Subway systems and similar are a great setting for a good deal of things, be it a frantic brawl, a stealthy escape, a shady investigation, or even just some realism, worldbuilding, and a means to get the PCs around town without anyone having bothered to buy a car.
The problem is, a great many places do not have anything remotely resembling a subway system, with the closest parallel being a city bus and/or taxis, if that. Whether the metro system is a mere occasional background for the campaign or the main setting, it's hard to make it convincingly as a GM if you have no experience with it.
I've been doing some research, and have enlisted the aid of friends who happen to LIVE in cities with very extensive metro systems, or close enough to have visited. I'll be sharing this resource and the fruits of my research for others who desire mass transport in their city, be it for a team of hard boiled detectives or explorers visiting a spaceport.
I'm going to try to make this a recurring thing, when I find topics for which information is not readily handy to the casual GM who wants realism without having to write a research paper.
"ok, so.. I'm not sure about the differences between Russian metro and NY subway, but I'll tell you what I know about the subway in regards to size.
Yes, the station does have to be as long as the train. Other than that, there's a huge range in size. The minimum would be something that's three tracks + two sidewalks wide. This accommodates trains going in both directions, a middle track for trains to skip stations (express or in case of construction), plus a standing platform on each side. The other floor would be for the turnstiles and booth, if there is a booth (there's always a booth on at least one "side" of the station, at one entrance. The station almost always has multiple entrances at the front and back of the train). An underground train may have the first floor at ground level or below ground level, with the train itself one floor below. An above ground train may have the first floor at ground level, or just have an open staircase from the street leading up to the first floor, with the train one floor above.
That's the minimum. One or two train lines may stop at a station like this, and there will be no other amenities. The next size up would have two to six lines, typically one to three local and one to three express, in any combination. This layout would be similar to the first, but almost always underground. It would basically have the following layout: local track - platform - express track - middle track - local track other direction - platform - middle track other direction. This layout may have a small news/candy stand in the middle or the platforms.
As it gets bigger from there, it also gets more complex, with trains on multiple layers, trains that are multiple city blocks from each other being connected through underground tunnels, etc.
Some stations have small shops such as small florists or accessory shops. Some stations are in the lowermost level of malls or department stores. Other stations house malls. The difference being whether you need to walk through a turnstile or not to get into the shop(s). The largest stations essentially look like airports, with food courts and somewhat larger stores inside, such as GameStops. Stores, except for the aforementioned news stands, are always on different levels from the actual train platform."