ALE has overseen the move a gantry crane over live railway lines

ALE has overseen the move a gantry crane over live railway lines, as part of London’s HS2 project.

The gantry crane, which weighed 290t, was due to be moved into position for demolition in North London. Costain Skanska contracted ALE to devise a method of moving the crane, with stipulations relating to the location of the crane that the ‘state of the crane’ could not be altered in any way, and that there could be no impact on the train operations.

ALE employed a system that differed to the conventional approach for moving similar gantry cranes. A bespoke bracket was designed that could lift the crane the jacking points underneath the bogies. This design meant that the state of the crane was not affected, and that its structure would not be subjected to stresses beyond its design criteria, which may have caused the crane to become unstable during the move. This was due to two of the crane legs being secured with a pin joint, which had the potential to swing—an issue resolved by the bracket solution.

ALE obtained a rail possession on the quietest day of 2018—Christmas Day—to avoid any risk to active trains. The company used 36 axle lines of SPT in a 2 x 2 file 18 configuration, with the bespoke brackets attached under the bogies to manoeuvre it approximately 40m clear of the rails. The crane was then placed onto a specially-made mock rail line foundation. The move was completed in 11 minutes and, as the project was located in a residential area, to team returned a few weeks later to remove all the equipment off site, to avoid disruption.

Project manager David Trigg said: “We faced more challenges than the usual port cranes moves we perform, which are typically rigid and don’t have the load bearing pressures capped. Because of the complexities involved in this project, it was hugely rewarding to see all of the detailed planning come together.

“By working with our in-house engineering experts in the UK, our bespoke new brackets enabled the successful and safe completion.”