The objective of this job was to provide the means of access for the plasterers, who were restoring the coving in The Royal Albert Hall. At the same time the normal operation of the venue was to remain uninterrupted by this refurbishment programme.
Opened in 1871 by Queen Victoria, The Royal Albert Hall has a distinctive roof structure, which, when surveyed, provided a particular challenge for Unusual. The part of the ceiling/roof to be refurbished was the outer coving and the method of access was to be a large working platform suspended on two rails, which were to be attached to the main roof structure. The platform would subsequently be moved around the dome on the rails, when each section was complete.
For aesthetic reasons, the inner rail was to follow the line of the scalloped ceiling and the outer rail was to follow the outer edge of the ceiling. The geometry of the two different elliptical shapes was such that the distance between the two rails was going to be inconsistent. The horizontal distance between the rails varies by approximately 1.8 metres, hence creating the need for a variable “axle” width.
Access into the roof void for materials was a 300mm square hatchway in the centre of the roof and 36 metres above the main arena floor. The outer platform ring was suspended from spreader beams, which had to be lifted through this small hatchway, before being fixed to the roof structure - in all, about 21 tonnes of steelwork was hoisted through this hatch. Small holes were drilled and lines dropped and surveyed using a theodolite from a datum point in the auditorium. Once verified, a bucket was attached to the line, hauled up tight to the plaster work and the full diameter hole was drilled. The waste plaster was retained by the bucket and a hole protector, designed by Unusual, was fitted to ensure that the job looked neat and tidy and that no plaster could fall into the auditorium.
Once the holes were finished, the spreader beam was clamped into place above the holes. Brackets and steel wire ropes were attached to them to receive the outer platform ring, each section weighing 300Kgs.
A similar procedure was carried out for the inner ring, but in this case there was sufficient height to install steel bridles to suspend the inner platform ring. Five beam sections were bolted together on the ground and lifted into position as one piece. Once the first section was secured in place, a painters cradle was fitted to the beam. This was used to access the end of the next piece to bolt it into position. Using lasers the new section was levelled and secured and the process was repeated until the ring was complete. All of the work was carried out overnight. The process of marking out the holes took about three weeks and over the next few months, 30 inner beams and 32 outer beams were lifted and secured into place. The total weight of beams and hanging points was in the region of 36 tonnes.
Once the two platform rings were finished, weight testing was carried out prior to assembling and suspending the platform skeleton. This assembly process was going to take a few sessions so at the end of each nightshift, the work in progress was flown out to enable the venue to function normally during the day.Once the skeleton was complete, the fitting out process began. This included giving the structure a waterproof floor, providing an access cradle to the platform and safe access systems to and from the cradle. The platform weighed 11 tonnes, when complete - which is roughly the same as a London double decker bus.
