The edges are what get people: the strip along a storefront, the ramp at the curb, the two feet of walk beside a parked car. Clean Perimeters LLC works those edges through Charleston, Rossville and Woodrow — plowing lots and drives, shoveling sidewalks, entrances, steps and hydrant cuts, salting the corners a plow blade can never quite reach. A lot can look plowed and still be treacherous at its border, which is exactly why the trucks carry shovels and spreaders alongside the blade. On a clear cold morning near the Outerbridge you can see steam lifting off the wet asphalt where the salt has done its work. Nothing left to catch a heel.