China's first tunnel beneath the Yangtze River opened to traffic on Sunday in central China's Hubei Province.

It is 3.63-km long and has four lanes. Traffic began to go through the tunnel at about 10:00 AM in Wuhan City.

Travel time between the city's major areas -- Wuchang, where government offices and universities are based, and Hankou, the business center, is now seven minutes. It used to take half an hour.

Around 50,000 vehicles can travel through the tunnel going 50 kilometers per hour every day. It can withstand flooding (300 year-flood plain) and an earthquake measuring up to six on the Richter scale, according to Wuhan's vice mayor Yin Weizhen.

The 2.05 billion yuan (US$299.6 million) project began in November 2004. It was part of the city's efforts to improve transportation infrastructure and relieve congested roads.

Wuhan, capital of Hubei Province, is one of the largest cities in central China with a population of eight million. It is the center of five railway lines, six expressways and several highways. The city serves as the gateway to China's hinterlands and is nicknamed the "thoroughfare to nine provinces".

Traffic in Wuhan relies on ground transportation networks and ferry service. Before 1957, people had to cross the river using only a ferry. After that time, the Wuhan highway-railway bridge was put into operation. However, the bridge has been overburdened with about 100,000 motor vehicles and 300 trains crossing it each day.

As a milestone in the history of transportation across the Yangtze River, the new road tunnel was constructed with the most advanced engineering technology in complicated geologic conditions, said Wang Mengshu, a member of the Chinese Academy of Engineering.

"The resources used in the construction will provide valuable references for other tunnel projects and will further promote China's river-crossing transport development," Wang said.

The 6,300-km long Yangtze River is a major transport link between west and east China. More than 100 bridges across the Yangtze River are currently in use.

Construction on another two tunnels beneath the Yangtze has been underway in Shanghai and Nanjing, the capital of the eastern Jiangsu Province.