People visit the China International Metro Transit Exhibition in Qingdao, east China's Shandong Province, on Sept. 18, 2025. The exhibition was held in the West Coast New Area of Qingdao on Thursday, setting up exhibition areas such as vehicle system and equipment supply chain, signal communication system, IT technology, and artificial intelligence. (Xinhua/Li Ziheng)

People visit the China International Metro Transit Exhibition in Qingdao, east China's Shandong Province, on Sept. 18, 2025. The exhibition was held in the West Coast New Area of Qingdao on Thursday, setting up exhibition areas such as vehicle system and equipment supply chain, signal communication system, IT technology, and artificial intelligence. (Xinhua/Li Ziheng)

People visit the China International Metro Transit Exhibition in Qingdao, east China's Shandong Province, on Sept. 18, 2025. The exhibition was held in the West Coast New Area of Qingdao on Thursday, setting up exhibition areas such as vehicle system and equipment supply chain, signal communication system, IT technology, and artificial intelligence. (Xinhua/Li Ziheng)

People visit the China International Metro Transit Exhibition in Qingdao, east China's Shandong Province, on Sept. 18, 2025. The exhibition was held in the West Coast New Area of Qingdao on Thursday, setting up exhibition areas such as vehicle system and equipment supply chain, signal communication system, IT technology, and artificial intelligence. (Xinhua/Li Ziheng)

A visitor takes photos of a model of a hydrogen-powered train at the China International Metro Transit Exhibition in Qingdao, east China's Shandong Province, on Sept. 18, 2025. The exhibition was held in the West Coast New Area of Qingdao on Thursday, setting up exhibition areas such as vehicle system and equipment supply chain, signal communication system, IT technology, and artificial intelligence. (Xinhua/Li Ziheng)

People visit the China International Metro Transit Exhibition in Qingdao, east China's Shandong Province, on Sept. 18, 2025. The exhibition was held in the West Coast New Area of Qingdao on Thursday, setting up exhibition areas such as vehicle system and equipment supply chain, signal communication system, IT technology, and artificial intelligence. (Xinhua/Li Ziheng)

People visit the China International Metro Transit Exhibition in Qingdao, east China's Shandong Province, on Sept. 18, 2025. The exhibition was held in the West Coast New Area of Qingdao on Thursday, setting up exhibition areas such as vehicle system and equipment supply chain, signal communication system, IT technology, and artificial intelligence. (Xinhua/Li Ziheng)