A think tank on Thursday proposed building an inter-airport railway between Hong Kong and Shenzhen to better integrate the SAR into the mainland’s high-speed rail network.

According to the Our Hong Kong Foundation (OHKF), the link would shorten the journey between the two airports to 40 minutes, down from the current fastest travel time of 70 minutes possible through a combination of ferry and land transport.

It is estimated that the proposed railway would generate an economic benefit of HK$87 billion and boost annual airport passenger throughput to 118 million by 2040, compared to 102 million if no action is taken.

Jason Leung, head of land and housing for OHKF, said approximately 24 million passengers would take the railway per year.

“The majority will come from the catchment... the passengers who will be using the Hong Kong airport originating from the Greater Bay Area, or they come from further inland cities,” he said.

“The second segment is that transit or transfer passengers who are transferring between Hong Kong and Shenzhen airports. These could also be mainland tourists coming to Hong Kong for sightseeing, business purposes and leisure, or they could also be Hong Kong residents who are going to the mainland.”

The foundation’s vice-president, Ryan Ip, warned that Hong Kong airport is already seeing slow growth in both passenger and cargo volume and risks losing its edge as an international aviation hub if it fails to align with the nation’s air-to-rail transport strategy.

“We are being overtaken by many of our neighbouring airports, including Singapore, and even Guangzhou and Shenzhen in terms of passengers throughput,” he said.

“The 14th Five-Year Plan had a clear target that 80 percent of the airports within mainland China has to be connected to the high-speed rail. I think Hong Kong should not be left behind on that.”

The foundation said it has not come up with an estimated cost for the rail link, saying the first step is to reach a social consensus on the necessity of the project.

The idea of an airport-to-airport rail link was first proposed by the government over two decades ago in the Railway Development Strategy 2000, but concerns were raised over its viability and necessity at the time.