Moscow Metro is the seventh largest metro system in the world according to the length of its operation route, and the fourth busiest metro system in the world and the first busiest metro system outside Asia in terms of annual passenger flow. Nowadays, the layout of Moscow Metro is consistent with that of the ground, showing radiation and circular lines. There are 12 lines, including 11 radiation lines and 1 circular line. The total length is 312.9 kilometers. There are 171 platforms. 4000 metro trains run on the metro line with more than 5000 carriages.