Leighton Asia, with its partner, is one of the contractors constructed a 400,000 sqm underground terminus includes nine long-haul and six shuttle platforms, customs and immigration facilities, departure lounges, duty free and other retail outlets on four levels. Utilising a combination of conventional bottom-up and top-down construction methods, over 1.7 million cubic metres of earth will be excavated, 600,000 cubic metres of concrete placed and 150,000 tonnes of steel reinforcement will be used in the construction of the 30 metre-deep underground terminus.