Flying high at HK's Eagle's Nest Tunnel

摘要

Precision drilling is allowing contractors Leighton to meet the challenges of a major tunnel in Hong Kong. The company is excavating the exact shape needed along a constantly-changing curved alignment with a crossfall through difficult ground. Achieving the crossfall without removing any extra material is providing valuable savings for the client. "Excavation follows the crossfall, reducing the quantity excavated," says the project's chief surveyor Gordon Ferrier. Normal practice is to excavate a larger area and then fill in material later to provide the tilt of the crossfall. "The method we are using here allows simpler excavation and a smaller tunnel, providing savings for the client."