Breakthrough for Yan’an-Yulin high-speed rail as Huangjiayuan Tunnel breaks through

According to China Railway Group Limited, Huangjiayuan Tunnel on the Yan’an to Yulin high-speed railway was broken through on 24 October. It marks the first tunnel exceeding 10 kilometres to be completed along the whole route.

The single-bore, double-track tunnel sits in Qingjian County, Yulin City, and stretches for 10,381 metres. Its route cuts through complex geological formations, dominated by horizontal sandstone and shale strata alongside sandy loam. The surrounding rock along the alignment is heavily fractured with low self-stabilising capacity, and the tunnel passes through four shallow sandy loam sections, with rock cover reducing to a minimum of just 11 metres. Multiple geological hazards overlapped throughout the construction phase.

The project team adopted full-process mechanised tunnelling, deploying a suite of specialised and intelligent plant including three-boom rock drills, wet spraying manipulators, arch installation machines and integrated drilling, anchoring and grouting units. Nine automated working lines were established, while a digital management platform for drill-and-blast tunnel construction supported the integrated mechanised workflow. The finished breakthrough came 92 days ahead of the scheduled construction timetable.

The Yan’an‑Yulin high-speed railway runs across northern Shaanxi, with a total length of 238.7 kilometres and a design speed of 350 kilometres per hour. It forms a key segment of the Baotou‑Yinchuan‑Hainan corridor within China’s national eight vertical and eight horizontal high-speed rail network. Once fully opened, the journey between Yan’an and Yulin will take roughly one hour by train, while the fastest rail trip from Xi’an to Yulin will fall to around two hours. The completed line will support high-quality economic and social progress across the region.