China Opens World's Longest Sea Bridge in Mega-Project to Connect 70 Million People

China has officially opened the longest sea-crossing bridge in the world in its southern city of Zhuhai, connecting mainland China to Hong Kong and Macau.

The 34-mile road bridge has been under construction for almost nine years and is a central element of Beijing's project to link what it calls its Greater Bay Area, the BBC reported.

The Greater Bay Area will cover 21,800 square miles and encompass 11 cities and some 68 million people in mainland China and the semi-autonomous provinces of Hong Kong and Macau.

President Xi Jinping inaugurated the $20 billion bridge, telling hundreds of guests: "I declare the Hong Kong-Macau-Zhuhai bridge officially open." The structure, which snakes over the vast Pearl River Delta, will be opened to regular traffic for the first time on Wednesday.

The new link comprises 400,000 tons of steel—more than four times the amount used for San Francisco's Golden Gate Bridge, according to CNN. It has been built to survive magnitude 8 earthquakes, super typhoons and even impacts from the world's largest cargo ships. To avoid the Delta's busiest shipping lanes, the bridge becomes an underwater tunnel for a 4-mile stretch between two artificial islands.

The roadway will be policed using high-tech monitors keeping track of drivers' heart rates, blood pressure and even the number of times they yawn. If a driver yawns more than three times in 20 seconds, "yawn cams" will raise an alarm to authorities, The Guardian reported.

Supporters of the project claim it will help stimulate the local economy by reducing the travel time between the three cities, encouraging deeper business links and easier tourism. The trip between Zhuhai and Hong Kong would have previously taken around four hours, but officials said it would now be cut to around 30 minutes.

But the benefits will be felt across the region, Zhuhai's transport secretary Frank Chan said, suggesting the bridge would bring "the western Pearl River Delta region within three hours' drive from Hong Kong."

Opponents of the mega-project argue it is unnecessary and too costly. A new bridge linking the city of Shenzhen—which connects Hong Kong to mainland China—and Zhongshan just north of Macau, is expected to be completed by 2024.

This new structure plus improved high-speed rail links are expected to cut use of the Zhuhai connection by more than 26 percent within just 20 years. For opponents of the Communist Party, the bridge is as much a political project tying Hong Kong closer to the central government as Beijing attempts to rein in pro-democracy and pro-independence ambitions within the territory.

For all the talk of improved connections, private car owners from Hong Kong will only be able to cross the bridge with a special permit issued on a quota basis and after paying a toll. Even then, most will have to park at the port and use private shuttle buses or special hire cars to continue their journey once through immigration.

The project experienced multiple delays during its construction and has been criticized for its poor safety record, with at least 18 workers believed to have died and hundreds injured since work began. There were even allegations made last year that data from concrete safety tests of the bridge were falsified between 2013 and 2016. Charges were eventually brought against 19 staff members of a firm contracted to carry out the tests, The South China Morning Post reported.

Meanwhile, conservationists have warned that the bridge could be catastrophic for the Chinese white dolphin population, an endangered species native to the Pearl River Delta region.

The World Wide Fund for Nature told the BBC that the number of dolphins seen in waters near Hong Kong has fallen from 148 to just 47 over the past 10 years, and warned that the effect of the bridge could send numbers even lower.

This article has been updated to include more information about safety concerns during the construction of the bridge.