China's longest metro loop line opened in full on Thursday in Wuhan, Hubei province, linking seven central districts and two major railway stations.

The 59.9-kilometer Line 12, confirmed as the country's longest metro loop by the China Association of Metros, has 37 underground stations. A complete trip around the loop takes about 96 minutes, and passengers can transfer to 11 other operating metro lines.

The opening of the line's second phase completed the loop, following the launch of the first section on May 1.

The line connects Hankou, Wuchang and Hanyang, three areas of Wuhan separated by the Yangtze and Hanjiang rivers. It gives passengers more options for traveling across the city and reaching Hankou and Wuchang railway stations.

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A key part of the route is a roughly 4-km tunnel beneath the Yangtze linking Kepu Gongyuan and Danshuichi stations. It is the country's longest metro tunnel crossing the Yangtze, according to the State-owned Assets Supervision and Administration Commission of the State Council.

Built by China Railway 14th Bureau Group, the tunnel provides a direct metro connection between Qingshan and Jiang'an districts on opposite banks of the river.

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Line 12 also uses fully automated trains that can start up, conduct checks and return to the depot after service without manual operation. Staff at the control center can take over remotely when needed.