Tokyo Metro
Tokyo Metro

Sometimes ‘metro’ is used to describe a single rail line, sometimes a ticketing authority, sometimes a train operator, sometimes a city’s entire rail system, sometimes just an inner city rail network…and so it goes.

I’m interested in its use as a description of a particular type of public transport system, something along the lines of what Nick Mead at Guardian Cities describes in this definition: (1)

I’ve defined “metro” as high-capacity urban heavy rail systems that run on grade-separated right-of-ways. They run with short headways, at least at rush hour, and are generally built to serve commuters.

This definition from the Free Dictionary says a metro is:

An underground, or largely underground, railway system in certain cities, esp in Europe, such as that in Paris.

There’s probably no correct answer, however here’s what I’d suggest are the key characteristics of a metro:

  • A high density of lines and stations forming a ‘grid’ pattern – there’s a station within a reasonable walk of virtually any origin or destination within the area of service.
  • A large number of interchange stations at key ‘grid’ nodes – they provide connectedness by enabling travellers to transfer between lines.
  • Very high frequencies – between 2 and 4 minutes during the day. Short headways maximise capacity and minimise waiting times.
  • High capacity carriages – The emphasis is on standing rather than sitting. Wide doors allow quick loading and unloading.
  • High speed – trains run in their own grade-separated right-of-way. Each line has a dedicated set of tracks from end to end.
  • Long hours of operation – the metro is used for all trip purposes, not just commutes.

Networks with these characteristics are generally found in small areas with a high population density, usually the inner city. They’re not luxuries; they’re necessary in these locations to move people on a grand scale.

For example, the Paris Metro only covers the 90 sq km of central Paris (circa 5 km radius). That’s about 5% of the total urbanised area. It’s very dense though, accounting for 20% of the metropolitan population, plus tourists (France gets more visitors than any other country in the world).

The high density helps by making trip distances short. It also discourages car use; other than in the dead of night, driving is the slower option in places like central Paris.

Metros typically use trains because of the high capacity they offer but in some circumstances other modes might make more sense; the key requirement is that vehicles have their own right-of-way. They don’t need to be underground either, but if they’re on the surface they must be grade-separated or have priority at intersections.

Subways or elevated structures are often the only available or acceptable way of achieving these attributes in established areas.

Australian cities can learn a lot from metros elsewhere but they’re not like Paris, Barcelona or London. They’re much less dense, car use is easier, and our rail systems are geared to delivering distant suburban commuters to a geographically tiny CBD.

We need a local transport solution. As I noted recently, the public transport component is likely to involve coordinating an improved train system with a dense ‘grid’ of high frequency bus/tram routes operating in dedicated road space. They’ll need priority (or grade separation) at intersections too.

The big challenge will be winning road space and road priority away from cars.


  1. Nick Mead uses this definition in his quiz on ‘naked’ metro maps. I got 9 out of 11; pretty good but not brilliant.