Billed as the world's longest sea bridge connecting Hong Kong, Macau and mainland China, it has been touted by supporters as an engineering wonder.
But critics say the multi-billion dollar infrastructure mega-project is politically driven and a costly white elephant.
Dogged by delays, budget overruns, accusations of corruption and the deaths of construction workers, there is little prospect it will open by the end of 2017 as hoped.
Building started in 2009 on the 55-kilometre (34-mile) crossing, which includes a snaking road bridge and underwater tunnel, linking Hong Kong's Lantau island to the southern mainland Chinese city of Zhuhai and the gambling enclave of Macau, across the waters of the Pearl River Estuary.
Officials say it will boost business and cut travel time, but opponents in Hong Kong see it as another attempt by Beijing to tighten its grip on the semi-autonomous city.
Hong Kong enjoys rights unseen over the border but challenges from young pro-democracy activists and the emergence of a fledgling independence movement have riled Chinese authorities, who have warned they will not tolerate threats to China's sovereignty.
The Chinese government is "trying to blur the boundaries between Hong Kong and the other parts of the mainland", said pro-democracy lawmaker Kwok Ka-ki, who sits on the legislature's transport panel.
With its dire housing shortage and growing wealth gap there are also questions over whether the bridge is a good use of the Hong Kong government's money -- all three jurisdictions pay a portion of the costs.
The total price tag for the project, which includes artificial islands, link roads and new border-crossing facilities, is unclear but some estimates run to over 100 billion yuan ($15.1 billion).
"Hong Kong doesn't really need it -- we've got air, land and sea connections to the mainland," said pro-democracy lawmaker Claudia Mo, also on the transport panel.
"To Beijing it's one big gigantic symbol to link Hong Kong to the mainland."
- Loyalty test -
Officials cast the bridge as part of the Greater Bay Area project to create an economic hub linking nine southern mainland cities to Hong Kong and Macau, also a semi-autonomous Chinese territory.
Pro-Beijing Hong Kong lawmaker Regina Ip says the bridge will help connections all the way to Southeast Asia, as part of China's "One Belt, One Road" initiative to link with Africa, Asia and Europe through a network of ports, railways, roads and industrial parks.
"Although we have a boundary, we are still part of China and economic integration has been happening in a market-driven way for the past few decades," Ip said of Hong Kong's position.
"We cannot go against this trend."
However, some analysts including commentator Stephen Vines see the billions being spent on the bridge and other infrastructure links, including a new high-speed rail connection, as predominantly a political calculation -- not only by the Chinese central government, but also by local authorities.
"The political leadership in Hong Kong wants to prove its loyalty to the leadership in Beijing," Vines said.
Ip told AFP she expects the bridge crossing to open in the first quarter of 2018. Hong Kong's highways department said it could not give a time frame.
- View from the ground -
Officials put the current cost overrun of the main bridge section at 10 billion yuan ($1.5 billion), partly driven by engineering challenges, which have included problems with the drifting of reclaimed land.
The original cost of that section, including bank loans, was 37.7 billion yuan.
There have also been safety concerns -- 19 lab workers have been charged over faking concrete test reports, with one man jailed earlier this month.
Since 2011, 369 industrial accidents and nine deaths have been recorded, according to the labour department.
Hong Kong residents are split over whether the project is worthwhile.
"I don't think it's a good thing because it's been under construction for a long time and the cost is high," says Iris Lam, 28, who works in sales.
Student Saoirse Barry, 17, described it as "another tentacle of power" for Beijing.
But Silvia Lee, 55, who runs a squid and fishball stall in the Lantau village of Tai O, which overlooks the bridge, said it could be a boost.
"If it's more convenient for people to come here, there will be benefits to the economy," she told AFP.
For Tai O resident Wong Kam Fook, 85, the crossing is now on his bucket list.
"I'm in my 80s and I'm about to die, so if I can travel down that bridge then I will do it!" he told AFP.