Placing a Road Centerline element in the map simulates a continuous swath of impervious surface. Selecting Road Centerline as the Type for a 2D Polyline, enables the option to provide a Width. A Road Centerline is similarly modeled as a Road Area in applying adjustments to the underlying 2D grid. The nominal width of the Road Centerline is extruded about the center of the polyline, yielding a polygon shape. As such, the calculation option Polygon Intersection Type governs the subset of 2D grid cells that will be refined by the centerline element. In contrast to a Breakline, a Road Centerline allows for nominal and relative elevation adjustments. Similar to its Road (2D Polygon) counterpart, a Road Centerline supports adjustments to the hydrologic parameters of the 2D grid.