What lies beneath? A decade of underground construction in Hong Kong

Over the past decade Hong Kong has seen a rapid expansion in the use of underground space for Civil Engineering infrastructure projects (Fig 1). Forty-eight kilometres of rail tunnel has been or is in the process of being constructed with associated shafts (Fig. 2) for access and ventilation and mined caverns for stations (Fig. 3). The catalyst for this expansion may be due to the integration of the Hong Kong Special Administrative Region with China which commenced in 1997 (with the handing back of Hong Kong and the New Territories to China) and has accelerated over the last decade in line with the global aspirations of China. This integration has been the catalyst for: three new major road border crossing projects (Deep Bay Link, Hong Kong to Macau Bridge and, Liantang/Heung Yuen Wai crossing) and; connection into the mainland express rail link (Hong Kong High Speed Rail Project) (Fig. 1). The population has also risen over this period from c.6.9M in 2005 to c.7.3M in 2016 (tradingeconomics 2016) fuelling in part the expansion of mass transit rail systems: the Kowloon Southern Link (3 km – complete); the West Island Line (3km - complete); Shatin to Central Link (17km - under construction); the South Island Line East (7km - under construction); the Kwun Tong line extension (3km - under construction) and the Hong Kong Express Rail Link (26km - under construction) (Fig. 1). Pressure on valuable land resources has seen the emergence of the innovative use of underground space for: explosives magazines; sewage treatment systems, service reservoirs (Fig. 4); urban drainage and flood protection projects (Fig. 5) and, new road networks such as the Central - Wan Chai Bypass (Fig. 6).

This paper presents a photographic record of some of the major underground projects constructed between 2006 and 2016. This record has been collected during student field study tours run by the University of Portsmouth for both undergraduate and post graduate students of Engineering Geology and Geotechnics and Engineering Geology degrees respectively. A brief overview of the relevant facts regarding Hong Kong climate, topography and geology are presented. This is followed by a review of typical construction methods used to create underground space in Hong Kong. Pertinent geological context is given in the text or as supplementary data to the photographs presented.