A maglev train goes on trial in Beijing on August 5, 2017. [Photo/VCG]

2. Beijing

The capital city of China is the first city to have subway in 1965 in the country, and it has an urban rail transit system of 574 kilometers.

Beijing's subway system transported 3.66 billion passengers in 2016, the most in the worldwide.

The city's first mid-to-low-speed magnetic levitation track is going on trial in the beginning of August this year. The 10-kilometer line has 8 stations on a 20-minute journey. It is scheduled to open by the end of the year.

According to the city's plan approved by the State Council in 2015, Beijing will have 30 subway lines of 1,177 kilometers by 2020, and after that, it is expected to have 35 lines of 1,524 kilometers.