The Greater Bay area is a region that includes Hong Kong, Macau and nine cities in China's southern Guangdong province.

China plans to expand its railway network, the second largest in the world, by one-third in the next decade and a half, as part of a long-term plan to rev up urbanisation and stimulate local economies.

The country aims to have about 200,000 kilometres of railway tracks by the end of 2035, including about 70,000 km of high-speed railway, according to the plan issued by state-owned China State Railway Group in August.

(Reporting by Judy Hua, Lusha Zhang, Ryan Woo and Gabriel Crossley; Editing by Himani Sarkar and Sherry Jacob-Phillips)