The Hong Kong-Zhuhai-Macau bridge, the central plank of plans to integrate China's Pearl River Delta cities with Hong Kong and Macau, will start operations today after it was launched yesterday by Chinese President Xi Jinping.
Mr Xi declared open the 55km bridge at a ceremony in southern mainland city Zhuhai, attended by leaders of Hong Kong and Macau.
The US$20 billion (S$27.6 billion) bridge, hailed as an engineering wonder, joins two former European colonies to the Pearl River Delta in Guangdong to form the Greater Bay Area that comprises 11 cities and a combined population of 68 million.
The aim is to create a single market by capitalising on the bay area's expertise in infrastructure, finance, manufacturing and technology by reducing trade barriers to promote cross-border business. This could rival other bay areas in San Francisco, Tokyo and New York.
Mr Xi, who did not make a speech at the bridge's opening, is on a visit to Guangdong.
His presence at the opening was "a symbolic gesture from the top leadership" to mark the revitalisation of the Pearl River Delta area, which has fallen behind the other Chinese cities, said Professor Willy Lam of the Chinese University of Hong Kong.
Mr Xi's visit, at a time when China faces slower growth and a trade war with the US, has drawn comparisons with the late leader Deng Xiaoping's southern tour in 1992.
Associate Professor Hoo Tiang Boon of the S Rajaratnam School of International Studies said: "Some people have made it up to be analogous to what (former leader) Deng Xiaoping did when he visited the south - basically to send a message that China will not waver on reforms and will continue to further liberalise its economy."
China will mark the 40th anniversary of reform and opening-up in December.
Yesterday, Chinese Vice-Premier Han Zheng, who handles Hong Kong and Macau affairs, said the bridge symbolises China's transition into a world power. He noted that it is the first massive infrastructure project between Hong Kong, Macau and Zhuhai.
The opening of the bridge will boost interaction among residents, bring economic benefits and raise the combined competitiveness of the three cities, he added.
But critics see the bridge, the latest mega infrastructure project linking Hong Kong to the mainland after the US$11 billion Hong Kong High Speed Rail launched last month, as part of China's attempt to bind the city more closely to the mainland.
The new 55km crossing took nine years to build, and overran its budget after a two-year delay. It is the world's longest sea bridge and 20 times as long as San Francisco's Golden Gate Bridge.
With the bridge, travelling time has been shortened significantly. It will now take just 45 minutes, down from four hours, to get from Zhuhai to Hong Kong International Airport.
Hong Kong leader Carrie Lam said the bridge has created an ideal living environment where the three cities are within one hour's reach of one another, providing a sound foundation for the development of the Greater Bay Area.
"It is with this in mind that the Hong Kong government took the opportunity to propose the Lantau Tomorrow Vision, to create a better future for Hong Kong," she said.
In her Oct 10 policy address, Mrs Lam unveiled a proposal to reclaim land to create new islands around Lantau to build homes on the man-made islands and create jobs as part of a longer term growth strategy.
Local media yesterday reported some concerns about the need to get special permits or clear customs for users of the bridge.
Vehicles have to pay a toll of between 60 and 300 yuan (S$12 to S$60) to use the bridge. Passengers have to take public transport to the respective boundary crossing facilities, go through Customs and take private shuttle buses before switching to local transport.