Rapid transit or mass rapid transit (MRT), also known as heavy rail, metro, subway, tube, U-Bahn, T-Bane, metropolitana or underground, is a type of high-capacity public transport generally found in urban areas. Unlike buses or trams, rapid transit systems are electric railways that operate on an exclusive right-of-way, which cannot be accessed by pedestrians or other vehicles of any sort, and which is often grade-separated in tunnels or on elevated railways.
