A bridge carries a road or railway across a river, a valley or another obstacle. The simplest bridge is a beam supported at each end by pillars. Beam bridges cannot stretch across wide gaps, so other kinds must be used, such as arch bridges and suspensuion bridges. Bullet Train A bullet train is a high-speed train that is shaped rather like a bullet.
Bullet trains are streamlined so that they can travel faster.
Gauge Distance between the inner running faces of two rails on the same track. It transports them over short distances in a short time. Mass transit systems are used in cities, where the roads often become blocked with traffic. A mass transit system may include buses, trams, an underground railway and a surface railway. The slower line in a multiple track area.