This application containing the best collection of Metro Sounds for android devices. sounds have been selected very carefully to be a good and fun user experience, we hope you will enjoy using the app and listening to Metro Sounds. Rapid transit, also known as heavy rail, metro, subway, tube, 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.