The Shenzhen-Zhongshan Link in South China's Guangdong Province, will open to traffic on June 30.

The Shenzhen-Zhongshan Link, a transportation hub project in the Guangdong-Hong Kong-Macao Greater Bay Area (GBA), opens to traffic at 3:00 pm on Sunday,with traffic flow exceeding 7,000 vehicles within the first hour of its operation, Xinhua News Agency reported.

The daily average traffic volume is estimated to reach 80,000 to 100,000 vehicle trips, and the link is expected to operate at full capacity upon opening, according to yicai.com.

The passage will significantly enhance economic and social connectivity, facilitating the movement of goods throughout the Pearl River estuary, promoting balanced development of the GBA, local transport authorities said.

Chinese President Xi Jinping on Sunday sent a congratulatory letter on the opening of the cross-sea passage. He noted that the project fully illustrates that Chinese modernization can only be achieved through solid work, according to Xinhua.

After the bridge commences operation, the travel time between Shenzhen and Zhongshan will be shortened from two hours to around just 30 minutes, greatly enhancing the connectivity and efficiency of the national highway network and transportation system in the GBA. 

Authorities said the toll for the entire route is 66 yuan ($9) per vehicle trip, Xinhua reported.

The bridge marks a significant improvement in connecting not only the GBA cities, but all of South China, bringing accessibility, convenience and speed to both travelers and businesses, local officials said.

The project, which integrates two bridges, two islands and an underwater tunnel, consists of a 24-kilometer-long eight-lane expressway with a speed limit of 100 kilometers per hour.

It is an important part of the national expressway network crossing the Pearl River estuary, about 30 kilometers south of the Humen Bridge and 31 kilometers north of the Hong Kong-Zhuhai-Macao Bridge, another mega cross-sea passage in the GBA.

According to Xinhua, the Shenzhen-Zhongshan Link, along with existing structures such as the Hong Kong-Zhuhai-Macao Bridge, will form a network of cross-sea and cross-river passages in the Greater Bay Area, boosting connectivity of the city clusters there, said Deng Xiaohua, head of Guangdong Provincial Communication Group Co.

A number of key innovations and technological breakthroughs were made in the process of project construction. The channel, touted as a marvel of engineering, is considered one of the most difficult cross-sea transportation projects ever completed in the world, taking seven years to build. 

It has set several world records, including being the world's first long-distance dual eight-lane submarine tunnel using immersed tubes, and the world's first underwater high-speed interchange connecting an airport and a highway.

A significant step toward China's goal of becoming a transportation powerhouse, the Shenzhen-Zhongshan Link also signals that the construction of the GBA has achieved fruitful results, experts said. The bridge is set to promote the smooth flow of technology, talent, and other resources within the region, Liang Haiming, chairman of Hong Kong-based China Silk Road iValley Research Institute, told the Global Times on Sunday.

The cross-sea link will accelerate the country's goal of building the GBA into world-class financial, service, shipping and innovation centers by 2030, Liang noted.

"This project not only enhances talent exchanges, cultural interaction, and tourism, but also boosts regional integration," said Song Shenyou, director of the Shenzhong Link administration center and chief engineer of the project, local newspaper Yangcheng Evening News reported.

Timothy Chui Ting-pong, director of the Travel Industry Council of Hong Kong, said that the project would spur Hongkongers' demand for same-day travel to Zhongshan city and surrounding regions. Chui told the Global Times that the number of tours to Zhongshan could double in July and August.

In addition to boosting tourism, experts said the road link will provide more options for local employment, lower living costs, and enhance the efficiency of the local supply chain. It will also help Hong Kong to maintain its position as an international trade and financial hub, the expert said.