Metros around the world

Obviously it depends on how you define "metro" as to what would be included but I think I've been on the following systems.

London, Tyne and Wear, Glasgow, Liverpool, Paris, Lyon, Lille, Lausanne, Brussels, Charleroi, Oslo, Berlin, Munich, Vienna, Wuppertal, Budapest, Koln, Sydney (more like Crossrail really), Milan, New York, San Francisco, Toronto, Istanbul, Hong Kong, Singapore, Amsterdam, Rotterdam, Den Haag (Randstad Rail), Tokyo (both subway systems plus other rail services run in tunnel), Yokohama.

There are a number of european countries I've never visited, eg Spain, so I've got lots of Metro catching up to do.

All networks have their quirks and traits. Hard to say if I have a favourite system although I've always been impressed with the high reliability and efficiency in the Far East systems.

Tyne and Wear pretty much feels like the early DLR, in that a lot of it was quickly and cheaply built from kits, so all the stations look the same, especially the "awnings" on the underground sections, which are the same used on lots of the overground sections (except Haymarket, that got re-built by a local private consortium and looks much more like a tube station). The big problem is that the refurbishment of the Metrocars was not good enough and they basically fixed them up cosmetically, but didn't deal with the ageing traction packages, which means the service has gone right down the pan.

The New York subway is very......functional. It certainly doesn't have the same feeling of safety that the London Underground gives you. All the stations are dark and grotty, even the above-ground ones, which seem to have the minimum amount of work done to them.

The Paris Metro varies wildly depending on the line you're on. The more "touristy" the line (1 and 14 especially) the nicer it is. Some of the RER is nice, some of it is just cut and cover concrete slabs.

The Rome metro is generally nice although has a lot of graffiti.

Merseyrail's an S-Bahn really, but pretty good, decent frequencies on Sundays too. The 508s are being run into the ground though, although the refurbishment is pretty decent.

Hamburg's S and U-Bahns are fantastic, good frequency, generally nice stations.

Lyon has all kinds of different things, from Funicular railways with an actual service, to tyred metros, to trams, to tram-trains, but all integrated and generally pretty modern in appearance and feel. 

Then you're looking at Stadtbahns which I guess are "Metros" rather than "Trams" but very much bridge that gap. Cologne and Stuttgart were both pretty nice, but they end up very busy, because they have to deal with Metro-style capacity.

The only unusual one is Cairo.

It's unusual in that it's the only one I've been on that no one else had already mentioned.

Sorry, I was rather unclear.

To pick two metro systems from many that I have been on. In 1985 I helped guide over 100 young adults from Europe, Africa and India through New York in the morning rush hour in order to catch a coach. At that time, I was a young adult. The journey involved a change of subway line and I am proud to say that we lost nobody. In 1986 I travelled on most of the East Berlin U-bahn system, and some of the East Berlin S-bahn, including one stretch that transversed the Berlin Wall border area.

One metro system that got away was that I didn't manage to travel under East Berlin on a West Berlin U-bahn line, so I never experienced the ghost stations.

Considering it is such a young system, the Warsaw Metro has a good assortment of stock from Alstom and Siemens to Metrowagonmash. The Russian built Metrowagonmash 81-717.3 have exceptional motor sounds, rattles and more!

Some of the stations on the recently opened M2 line are also quite stunning.

No-one has mentioned Boston. Three metro style lines, which are really showing age. Also the strange Green Line, using trams with a strange underground section, street running, and some of the outer sections like a traditional railway.

Perhaps I should have used 'singular' like Sherlock Holmes (Jeremy Brett version).

Absolutely not sir, you must retain American idiomatic speech when referring to American rail systems   Strange is good.  

In the past few years I have visited Chicago, Berlin (fascinating system - a must-see at Wittenbergplatz station is the London Underground roundel sign, given to them by LT),Vienna, Frankfurt, Brussels and Paris. Hamburg is next in May.

Platform Train Interface i.e. where people getting on and off the train

Except its not a door, people fall down the gap between the train and the platform (part of the PTI) not the gap in the door.

When the train isn't there its just the platform, when passengers are going between the two in either direction its the PTI.

No, PTI (as the name suggests) refers to the whole interface between the train and platform and encompasses the physical aspects (size, shape) as well as the interaction of people and objects with the interface. Getting on and off a train is by far the most common way of interacting with the PTI but it is not the only one - falling between train and platform (whether or not attempting to alight or board), leaning against the train, dropping something in the gap, getting hit by a train while standing on a platform, etc. are all interactions with the PTI.

The term might be modern, but the thing has existed as long as trains have called at platforms and it is far from nonsense.