Dalian has started construction of an undersea tunnel to ease increasing traffic jams.

Located at the southern tip of the Liaodong Peninsula, the coastal city has only two main highways connecting its downtown area with its economic development area and accessing other cities in Northeast China.

The 5.4-km-long tunnel, across Suoyu Bay, will provide a third transportation artery.

Yang Lijun, an official with the city's construction department, said the dual three-lane carriageway is due to be completed in 2019.

"It will not only relieve traffic congestion but also promote the development of the nearby East Harbor Commercial Area, the Suoyu Bay Commercial Area, and Xianglujiao Logistics Park," he said.

The tunnel and facilities will involve an investment of around 7.2 billion yuan ($1.19 billion).

Yang said the undersea section of the tunnel will be 2.7 km long and will use the same "immerse cube method" engineering technology, as the Hong Kong-Zhuhai-Macao Bridge did.

The method sees the production of all components on shore before assembling and installing them into the pre-built foundation trench on the seabed.

"Compared with drill-explosion method, it is a more advanced technology. More importantly, it has been successfully applied in the construction of the bridge, and that gives us confidence," Yang said.

He said preparation work will be completed this year.

The tunnel requires 15 components, each 180 meters long and 35 meters wide.

When the tunnel is put into operation, it will take only 10 minutes to drive through.

"That would be great," commuter Li Xianfeng said. "You know, the existing 18-km-long road along the seaside takes about 40 minutes or even more to drive in rush hours."

However, other residents writing on the Sina Weibo, a Twitter-like platform, have expressed concerns.

"When Donglian Road (the second major artery in and out of downtown Dalian) opened in 2009, experts said traffic jams would be greatly reduced. Only a few years later, we need a new option. The new projects cannot catch up with the increasing number of new vehicles," a user named Pinmingdl complained.

Statistics show there were more than 1.2 million vehicles in Dalian at the end of 2013, almost triple the number in 2008.

Sun Mingnan, a local legislator, suggested optimizing public transportation networks to get more residents to take buses instead of private cars.

"People will choose the bus if it is more convenient and comfortable," he said.

At present, Dalian has 23 designated bus lanes during rush hours, and more public transport improvements are expected in the coastal city.

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