HANGZHOU -- The first metro line in Hangzhou, capital of east China's Zhejiang province, officially opened on Saturday in a bid to help ease traffic congestion.

The 48-km-long Metro Line One has 31 stations and 48 trains with a departure every 10 minutes from 6:30 am to 8:30 pm each day.

Zhejiang Governor Xia Baolong inaugurated the line, which is designed with a daily passenger capacity of 287,000.

Shao Jianming, chairman of the Hangzhou Metro Group which is behind the project, said that the 24-billion-yuan ($3.85 billion) line is expected to ease traffic woes in the city, which has a population of more than 8.7 million.

"Hangzhou's metro network, upon its full completion in 2050, will comprise 40 percent of the city's public transport," he said.

Hangzhou will build 10 metro lines by 2020 with a combined length of 375 km and by 2050, it will have a total of 13 lines.

Shao said the Metro Line One, which took five years to construct, boasts complex technology as it runs underneath the West Lake, the Qiantang River, the Grand Canal and several railways.

The line will be jointly operated by the Hangzhou Metro Group and the Hong Kong-based MTR, according to a deal signed in July on a 51-49 joint venture to manage the line for 25 years.

Huang Kunming, secretary of the Hangzhou Municipal Committee of the Communist Party of China, called Saturday's launch "just a beginning" of Hangzhou's metro line construction boom.

Tickets, which are due to go on sale at 2:30 pm, are set to vary from 2 to 8 yuan.

Rapid expansion of urban population and the number of cars have driven Chinese city managers to resort to subway systems to ease worsening congestion on the ground.

Harbin, capital of northeastern province of Heilongjiang, announced on Saturday that its first metro line will be launched next year after four years' construction.

The line, which will have China's first cold-resistant metro cars, will be 17.47 km and have 18 stations, according to the Harbin Metro Group.

The line is expected to carry 215,000 passengers every day.

The metro cars, measuring 120 meters each and equipped with heating devices, will travel at 35 km per hour.