Development and application of underground space use in Hong Kong

Abstract Underground space has been utilised in Hong Kong for many decades. It has been developed through various phases of infrastructure development and improvement. The early forms of underground space construction were associated with war time protection and mining operations and this has extended with increased urban densification to numerous examples of underground basements that have incorporated car parks, retail and commercial underground spaces. Notable underground space also includes numerous road, rail and utility/service tunnels that comprise a network of over 500 km of tunnels in the city to accommodate essential services and transport. With the Mass Transit Railway (MTR) construction in the 1970s it kicked off a spate of excavation of underground space for metro stations and linking tunnel networks that has developed one of the most efficient and reliable metro systems in the world. The private sector has increasingly, over the last few decades, linked their commercial and retail properties to the MTR station network providing hubs of interest and commerce within the underground network. Since the 1990s, a few government “Not-In-My-Backyard” type facilities have been built in rock caverns to meet the needs of the community, including a sewage treatment plant, a refuse transfer station and an explosives depot.