Rails and sleepers are visible. The stone under them does the quiet work: it holds gauge, drains the formation and can be restored after traffic. Shortage of specified ballast has been a real constraint on Iranian railway work.
Supply
A mine next to a station can load by road or rail. That is the point of Nangerd: the product is made beside the line that uses it.
Think in a system
Track performance is a system property. A strong ballast cannot compensate for a weak formation, blocked shoulder drains or an incompatible sub-ballast. Design reviews should connect laboratory values to layer thickness, groundwater, axle load, speed and the maintenance access available on the route.
Logistics is engineering
Because aggregate is heavy, the delivered cost and carbon footprint are governed by distance, loading mode and return movements. A rail-connected source can reduce truck kilometres and keep a renewal possession supplied at a predictable rate.
