The sanding system is used to increase the frictional force by blasting sand between the rail and the wheel in rolling stock.
The railway vehicle consumes the sand for eliminating weak friction between the wheel and rail while it's running on the rail. Daily or weekly this lost sand must be refilled.
In railway vehicles, undesirable friction (negative friction) between the rail and the wheel body is the main contributor to high maintenance costs, noise and environmental pollution, fuel consumption, and potential derailments.