About 40% of the subway system runs on surface or elevated tracks, including steel or cast iron elevated structures, concrete viaducts, embankments, open cuts and surface routes. , there are of elevated tracks. All of these construction methods are completely grade-separated from road and pedestrian crossings, and most crossings of two subway tracks are grade-separated with flying junctions. The sole exceptions of at-grade junctions of two lines in regular service are the 142nd Street and Myrtle Avenue junctions, whose tracks intersect at the same level, as well as the same-direction pairs of tracks on the IRT Eastern Parkway Line at Rogers Junction.