The Moscow Metro is a state-owned enterprise. Its total length is 308.7 km (191.8 mi) and consists of 12 lines and 186 stations. The average daily passenger traffic is 6.6 million. Ridership is highest on weekdays (when the Metro carries over 7 million passengers per day) and lower on weekends. Each line is identified according to an alphanumeric index (usually consisting of a number), a name and a colour. Voice announcements refer to the lines by name. A male voice announces the next station when traveling towards the centre of the city, and a female voice when going away from it. On the circle line the clockwise direction has a male announcer for the stations, while the counter-clockwise direction has a female announcer. The lines are also assigned specific colours for maps and signs. Naming by colour is frequent in colloquial usage, except for the very similar shades of green assigned to the Kakhovskaya Line (route 11), the Zamoskvoretskaya Line (route 2), the Lyublinsko-Dmitrovskaya Line (route 10) and the Butovskaya Line (route L1).
The system operates in an enhanced spoke-hub distribution paradigm, with the majority of rail lines running radially from the centre of Moscow to the outlying areas. The Koltsevaya Line (route 5) forms a 20-kilometre (12 mi)long ring which enables passenger travel between these spokes. Signs showing the stations that can be reached in a given direction are in each station. A complete map is also on each station both inside and outside, and in the trains, but not on the platforms. Most of the stations and lines are underground, but some lines have at-grade and elevated sections. The Filyovskaya Line is notable for being the only line with most of its route at grade.
The Moscow Metro is open from about 5:30 am and until 1:00 am. The precise opening time varies at different stations according to the arrival of the first train, but all stations simultaneously close their entrances at 01:00 for maintenance. The minimum interval between trains is 90 seconds during the morning and evening rush hours.