Bringing down a giant

Having already established a robust methodology to climb down the tower crane, the team saw an opportunity to gain time and reduce programme risk by changing its approach and using a giant crawler crane supplied by Mammoet.

With a boom reaching almost 200 metres into the London skyline, it is the sort of crane you’d normally expect to see lifting wind turbines or working on large industrial projects.

It’s a methodology rarely seen in such a tight city-centre environment and one that required extensive planning, analysis and collaboration.

Above ground, we had to navigate neighbouring buildings, narrow streets and some of the busiest transport routes in the capital. The crawler crane's location had to be carefully coordinated with existing infrastructure while bollards and other street furniture were temporarily removed to create the necessary working area.

Below ground, the situation was equally complex. The presence of a shallow Victorian gas main beneath part of the crane's operating footprint meant detailed geotechnical assessments and load modelling were required to understand how forces would be transmitted through the ground. The team designed a precisely engineered sand bed and load-spreading arrangement to ensure the crane could operate safely without exceeding allowable limits.

They also used purpose-designed, fabricated steel trusses to support the space between the tarmac and the crane’s boom, negating the need to transport and store shipping containers normally used for such purposes – an impractical solution for a constrained city centre site.

With safety at the forefront of the operation, and wind conditions dictating every move, progress was incremental. Continuous weather analysis ensured we were ready to mobilise and make the most of every available window before strengthening winds forced work to stop again.

One of the most challenging stages involved lowering the crane's 50-metre jib between neighbouring buildings with minimal clearance. Detailed tagline procedures were developed and reviewed, while bespoke lifting arrangements kept heavy equipment away from the façade. Where possible, components were combined into single lifts, reducing time spent operating in the most constrained areas.

An operation on this scale required impeccable coordination between the project team, our in-house lifting experts at McAlpine Plant and Lifting, local authorities, utility providers, highways teams, neighbouring developments and specialist suppliers.

More than 100 people contributed to the planning and delivery of the works. From the earliest option studies to the final lift, every element depended on teams working together to solve problems, adapt to changing conditions and maintain a relentless focus on safety.

At the heart of that effort was our specialist Plant and Lifting Team. They spent well over a year evaluating options, challenging assumptions and breaking down an enormous engineering task into a series of smaller, manageable solutions. By integrating their specialist knowledge into our project team, we were able to smoothly execute such an ambitious operation.

The achievement is testament to our teams’ engineering expertise, planning capability and commitment to collaboration.