A roadway or other transport corridor infiltration system which collects runoff while allowing for the easily removal of litter from its surface. The infiltration system comprises at least the edge surface of the roadway or other transport corridor being formed by a plastics grid structure having at least its upper surface formed by an array of alternate openings and support members, such that water can permeate therethrough. An infiltration layer is located at least below and in communication with said grid structure, filled with aggregate material, which is larger in cross-section than the width of the openings of said grid structure. A geotextile wrapped water permeable infiltration tank located below and in communication with said infiltration layer, such that runoff passes through the grid structure into the infiltration layer and into the permeable infiltration tank, where the water is stored and/or flows back into the soil through the walls of the tank and the geotextile.