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Comment by marc__1 | Hacker News Reader

This is also an issue with subways. NYC subway, for example, originally had two different owners and they build their separate networks with different width so that one rail would not use the other. Today, they call it Division A and B trains.

[1] https://en.m.wikipedia.org/wiki/New_York_City_Subway_rolling....

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The US South had 5ft gauge during the civil war. There was a massive post-war effort to standardize the gauge that took place over a 36 hour period. All the southern railroads not already on standard gauge did so all at once from May 31-Jun 1 1886.

Tens of thousands of work crews pulled the pins of the west rail and moved it 3in inward. Simultaneously crews at rail yards modified the primary rolling stock.

Service resumed Jun 2 on standard gauge and for the first time passengers and freight could cross the boundary without a changeover stop.

It's a little more complicated in the case of the NYC Subway because the size of the tunnels and stations is based on the size of the rolling stock. BMT/IND (B Division aka the letter trains) trains simply can't be driven through IRT (A Division aka the number trains) tunnels. A "changeover" would entail widening tunnels and platforms many feet below Manhattan, not just moving a lot of rails.

Yeah that makes sense. I just thought it was really neat that the US pulled off such a massive project to standardize gauge over a single weekend - similar to Sweden switching from LHD to RHD on a single day. It's a huge coordination, organization, and training challenge. In the rail case it was done entirely on paper with a little bit of telegraph support.

To be maximally pedantic: the two divisions (IRT and BMT/IND) use the same rail gauge, but have different car widths, lengths, and weights.

(That may have been what you meant, but I think it’s an interesting distinction for those unaware!)

that's certainly interesting. i just heard about a case in germany where a city has two different systems, and they bought new trains for one of the systems but forgot that they had stations serving both systems where those new trains didn't fit because the other system had narrower trains and wider platforms. the new trains would scrape the platform edge and take damage.

> the new trains would scrape the platform edge and take damage.

The NYC subway, not to be bested, manages to do this even with the correct cars :-)[1]

[1]: https://www.reddit.com/r/nycrail/comments/i4airc/whats_the_t...

It was actually 3! The IRT is now the A division, and the BMT and IND are the B division.

I still do not understand how local rail ends up fragmented like this. The Tokyo metropolitan area has like… what? 8 operators? You’d feel like there would be some consolidation and yet.

In NYC, the MTA runs both so they are technically consolidated, but changing car widths on a live subway system that is used by millions of people every day is on the list of very difficult problems.

For example, if you wanted to conform the IRT lines in NYC (the numbered lines + the 42nd Street Shuttle) to the BMT/IND lines, you would need to (at minimum), update every platform (to back the edge away from the train), probably update every place two tracks are parallel and too close together, probably also update some of the routing and tunnels to enable a larger turning radius, and reapprove all of the tracks (including elevated portions) to support heavier trains.

Since all of the lines (barring the 7 and S) overlap at different points, you can't just make these mutually exclusive changes to one line at a time; you would have to shut down the whole system to make the changes, eliminating service to huge areas of the city for months (if not years).

Like any public utility, there's a huge cost to get the infrastructure in place because there is... well... a CITY in the way. The immense capital outlay is generally worth it for the first to enter the market in a given area, because they stand to collect 100% of the demand for the service they offer. In contrast, a second competing entity incurs the same capital outlay, but can only count on as much of it's competitors business as it can wrest away. Unless their offering is of substantially better value, the most they can realistically hope for is 50%. In cases like local rail service, the initial outlay is so immense that there's little chance that anyone could make a compelling business case for it.

See the earlier comment, the large Japanese private railways are real estate and hospitality companies with a train side business. Each has built their own little fiefdom, but they play nice enough (thru trains, tourist passes, and regional transit payment cars) to make all the effort not worthwhile.

Although during WWII and for some years after all the lines to the south and southwest of Tokyo were under Tokyu Railways (then known as Dai Tokyu, or "Big Tokyu).

They may appreciate that competition between the operators is a mechanism to support efficiency and progress in infrastructure. Each rail operator wants people visiting their malls, building near their stations, and in working towards that, they improve their systems.

If I'm not mistaken, London also has two different types of tube trains, although in that case I don't think it'd because of different owners, but one is simply narrower and therefore cheaper to make tunnels for.

Actually it's both of those, and more complex: multiple private companies building at different times in history, using widely diverse tunnelling techniques and depths to suit different needs.

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

The London sub-surface and deep-level tubes were made by different technologies. Surface by cut-and-cover and deep-level by tunnelling shield. Both were the first of their kind, and deep-level wasn't possible until electric propulsion was invented. The deep-level tunnels are narrow because of the expense of digging by hand.

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