| New Guanjiao Tunnel | |
| Line: | Qinghai–Tibet Railway |
| Location: | Guanjiao Mountain |
| Coordinates: | 37.1444°N 99.0831°W |
| Start: | 37.1828°N 99.1772°W |
| End: | 37.0092°N 98.8806°W |
| Startwork: | 2007 |
| Traffic: | train |
| Length: | 32645m (107,103feet) |
| Notrack: | two single |
| El: | electrified |
| Speed: | 160 km/h |
| Hielevation: | 3381m (11,093feet) |
| Lowelevation: | 3324m (10,906feet) |
New Guanjiao Tunnel [1] is a tunnel on the 2nd line of Qinghai–Tibet Railway in Guanjiao Mountain, Qinghai province. It is dual-bored, double-track rail tunnel. The total length of the tunnel is 32.645km (20.285miles), which made it at the time of completion the longest railway tunnel in China and fourth-longest in the world.
China Railway First Survey and Design Institute is responsible for the design. The New Guanjiao Tunnel was designed for two parallel single-track tunnels with speeds of up to 160kph. The total construction duration was projected to be 5 years. The tunnel was bored in difficult geological conditions and high altitude, exceeding 3300m (10,800feet) above sea level. The construction started in 2007 and was completed in April 2014.[2] The tunnel was opened on 28 December 2014.[3]
The tunnel's northeastern portal (37.1834°N 99.1778°W) is in Tianjun County, the southwestern portal (37.0094°N 98.8805°W) is in Ulan County.