How a Subway System Matures a Metropolis

Metro systems and other mass transit infrastructure is critical for the maturation and success of modern metropolis. A city needs a way for the native population and visitors to move around in an orderly fashion. And for me buses are bare necessities, but it's the subway that makes the city come alive.

Subways don't just bring people from location to location, they also show where people are most likely to meet - either at or beyond the stations, or inside the metro car itself. It also shows the world the city is capable. London, New York, Tokyo all have world famous subway systems that are even part of the local folklore. Movies get made with these famous tracks part of the plot.

You can't just have any subway system though. Certain qualities must exist:

• obviously the subway needs to connect locations in the city that people want to go to: (tourist) attractions, trade centers, shopping malls, parks, airports and railway stations etc.
• transferring between subway lines needs to be seamless and clear.
• directions and signs should be in multiple languages, at least english and likely some mandarin chinese
• a payment system (a general mass transit card) that balances the need to cover the cost of the subway, with practical, first-time right logistics. You can't have travellers faff about with paper tickets that need to be checked by a human subway worker, or with complex payment systems that require you to go to three different offices.
• people need to be able to reverse course easily, without cost to them. The way metro stations and platforms are built, influences this ability.
• most importantly, subway stations and cars need to be safe and promote good behaviour.

The best I've seen:

1. Tokyo; Clean. Efficient. Always on time. Easily accessible. Clear directions (when you get the hang of it), which is not easy for a place where Hiragana is the norm. Unfortunately need several travel cards to use all the lines.
2. Shanghai; the Chinese seemingly built this subway up from scratch, and it shows. All the modern amenities have been thought about, train information is clear from flat-screen monitors, and it is dirt cheap to take a trip. A bit illogical though that sometimes you can't transfer without having to pay extra, and when you make a mistake and check in, you cannot check out immediately for free.
3. Seoul; user friendly payment system, sprawling network of stations. Transferring between lines is a trip in itself. Seems to take a long time to travel from point to point.
4. London; Practical. The oldest working metro system, but one that has clearly grown and matured over time. Amazing how basically every line is operated by a different company, yet to the traveler it is completely transparent. A bit cramped in places.
5. Montreal; esthetically one of the finest systems in the world, rivaling Moscow and Paris. Safe and effective, a clear reflection of the city's population.