Engineering ingenuity: Floating tower crane at 2 Finsbury Avenue

Creative solution to a tower crane conundrum

Creative thinking and engineering expertise have come to life in the form of a striking tower crane arrangement at our 2 Finsbury Avenue site on the Broadgate Campus in the City of London.

Rather than being anchored to the ground, the tower crane located at the North East corner of the development cantilevers out off the East Tower core, supported by an impressive steel grillage.

This ‘floating crane’ is an ingenious solution to a complex construction challenge.

Our team needed a tower crane in this corner of the site to give them the hook coverage they required to service this flagship twin tower project for British Land.

With insufficient space between our site and the neighbouring building to the East to fit a tower crane whilst still maintaining emergency services access, the team looked at positioning a standard tower crane where the raked crane was eventually to be located.

But with the ground congested with buried services, they were presented with the tricky conundrum of erecting a tower crane in a seemingly impossible location.

Step forward our clever colleagues from McAlpine Lifting Solutions, who, after careful consideration, came up with the solution of keeping the crane where the team need it but moving the base out of the ground. For this they envisaged a supporting steel grillage cantilevered off the core of the East tower and cranked to suit the profile of the new building’s structure and façade.

Having developed the original concept, our McAlpine Lifting Solutions team passed the baton to McAlpine Design Group (MDG), who carried out the detailed design including design optimisation and completed all the necessary structural analysis and calculations to ensure the solution performed as required.

The supporting steel grillage and tower crane were erected over nine days in August using a 350t mobile crane.

The tower crane currently stands some 40m tall but will eventually climb to 170m to match the height of the 37-storey East tower.

That’s a lot of ladder for our tower crane drivers to climb, so we are installing a lift to take them up at least part of the way. The lift will start around 10m above the crane feet and eventually travel up 80m of mast.

The tower crane is a great example of engineering excellence delivered in–house and the first of many we will no doubt see on this project.