BEIJING -- Beijing's first driverless subway line has started test runs, preparing to start service by the end of 2017.

The Yanfang line will serve the southwestern suburb Fangshan and be the first domestically developed automated subway on the mainland, according to First Engineering Co Ltd of China Railway Electrification Bureau Group, which is responsible for its construction.

Maximum speed on the line will be 80 km per hour, and trains will have a passenger capacity of 1,262.

According to the city's five-year plan on rail construction, the total length of operational rail in the city will exceed 900 km by 2020.

Up to 90 percent of the city proper will have at least one subway station within 750 meters, and rail access will reach all of the city's 16 urban and rural districts by 2020.

Driverless trains are planned for more lines, including an express line to the new airport being built in Daxing district.