Where the trail crosses highways and waterways, many of the structures used to support the previous railway are either reused, or new prefabricated bridges have been placed on old bridge abutments. Roads that cross the Greenway fall in two general categories: Roads constructed while the railway or Greenway was in operation, which typically have the road on an even grade with the Greenway or (for larger highways) a bridge where one crosses the other; and roads constructed while the railway was abandoned, whose intersections may be difficult to cross because of differences in elevation between the roadway and the Greenway, sometimes accomplished via steep inclines or switchbacks.