As of late, plans for more rail links in the Pearl River Delta, also known as the Greater Bay Area, are popping up around the Chinese rail world. Here’s a look at what is being proposed, as per part of the regional plan.
Note: As with everything China, the following may be subject to change!
Second Hong Kong High Speed station
This isn’t exactly High Speed as in G trains, but is likely for intercity rail and is expected to go from the also-new Shenzhen Port (深圳港) station in Guangdong to Hong Kong’s Chep Lap Kok International Airport on the island of Lantau. That airport, too, is being expanded with a second terminal and a third runway. Hong Kong Airport station is planned to be a terminus, not unlike West Kowloon, so if Customs & Immigration colocation worked at West Kowloon, one wouldn’t rule it out for the airport (rail station-wise).
Furthermore, there could be a future link within Guangdong to go from Shenzhen Port station to the other side of the delta, closer to the Zhuhai end.
Macao High Speed station
Macao is also getting its High Speed station, this time a “decent” HSR station (as it is on a line planned as “full” High Speed as opposed to merely “intercity” High Speed). This will be a new HSR line, first planned to start just west of Zhuhai, then eventually extend north to Zhongshan and eventually Guangzhou.
At present, Macao’s link to the national HSR network is by way of Zhuhai Railway Station, which is on the Guangdong side of Gongbei (拱北) / Portas do Cerco (關閘). (Earlier on, you had to catch a taxi to the very remote Zhuhai North station!) The new HSR station will fully make use of Hengqin (横琴) Island (which mostly belongs to Zhuhai, but has a Macanese exclave on it). Trains are expected to go from Zhuhai Hengqin station east to Macao station (closer to the airport than the old city).
Again, Macao High Speed station is a terminus, so Customs & Immigration colocation could be an option here as well, if West Kowloon is any indication. (The Macanese seem to be happier with this — there are reports that Mainland and Macanese immigration are next to one other at the Mainland-to-Macao port of entry on the Hong Kong-Zhuhai-Macao Bridge.)
Alas, there appears to be no real rail link between the two Chinese special administrative regions… as of yet…