PURPOSE: To reduce displacement to load by forming a specified inclined grade in the direction of a kerb stepped section toward the downward direction of a lateral reinforcing rib mounted on the rear of a land slope by the lateral reinforcing rib.

CONSTITUTION: Auxiliary ribs drooped and formed on the rear side of an injection-molded land slope 1 consist of vertial reinforcing ribs 13 parallel in the direction of projecting width (a) and lateral reinforcing ribs 12 being crossed with the ribs 13 and parallel with the longitudinal direction (b), and the lateral ribs 12 form an inclined grade of approximately 6° in the direction of a kerb stepped section B toward lower sections. When such a land slope 1 is abutted and installed to the kerb stepped section B, the lateral auxiliary ribs 12 forming the inclined grade θ-2 of approximately 6° are directed at a right angle θ-3 in the direction that load such as a car is applied because the drainage grade θ-1 of a kerb A is approximately 6°, thus maximizing withstand load strength.