Why do passengers on a Chinese train wash themselves Windows in train cars before the trip

In China, there's a train where passengers wash their own windows before departure. The reason is the incredible views outside the window during the journey.

Routes Z1164 and Z165 run from Shanghai to Lhasa, the capital of China's Tibet Autonomous Region. A significant portion of the journey (from Qinghai Province to Lhasa) is considered one of the most scenic and high-altitude train routes in the world—the train passes through plateaus, emerald lakes, and mountains. To ensure even the smallest speck of dirt doesn't obscure the view, passengers polish the windows themselves until they're spotless.

The train from Shanghai covers 4,300 km, and the journey takes approximately 45 hours. Sleeper berths start at 700 yuan. On the second day of the journey, passengers are provided with oxygen, as the train ascends to altitudes of over 4,000 meters. The highest point on the route is the Tang La Pass, at approximately 5,068 meters above sea level.