The installation of nearly 40km of high voltage (HV) and low voltage (LV) cables are integral to the ‘power on’ of Terminal 2, and as part of these works, FP McCann has manufactured and delivered 9 large precast concrete cable drawpit chambers which sit under the link bridge to the first of the aircraft piers. The precast concrete chambers protect these cables in safe, readily accessible housing, and have been designed to F900 loading due to the location of the precast concrete chambers. This means that the precast concrete chambers and their associated covers are capable of withstanding 900kN test loads.With site constraints and very tight vehicle access, each of the 9 precast concrete chambers were supplied on a just-in-time basis from FP McCann’s Byley precast factory in Cheshire. Each chamber consists of a base unit and a number of riser sections which vary in weight from 6 tonnes to 15 tonnes. The top riser units all have castellated tops to enable steel cross beams and covers to be cast on site.
The precast concrete chambers themselves range in dimensions from 3m x 3m to 6m x 3m and all are 1.75m deep. Each chamber has duct couplers cast in at the factory as determined by the specified bespoke layout, thereby enabling a quick installation process.
In addition, steps have been cast into each section and a sump formed in the chamber base units, whilst a waterproof bitumen coating has been applied to all external faces.
Commenting on the chamber installation, Section Engineer for Laing O’Rourke, Giedre Jurkonyte, said: “As we were on a very tight schedule, we chose the offsite built precast option to speed up installation. Precast elements are a more environmentally sustainable option, as less concrete is used and, as a result, FP McCann was able to reduce the wall thickness from 400mm to 300mm. There was no concrete wastage and vehicle footprint was minimised.”
The Manchester Airport Transformation Programme includes the Terminal 2 extension, a 3,800-bay multi-storey car park, the addition of three new piers and extension to the existing forecourt.