His comments came after chief executive John Lee Ke-chiu said the government is open-minded about the rail transit system from a mainland company, as lawmakers called for the technology to be adopted in Hong Kong.

SkyShuttle is a driverless railway system with a small dynamic envelope and tight turning radius that runs on electricity.

Chan, also the former president of the Hong Kong Institution of Engineers, told a radio program this morning that the high-developed Kowloon East has limited ground and overhead space, while the development of underground space would come with a large price tag.

He said regardless of how green and innovative the Skyshuttle is, the prerequisite of building the railway system is having sufficient space.

“Even if the railway is built overhead, authorities will have to think of ways of delivering commuters from the ground…there is also no space for the construction of any emergency exits,” he added.

Meanwhile, Lawmaker Frankie Ngan Man-yu of the Democratic Alliance for the Betterment and Progress of Hong Kong, an advocate of the Skyshuttle plan in the city, admitted there was limited space on Kwon Tong Road.

He said the railway could go through areas attached to the main road to ensure enough space for the construction, providing smooth transport for residents in Kowloon East.

Ngan also noted that the Skyshuttle developed by mainland firm BYD is capable of steering through narrow and winding terrain, with its capacity a good fit for serving the area.