north-to-south on the east side of Lisson Grove bridge, which supplied water to over 250,000 residents of London each day. As previously mentioned, this was achieved by the construction of a reinforced concrete culvert structure located between the decommissioned bridge and proposed residential building.
Ismet Sakajani, Contracts Manager at FM Conway, explains:
“The culvert had to be extended on either end of the bridge using a piled wall structure, comprising 20-22 metres deep and 1 metre diametre piles, as well as ground anchors to maximise the strength of the ground and retain the highway embankment."