This project required the diversion of all services in accordance with new taxiway designs which had been drawn up to enable larger planes to use the airport. Bravo Taxiway was realigned and upgraded to accommodate the Code F aircraft (A380). Careys Civil Engineering was awarded the contract to replace 1843 linear metres of storm water drainage and 35 manhole and catch pits.
Bravo Taxiway is the inner taxiway of a twin system which feeds onto and from one of two main runways. This critical location required a high standard of awareness of the environment, with particular attention paid to potential FOD and height restrictions due to the runway side slope.
Due to airport emergency response times, an emergency access route had to be maintained and clearly marked at all times, thus allowing emergency service access should an aircraft be occupying the outer taxiway. This factor was built into all phases of planning and logistics.
One challenge for the designers was the depth of the diverted 900mm and 1050mm drainage, as the new pipes were fixed at each end and already relatively shallow. The diversion route added circa 50lm to the run, creating a flat system. The greater challenge was the structural integrity to accommodate a pavement designed for Code F aircraft. The solution was to fully encase the pipes with reinforced concrete. All other pipes were laid in the traditional manner with plain concrete surround.
The drainage system that was being replaced and upgraded served the Northern runway and therefore had to be maintained around the clock. This was achieved by detailed sequencing and planning to reduce risk, with correctly sized over pumping being installed when one of the multiple connection changes took place.
As several of the manholes required for the project were located outside of the site perimeter, these had to be constructed during limited possession night shift periods. These works were located within the taxiway strip, requiring each manhole area to be brought back to ground level and protected to prevent accidental entry at the end of each shift.