Tokyo's metro region is smaller than Paris and fits more than 3 times the people. The metro's top speed is up to 5 times as fast as Paris's metro. It's on a completely different scale. And given that Paris is Europe's second busiest metro system it tells you something.

It is unfortunately a bit hard to compare the length of the system, since it's hard to distinguish between the local lines that are not operated by tokyo metro vs. the longer distance ones.

Overall, your post is thoughtful.

Can you help me to understand this part?

    The metro's top speed is up to 5 times as fast as Paris's metro.

I would not call the Tokyo subways lines (both companies) very fast when riding a local train. I went to Paris for a week and found the metro lines fairly similar.

You are correct, taking the reference speed as measurement is not a valid line of reasoning.

The average speed is higher, the speed is lower the closer the stations are together, but the speed also depends on the line; i.e. the Ginza line added ATS(automated train stop, added in 1993). I just learned that Paris' Line 14, that went into service in 2022, also drives at accelerated speeds, it's the first line with ATS in Paris. I think the main problems that need to be addressed with respect to higher speed transportation are the following:

1. the breaking system needs to be assisted (ATS)

2. the railway needs to be replaced and reinforced

3. turn angles can't exceed a certain degree

1 and 3 are a design issue that isn't really addressed in older metro system, and 2 is probably a political problem. Contrary to my previous belief it seems that France is at least trying to address some of the points in their metro extensions, which is nice.

The tokyo metro is much cleaner and does not smell like piss, has none of the homeless population living in and you can be safe in day and night. Only a blind person with a blocked nose could pretend its about the same.

Tokyo metro has its drawbacks as well, namely, I found the stations rather difficult to navigate for foreigners. Of course this being Japan there are many nice people eager to help everywhere, but (again of course) they don’t speak english.

Tokyo has signs in English everywhere. It is difficult to navigate the first time you are looking for a connection but after a few days you get used to how things work and how to find your way. There are also tons of apps you can use to help you.

In Tokyo it's simple for a foreigner, open Google Maps, enter your destination, the app gives you the number where you have to go, you take your train, and that's it.

No different than any other cities.

Last time I was there Google Maps weren't good at navigating through the stations. And the signs at the stations were difficult to follow compared to other metro systems I'm used to.

I'm sure everyone is able to figure it out, but IMO they could take some inspiration from e.g. London or Paris.

One tiny thing they could do to improve metro stations: Put big stickers on the floor that guide you to an interchange or an exit. Most stuff in Tokyo is "up" (overhead signs), but they could also use "down" to improve things. I was recently traveling on the metro in Kunming (Yunan Province, China), and I noticed they use the "down" part very well to guide you -- with Chinese and English. It was very helpful in more complex stations.

One more idea: Tokyo metro stations don't make a lot of use of colour schemes. I have used some metros that use very loud colour schemes all throughout the station to guide you to interchanges. Again: Very helpful for visitors.

It also helps to learn the Katakana alphabet, which is easy enough for any computer nerd that one can do it on the plane to Tokyo. You can then sound out the syllables on signs and know that アキハバラ sounds like "Akihabara" and thus you're on the right train.

https://en.m.wikipedia.org/wiki/Katakana

You just need to learn that there are multiple metros and some JR trains, and then it will become easy to understand. Modern metro apps and maps can calculate the path using all of those without any problem.

I remember finding it very busy, but we’ll organise - helps that most signs are bilingual. And the station staff are really helpful if you look lost. The hardest part was the ticket machines but that’s common all over I find.

I really don't remember most signs being bilingual.

What year did you ride the Tokyo metro? Jesus, on most lines there are four languages -- Japanese, English, Korean, Chinese. And, the newest ticket machines have many, many more languages -- even Thai!