They aren't in Japan. Why would they be anywhere else?

Many subway-trains in Japan are trains for the first 20 stations, then "subways" for the next 10, then trains for the 20 stations after that. Same cars. They may have been 3 separate lines at one time but they got connected.

In the US, outside of a few special cases, if you're operating on the national rail network, you're operating on rail owned by a freight company, and they have priority. Amtrak often struggles to operate more than 1 or 2 trains an hour as "guests" on these routes. This is very UNLIKE Japan where the freights run on almost a totally different set of tracks.

Also, from a regulatory standpoint, freight and intercity railways (e.g. not subway/light rail/metro/trams) are subject to full FRA regulations, compliance with which would add even more costs, for little real benefit at the speeds they travel at.

Plus, in practice subway/light rail is electrified, and anything else (again with few caveats) is not. In towns with both it is very rare for them to use the same stations.

Rail freight and passengers mostly share the same tracks in Japan with the exception of the Shinkansen network* which is passenger only. The big difference is Japan sends way less freight by rail than the US and freight that does go by rail is scheduled at night when there are no passenger trains running.

*There’s probably an exception to the exception for the Akita / Yamagata branches that partially run on regular train lines.

On the one hand having passengers go by rail is not good for carbon. On the other hand replacing freight rail with trucks is also not good for carbon.

There are few rail networks that manage to serve both well.

Subways can be non-rail, as seen with the Montreal subway, but subways are usually a type of rail transit. Also, once you read the article, you'll see that the author is referring to subways.

>Subways can be non-rail, as seen with the Montreal subway

Yes, and it's terrible. The Montreal subway is by far the noisiest subway system I've ever used. Even standing on the platform is a terrible experience because it's so loud when the cars are moving.

How does the noise compare to the tube in London?

From my experience living in London, the tube is worse (at least the deep level lines which are much louder) but somewhat comparable to Montreal.

Both seem to come in around 80dBA average, but some of the tube lines peak at 90 or 100+dBA.

Sorry, I've never been there so I can't comment. But I thought London's system was a rail system; if that's the case, it should naturally be quieter.

London's system is very old so basically it's loud because it's built with much tighter curves than a modern system would be built with today, plus there are few platform doors isolating noise away from people on the oldest lines.

Oh, I see. That sounds like the Oedo line here in Tokyo: it has several very tight curves, so it's extremely loud inside when the train goes around those curves.

But that's not really what I'm talking about with Montreal: in Montreal, the subway system is loud for the people standing inside the station. (The trains are noisy inside too, but that's just in addition.) Every time a train enters or leaves the station, it's deafeningly loud, because of the rubber ties. You'd think it shouldn't be this way (after all, cars have rubber tires and are very quiet at low speeds; it's only at freeway speeds that rubber tires get loud on cars and trucks), but it is. It seems to be caused by the trackways: the tires are constantly rubbing on the sides of the track, so the cars are very noisy any time they're in motion, and it's really miserable just standing on the platform.