BEIJING -- Workers have started to lay tracks for a subway line connecting downtown Beijing with its new international airport, local authorities said Wednesday.

Stretching over 41 kilometers through the southern part of Beijing Municipality, the new line will link Beijing Daxing International Airport with Caoqiao station in Fengtai district, where passengers can transfer to subway line 10, according to the Beijing Major Projects Construction Headquarters Office.

The new line will be put into service at the end of September 2019, when the airport starts test operation.

New technologies such as self-driving systems will be used on the line, the office said.

The new line is part of an integrated transportation network, which will combine subways, expressways, intercity railways and high-speed railways with the new airport at the center.

Beijing Daxing International Airport, located 46 kilometers south of downtown Beijing, is designed to take pressure off overcrowded Beijing Capital International Airport in the northeastern suburbs. It sits at the junction of Beijing's Daxing district and Langfang, a city in neighboring Hebei province.