Multiplex asked its engineers to dream up the innovative solution for the 22 Bishopsgate tower which is so close to the pavement that there was no room for the crane in the busy street.
Engineers from Robert Bird Group came up with an ingenious design that inverts the mast at the base, tilting it back into the site.
A four-sided inverted steel pyramid stands on a pile cap and carries a standard tower crane section at a 20° angle.
A top steelwork fabrication braces the skewed structure back to the structural frame.
Tower crane sections can now be added vertically, outside the line of the building envelope, minimising disruption to the façade.
For the permanent works Severfield are the steel frame specialist contractors, who are site welding to connections embedded in the concrete cores by Carey.