Where road construction layers (including any structural courses, foundations, kerbs or backing that provide edge support to road structures) extend below adjacent verges or unmade ground, any reinstatement must take account of such provisions. The reinstatement of such areas must match the existing layer thicknesses, with similar or equivalent materials.
Where there is no edge support, if an excavation comes within 600 mm of the edge of a road and the backfill extends below the intersection point shown in Figure S9.1, sub-base material must be used for backfill below that point. The intersection point is where a 45° line extending downwards from the edge of the road surface intersects the side of the trench nearest the road. Above this point, excavated material can be used as backfill.