In wet climates, the soil beneath the road must be dramed. This is particularly important in fine-grained soils where the water can be sucked up near the surface by capillary attraction. Freezing of such soils is likely to swell them lifting the road and breaking its wearing surface. This breaking action is called frost heave. It can be avoided by laying subsoil drams across the road at least 1.3 m beneath the surface at intervals so that any water under the road is carried away from it either into pipes laid along the edges of the road or into ditches or natural open drains at a safe distance away from the road.