The subway, also known as the urban railway in Vietnam (English: Rapid traisit, Mass rapid transit (MRT), heavy rail, metro, subway, tube, U-Bahn, underground) is a large transportation system. large used to carry passengers in an urban area, often running on rails. These routes can be placed underground, or overhead by a system of viaducts. Unlike tramway, subway can reach high speed because it has its own way, not sharing the road with other means of transportation. On certain routes, large numbers of passengers can be transported. Since there are so many trips, train travel is more convenient and comfortable for passengers. Most major cities in the world have subway systems. Same model as tramway and bus, metro has fixed stations to stop for guests to get on and off, but because of its own way, the subway goes faster, without traffic jams and also safe Britain was the first country in the world to build a subway line, the first one being just 6 kilometers long.