Curbs are the circulation elements that make up the edge of where a raised sidewalk or a median meets a street or roadway. The main purpose of Curbs is to help delineate the edge of the pavement that separates the road from sidewalks and prevent drivers from possibly parking and driving on any sidewalks or lawns. Curbs also help promote structural support to the edge of a pavement and can help direct any runoff water from rain or melted snow into storm drains. Curbs are often categorized by shape, material, height, and whether the curb is combined with a gutter.