The event re-telling of the Crucifixion of Jesus was instigated by Preston Guild, directed by Mark Murphy and hosted by Fern Britton for the BBC on Good Friday at Preston Bus Station. The outdoor and live mass participation elements of the event were produced by innovative arts / performance company Walk The Plank,
Each crucifix was 9m tall with a 4m cross piece, and was constructed on the top floor of the multi storey car park above the Preston Station.
The crosses were clad in wood, painted black, and erected one at a time using an electric chain hoist and self-climbing tower methodology. This was choreographed to happen while three short sections of pre-recorded drama were shown simultaneously on large LED screens, interlaced with the live action taking place in the bus station, which included the participation of thousands of local residents.
dbn was asked to help realise this very special scenic effect by Nick Clarke of Walk The Plank. dbn project manager Nick Todd set about designing the crucifixes and rigging system from Slick Mini Beam trussing.
The brief was that nothing should be visible above the car park's external parapet which was about a metre high and that the crucifixes should come into vision only when raised. All the engineering required for the lifts had to be at floor level and this was a major challenge.
Todd worked with Ian Hall and Chris Cronin of the Total Solutions Group and their structural engineers to design what was effectively a very low level ground support system. A test rig of the proposed lift procedure was built at dbn's warehouse in central Manchester to ensure that the concept would work before the design was signed off.
Once on-site, wind speeds were constantly monitored and trends logged with dbn's new Broadweigh wireless load and wind load monitoring system.
The large base structure with extended outriggers using dbn's own customised ground support base plates was built in the car park, also out of Mini Beam. This was extended back about 11 metres to brace between the front and rear walls of the car park, accommodating the three crucifixes in a horizontal position until the moment for their erection came.
The base of each of the three crucifixes was hinged at the front end and a 1 tonne motor attached. Due to the very limited space in front of the structure, a small de-mountable lifting block had to be installed at the front end of each one which, when the cue came, increased the chain height enough to allow the crucifix to be lifted. Even so, the dynamic load was about a tonne as the lift commenced. This lifting block was detached when the crucifix was in place, and additional guy wires attached to keep the erect crucifixes stable.
dbn's crew had a 10-minute window to raise each crucifix while the VT was playing back, and the two-person operation in reality took about two and a half minutes to achieve - getting the crucifix up and secured neatly and efficiently.
Says Todd, "We had to use every unusual and custom made mini-beam fitting that we own but it was an interesting project .... and we had a lot of fun."
(Jim Evans)
