Passengers line up to ride Line 15 in Chongqing. (Photo/Chongqing Daily)
In the early 2000s, Chongqing was judged an unlikely city for a large rail network. Steep slopes, deep gullies, and karst caves make rail transit far more expensive here than on the plains. The city opened its first line only in 2005, when the country's first straddle-type monorail—the now-iconic Line 2 that runs through a building—began service.
Two decades later, Chongqing runs one of China's ten largest rail networks, and no mountain city in the world runs a bigger one: 15 lines, 358 stations and 500 km added since 2012. Passenger trips on the network have surpassed 13.5 billion, roughly ten per person in China.
Mountains and rivers split Chongqing into separate urban clusters. Metro and monorail lines now cross that terrain, linking the clusters to each other and to the center.
Line 15 is Chongqing's first urban express line and its first fully automated one. (Photo/Chongqing Daily)
Line 15, the newest, will connect three of them: the Western (Chongqing) Science City in the west, Lijia Smart Park in the center, and Longsheng New Town in the east.
Longsheng hosts advanced equipment and new-energy vehicle manufacturers, but its distance from the urban core has long made it harder to attract workers and new projects.
The opening of Line 15 is expected to improve access to the district, making it easier for businesses to attract workers and connect with the wider city. But extending rail services across Chongqing also means tackling some of China's most challenging urban terrain.
Getting a network of this scale through such terrain has required engineering solutions rarely needed in flatter cities. For example, Line 5's trains are designed to handle steep slopes and tight curves that standard metro systems cannot easily manage.
The challenges extend beyond the trains themselves to the construction of stations and tunnels. At Liziba, the station and the bridge carrying the track are separate structures, allowing the line to pass through a residential block rather than around it.
At Hongyancun, the station sits 116 meters underground, making it China's deepest metro station. Line 27 takes another approach, running beneath the Yangtze River. Its tunnel broke through in 2024, marking the first rail crossing beneath the river in its upper reaches.
Staff involved in the construction of Metro Line 15 take one of its first rides. (Photo/Chongqing Daily)
Chongqing has turned its hard-learned lessons into businesses. When Line 2 opened in 2005, the country had no monorail industry to speak of. The cars and the signaling came from Japan.
20 years on, Chongqing's core monorail equipment is made entirely at home, and more than 150 suppliers, from car bodies to signaling systems, produce about 10 billion yuan (1.5 billion U.S. dollars) a year. Mountain rail systems designed here now run in South Korea, Vietnam, and Mexico.
The difficult terrain and creative civil engineering have created a magical mix for tourists. At Liziba, visitors photograph the train that runs through a building. One stop away, crowds gather in blossom season for the same Line 2 train at Fotuguan station, the "train to spring."