Around Shashangou, between Dunhuang and the Altyn-Tagh-Qilian mountain system, the railway crosses the eastern edge of the Kumtag Desert. There was a concern that the megadunes characteristic of this area may shift, burying the railway. However, geological research indicated that the megadunes are mostly formed by solid subsoil, rather than just sand. Although there is still the issue of drifting sand, it is thought by the experts that the sand is mostly blown along the direction of the future railway rather than across it, and can be handled with certain precautions.