A high-speed rail line crossing the mountainous central China region has opened to traffic, according to state news agency Xinhua.

The opening marks another addition to what is already the world's largest high-speed network. Mountain crossings remain the most expensive category of rail construction in China, typically requiring extensive tunnelling and viaducts, and each new line through such terrain extends the network into provinces where conventional rail journey times have long constrained passenger movement.

Xinhua's report confirms the line's opening but the announcement, as carried, gives no timetable, station list, speed rating or construction cost. National operator China State Railway Group generally publishes detailed operating plans — train frequencies, end-to-end journey times and fare structures — around each route opening, and those figures will determine the line's effect on competing air and road services in the affected corridors.

China's high-speed network now exceeds 45,000 route-km, and the central mountainous belt, spanning provinces such as Guizhou, Chongqing, Hubei and Hunan, has been a focus of recent construction because of its role linking the developed eastern seaboard with the southwest and western regions.

Further operating details, passenger capacity figures and the line's position within the national eight-vertical, eight-horizontal grid are expected as the operator releases the full service pattern.

Watch for the first-month ridership data, which will show whether the new mountain route is drawing traffic at rates comparable with other recent openings in the region.