Pedestrian and Railway

A pedestrian overpass allows pedestrians safe crossing over busy roads without impacting traffic.

Railway overpasses are used to replace level crossings (at-grade crossings) as a safer alternative. Using overpasses allows for unobstructed rail traffic to flow without conflicting with vehicular and pedestrian traffic. Rapid transit systems use complete grade separation of their rights of way to avoid traffic interference with frequent and reliable service.
Railroads also use balloon loops and flying junctions instead of flat junctions, as a way to reverse direction and to avoid trains conflicting with those on other tracks.

Examples of overpasses/flyovers

Overpasses near Mohakhali in Dhaka.  Overpasses near Barcelona  A high-capacity stack interchange: the Judge Harry Pregerson Interchange in Los Angeles  High Five Interchange five level stack interchange with multiple overpasses in Dallas, Texas  Sandgate Flyover, New South Wales, where two main railway lines pass over two dedicated coal lines  Flyover on Keelung Road in Taipei  Overpasses near Mohakhali in Dhaka.  New York State Thruway overpass  Pedestrian overpass, I-64, St. Louis, Missouri. This overpass is located at the St. Louis Science Center.