Workers carry out renovation work on the contact wire system along the Lanzhou-Lianyungang Railway at the Wolongsi Station in Baoji, northwest China's Shaanxi province, Sept. 10, 2025. (Photo/Liu Yijiang)

In 1975, deep in the Qinling Mountains, China's first fully electrified railway, the Baoji-Chengdu Railway, marked the beginning of a transformative journey toward railway modernization.

Half a century later, on the Chengdu Plain, engineers are developing a cutting-edge 400 km/h traction power supply system for the CR450 bullet train, which is expected to establish a new global benchmark in high-speed rail operations.

From humble beginnings to a globally leading network, electrification has played a pivotal role in China's railway evolution, from conventional lines to high-speed rail, and from traditional operations to digital systems. By the end of 2024, China's operational railway network had reached 162,000 kilometers, with more than 120,000 kilometers, or 75.8 percent electrified.

Electrified railways rely on electric traction power, with high-speed rail among their most advanced forms. The core components - power supply systems, traction, communications, and signaling - form the technical backbone of the electrified network.

Technicians inspect a bullet train at a maintenance facility in Zhengzhou, central China's Henan province. (Photo/Wang Wei)

Compared to diesel-powered lines, electrified railways offer superior performance. In freight transport, China's heavy-haul electrified railways can handle 5,000 tons with a single locomotive, while the Datong-Qinhuangdao Railway has normalized operations with trains weighing up to 20,000 tons. In passenger services, a 16-car high-speed train carries approximately 900 tons.

Speed is another transformative aspect. When the Baoji-Chengdu line was non-electrified, trains ran at only 20 to 25 km/h. Today, Fuxing CR400 bullet trains can reach a commercial speed of 350 km/h. Electrification also delivers significant environmental benefits: electric trains emit no exhaust, generate lower noise, and contribute substantially less air pollution than diesel alternatives.

China now boasts the world's largest electrified railway network, operating across diverse and challenging environments - from frigid winters to scorching summers, and from humid lowlands to high-altitude plateaus. These experiences have positioned China as a global leader in railway electrification and high-speed rail technology.

While some might reduce electrification to "poles and wires," the underlying engineering is highly complex. Overhead contact wires are often called the "lifeline" of high-speed trains. These wires must withstand extreme demands in terms of strength, conductivity, heat resistance, and durability.

"In the early days, we used copper-magnesium and copper-tin wires," explained Zhang Jian, chief engineer at China Railway Self-creation Electric Co., Ltd. "But they couldn't fully support the requirements of 350 km/h or higher speeds, prompting urgent innovation."

After three years of research and development, Chinese engineers became the first in the world to industrialize high-strength, high-conductivity copper-chromium-zirconium alloy wires. These new wires improve conductivity by 20 percent and support safe, stable, and cost-effective operations at 400 km/h, filling a crucial gap in global rail technology.

A bullet train passes through Cailing township, Duchang county, east China's Jiangxi province. (Photo by Liu Xun)

As the world's busiest high-speed rail network, China faces ongoing challenges such as overhead line wear. Traditionally, defect detection involved capturing millions of inspection images and manual review by experienced engineers.

"The workload was immense," said Zhang Zhongyi, general manager of the Beijing-Shanghai high-speed railway maintenance company. "Our team had to manually analyze over 14 million images annually."

To address this, China developed a visual intelligence system for high-speed railways in 2019, using AI to pre-screen and detect over 1,300 types of potential defects before human verification. The system has significantly enhanced detection accuracy and efficiency.

Leveraging technologies such as big data, 5G, cloud computing, drones, image recognition, and intelligent equipment, China has built a smart maintenance platform that has cut traction power maintenance costs by 20 percent, extended overhaul intervals by 20 percent, and increased the service life of components by 20 percent.

From the Lhasa-Nyingchi Railway, the highest electrified railway in the world, to the Datong-Qinhuangdao Railway, which has transported over 9 billion tons of freight, and to the newly opened Chongqing East-Qianjiang section of the Chongqing-Xiamen high-speed railway with a designed speed of 350 km/h, China's electrification journey exemplifies the nation's transition from "made in China" to "smartly manufactured in China." It continues to drive economic growth, social development, and the broader process of Chinese modernization.