Passengers board a CETROVO 1.0 metro train on the Metro Line 1 in Qingdao, east China's Shandong Province, Jan. 10, 2025. The CETROVO 1.0 subway car started its operation on the Qingdao Metro Line 1 on Friday.

With a carbon fiber composite body and frame, it is lighter and more energy-efficient than the traditional subway train. (Xinhua/Li Ziheng)

This photo taken on Jan. 10, 2025 shows a CETROVO 1.0 metro train before its operation in Qingdao, east China's Shandong Province. The CETROVO 1.0 subway car started its operation on the Qingdao Metro Line 1 on Friday.

With a carbon fiber composite body and frame, it is lighter and more energy-efficient than the traditional subway train. (Xinhua/Li Ziheng)

Passengers take a CETROVO 1.0 metro train on the Metro Line 1 in Qingdao, east China's Shandong Province, Jan. 10, 2025. The CETROVO 1.0 subway car started its operation on the Qingdao Metro Line 1 on Friday.

With a carbon fiber composite body and frame, it is lighter and more energy-efficient than the traditional subway train. (Xinhua/Li Ziheng)

Passengers take a CETROVO 1.0 metro train on the Metro Line 1 in Qingdao, east China's Shandong Province, Jan. 10, 2025. The CETROVO 1.0 subway car started its operation on the Qingdao Metro Line 1 on Friday.

With a carbon fiber composite body and frame, it is lighter and more energy-efficient than the traditional subway train. (Xinhua/Li Ziheng)

A driver is pictured at the driving cabin of a CETROVO 1.0 metro train before its operation in Qingdao, east China's Shandong Province, Jan. 10, 2025. The CETROVO 1.0 subway car started its operation on the Qingdao Metro Line 1 on Friday.

With a carbon fiber composite body and frame, it is lighter and more energy-efficient than the traditional subway train. (Xinhua/Li Ziheng)

A CETROVO 1.0 metro train leaves a parking lot before its operation in Qingdao, east China's Shandong Province, Jan. 10, 2025. The CETROVO 1.0 subway car started its operation on the Qingdao Metro Line 1 on Friday.

With a carbon fiber composite body and frame, it is lighter and more energy-efficient than the traditional subway train. (Xinhua/Li Ziheng)

This photo taken on Jan. 10, 2025 shows a CETROVO 1.0 metro train before its operation in Qingdao, east China's Shandong Province. The CETROVO 1.0 subway car started its operation on the Qingdao Metro Line 1 on Friday.

With a carbon fiber composite body and frame, it is lighter and more energy-efficient than the traditional subway train. (Xinhua/Li Ziheng)

This photo taken on Jan. 10, 2025 shows a CETROVO 1.0 metro train before its operation in Qingdao, east China's Shandong Province. The CETROVO 1.0 subway car started its operation on the Qingdao Metro Line 1 on Friday.

With a carbon fiber composite body and frame, it is lighter and more energy-efficient than the traditional subway train. (Xinhua/Li Ziheng)

A staff member introduces the CETROVO 1.0 metro train in Qingdao, east China's Shandong Province, Jan. 10, 2025. The CETROVO 1.0 subway car started its operation on the Qingdao Metro Line 1 on Friday.

With a carbon fiber composite body and frame, it is lighter and more energy-efficient than the traditional subway train. (Xinhua/Li Ziheng)