Innovation below-the-hook in lifting operations can reduce downtime and enhance safety on construction projects in urban environments, as proved by a lift in a narrow London street last December.
Safe application of tower cranes can be particularly challenging in high-rise development, which is inherently concentrated in areas where busy streets, restricted access and congested sites are prevalent. This was certainly true of a project near the famous Fleet Street in England’s capital city, where Modulift engineers were called onto site by LSC Facades.
A complex rigging solution was required to lift pallets from a lorry in Fetter Lane, using a tower crane that was already on the construction site. Below-the-hook equipment manufacturer Modulift designed a one-over-two-over-four spreader beam configuration to lift four non-standard pallets for the contractor, which provides exteriors for a variety of projects, including a number of landmark public buildings.
The loads were fixed to pallets measuring approximately 3.5m x 1.5m with the heaviest weighing 950kg. The narrow street combined with the height of lift and limited visibility for the tower crane operator presented challenges. The street was not closed during the lifts but traffic was not allowed to pass during lifting operations.
Tom Cox, production supervisor, Modulift, explained that as the load was “basketed”, it had the potential to be unstable, thus, the Modulift engineering team leaned towards the one-over-two-over-four spreader beam configuration.
He said: “This configuration creates a statically determinate or balanced lift. There is limited skewing so the load is evenly distributed, which was especially important in this case given the limited dimensions we had to work with because of the narrow street and surrounding environment.”
He added: “Although it is fairly unusual to see this rig used in an urban construction scenario like this, it is a common solution for lifting sections of modular buildings. One-over-two systems are particularly commonplace in the oil and gas sector for skid lifting systems where there are four lifting points.”
The spreaders were supplied from stock, further simplifying the rigging arrangement. The rigging was setup in under an hour, although the spreader beams were assembled prior to despatch to the customer for ease of transport and to utilise the most cost-effective method of delivery for LSC Facades.
Modulift personnel were on site to conduct training and oversee the lifts when four pallets were moved in one day on 23 December, while the same rigging formation will be used when additional batches of facade materials arrive in the coming weeks. In the meantime, the rig has been stored fully assembled, taking up minimal space on LSC Facades’ busy construction site.
LSC Facades were familiar with Modulift having taken earlier delivery of a beam from the manufacturer, on hire from another supplier.