After breakthrough, workers will need about three months to break down the machine and reroute it to begin drilling the first bore's twin. Spoil is mucked out to the access shaft on a conveyor, which then carries it to the surface. At Tai Lam, where more space is available, Nishimatsu-Dragages built a series of settling ponds to clarify water before discharge. Water presents a different challenge for work being done in low-lying areas of the New Territories, where the viaduct, seven stations and a train depot are being built. Foundation work mustbe accomplished quickly during the fall to winter dry season.
Seasonal rains make it essential that contractors get out of the ground quickly.
Aggressive noise restrictions of 60 db for operating trains sent the contractor to redesign. The result is a system featuring a variety of sound absorbing plenums built on shorter, lighter spans with monolithic connections between piers and the deck structure. Rubber bearings installed under the floating slab track further reduce vibration. The addition of side panels went a long way to reducing sound butresulted in very high construction tolerances. The panels are designed to work with skirts extending below the train to capture or absorb sound.