Aerial photo taken on June 3, 2020 shows a BYD SkyShuttle train during a trial operation in Bishan District of southwest China's Chongqing. Chongqing's first SkyShuttle rail transit project has been unveiled recently, featuring electric-powered, rubber-wheeled trains running on a 15.4-km rail line with 15 stations. The project will provide passengers with quiet and safe travel services upon its estimated public operation in September 2020. (Xinhua/Liu Chan)

A BYD SkyShuttle train is seen during a trial operation in Bishan District of southwest China's Chongqing, June 3, 2020. Chongqing's first SkyShuttle rail transit project has been unveiled recently, featuring electric-powered, rubber-wheeled trains running on a 15.4-km rail line with 15 stations. The project will provide passengers with quiet and safe travel services upon its estimated public operation in September 2020. (Xinhua/Liu Chan)

Aerial photo taken on June 3, 2020 shows a BYD SkyShuttle train during a trial operation in Bishan District of southwest China's Chongqing. Chongqing's first SkyShuttle rail transit project has been unveiled recently, featuring electric-powered, rubber-wheeled trains running on a 15.4-km rail line with 15 stations. The project will provide passengers with quiet and safe travel services upon its estimated public operation in September 2020. (Xinhua/Liu Chan)

Aerial photo taken on June 3, 2020 shows a BYD SkyShuttle train during a trial operation in Bishan District of southwest China's Chongqing. Chongqing's first SkyShuttle rail transit project has been unveiled recently, featuring electric-powered, rubber-wheeled trains running on a 15.4-km rail line with 15 stations. The project will provide passengers with quiet and safe travel services upon its estimated public operation in September 2020. (Xinhua/Liu Chan)

An engineer conducts electrical tests on a BYD SkyShuttle train during a trial operation in Bishan District of southwest China's Chongqing, June 3, 2020. Chongqing's first SkyShuttle rail transit project has been unveiled recently, featuring electric-powered, rubber-wheeled trains running on a 15.4-km rail line with 15 stations. The project will provide passengers with quiet and safe travel services upon its estimated public operation in September 2020. (Xinhua/Liu Chan)

Aerial photo taken on June 3, 2020 shows a BYD SkyShuttle train during a trial operation in Bishan District of southwest China's Chongqing. Chongqing's first SkyShuttle rail transit project has been unveiled recently, featuring electric-powered, rubber-wheeled trains running on a 15.4-km rail line with 15 stations. The project will provide passengers with quiet and safe travel services upon its estimated public operation in September 2020. (Xinhua/Liu Chan)

Aerial photo taken on June 3, 2020 shows a BYD SkyShuttle train during a trial operation in Bishan District of southwest China's Chongqing. Chongqing's first SkyShuttle rail transit project has been unveiled recently, featuring electric-powered, rubber-wheeled trains running on a 15.4-km rail line with 15 stations. The project will provide passengers with quiet and safe travel services upon its estimated public operation in September 2020. (Xinhua/Liu Chan)

An engineer tests the autopiloting system of a BYD SkyShuttle train during a trial operation in Bishan District of southwest China's Chongqing, June 3, 2020. Chongqing's first SkyShuttle rail transit project has been unveiled recently, featuring electric-powered, rubber-wheeled trains running on a 15.4-km rail line with 15 stations. The project will provide passengers with quiet and safe travel services upon its estimated public operation in September 2020. (Xinhua/Liu Chan)

A BYD SkyShuttle train is seen during a trial operation in Bishan District of southwest China's Chongqing, June 3, 2020. Chongqing's first SkyShuttle rail transit project has been unveiled recently, featuring electric-powered, rubber-wheeled trains running on a 15.4-km rail line with 15 stations. The project will provide passengers with quiet and safe travel services upon its estimated public operation in September 2020. (Xinhua/Liu Chan)