Manhole covers, grates, and obstructions should not be located within the curb ramp, maneuvering area, landings or turning spaces. Where they must be located in the ramp or landing, they must be firm, stable, and slip resistant. Curb ramps should not be located where pedestrians must cross drainage structures such as inlets and manholes. Where a drainage grate must be located in the path of pedestrian travel, it must be ADA compliant with openings that prohibit passage of a sphere larger than ½ inch. In new construction, curb ramp design must consider both the location of the curb ramp and the drainage and utility structures. Additional drainage inlets should be located on the upstream side of all curb ramps where practical in order to avoid running water across the bottom of the ramp. Curb ramps must be located away from low points of the curb return. For more information on drainage design, see .