A Brutal Road to the Edge of the Sky: Shiquanhe Observatory and AliCPT

Located near Shiquanhe town, in the Ngari (Ali) Prefecture of the western Tibet Autonomous Region in China, the road to the Shiquanhe (Ali) Observatory and the Ali CMB Polarization Telescope (AliCPT) is a high-altitude concrete route built to provide access to these scientific facilities.

Shiquanhe Observatory and AliCPT

How long is the road?

The road starts from China National Highway 219 (G219) near Sha Zi La and climbs approximately 15.1 km (9.38 miles), reaching a maximum altitude of 5,403 meters (17,726 ft) above sea level. The route is steep, with numerous hairpin turns and long exposed sections. While mostly paved and wide enough for maintenance vehicles, a 4×4 vehicle is recommended due to its steepness. Careful driving and awareness of severe weather hazards, including avalanches, snow, landslides, and icy patches, are required.

Why was the road constructed?

At the summit, the Shiquanhe Observatory sits at about 5,100 meters (16,700 ft), while the nearby AliCPT B1 site is located around 5,176 meters (16,981 ft). These elevations were chosen for optimal observing conditions: very low precipitable water vapor (median PWV ~2.5 mm), good median seeing (~0.8 arcseconds), and a high fraction of photometric nights (~57%), making the site ideal for both optical and microwave observations.

Why is the road used?

The road serves to transport personnel, equipment, and supplies to support observatory operations. Travelers should plan carefully for altitude and limited services along the route, and prepare for rapidly changing weather. Proper preparation is essential for safety and a successful journey to one of the world’s highest scientific facilities.

Extra advice

  • Acclimatization: Spend a day or two in Shiquanhe town (~4,300 m) before ascending.
  • Supplies: Bring extra fuel, food, water, and emergency equipment; services along the road are minimal.
  • Weather: Avoid travel in snow, heavy rain, or high winds. Conditions can change rapidly.
  • Vehicle: A reliable 4×4 with good brakes and tires is essential.
  • Communication: Mobile coverage is limited; consider satellite or radio devices for emergencies.

Pic: Zg M

 

 

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