The city can expect to see three railway projects, all in the New Territories, starting from 2020 under a proposal set to underpin the next stage of rail development.
All three are likely to require huge subsidies due to the dispersed populations and low-density housing in the areas they serve, officials warn.
Two of the lines are domestic: a northern link, which will connect Kam Sheung Road and the Lok Ma Chau border checkpoint, and a Tuen Mun to Tsuen Wan link.
The third is a cross-border connection between the Hong Kong and Shenzhen airports. This will include two spur lines that extend to the West Rail and Tung Chung lines in order to maximise patronage.
The proposal comes as the New Territories' residential population is expected to jump 40 per cent by 2031, compared with 10 per cent in urban areas, due to new developments in Hung Shui Kiu, Kwu Tung North and Fanling.
The Transport and Housing Bureau launched a three-month public consultation yesterday to seek Hongkongers' views on whether they prefer road-based transport to railways in these areas. Railway lines are costlier and loss-making, as they have to be built across vast tracts of land that serve low-density populations.
The link connecting Chek Lap Kok airport and Shenzhen's Baoan airport via Qianhai appears to hold the greatest economic value, a transport expert says, pointing to the extensions to the West Rail and Tung Chung lines.
