In road building, "ballast" refers to a layer of material placed underneath the tracks or pavement to provide stability and drainage. Typically made up of coarse stones, gravel, or crushed rock, ballast ensures that the road structure is well-supported and remains level. It helps to distribute the load from the traffic above, preventing the road from sinking or shifting. Additionally, the gaps between the stones allow for effective drainage, preventing water accumulation and potential damage to the road foundation.
