It'd be pretty cool if busses and trains were local-first.
replies(2):
Also, what do you mean by trains being local-first? Trains by definition need to share the same tracks with catastrophic consequences for getting it wrong. You can't figure out if a train is going to possibly be on the same route locally, or if your route has been obstructed. Somebody gets a schoolbus stuck on a crossing, it takes over a mile to stop a train.
In the days before systems existed for publishing such schedules and emergency alerts, should public transit service not have been attempted at all?
> Trains by definition need to share the same tracks with catastrophic consequences for getting it wrong.
Just because it uses the same rail gauge as intercity freight doesn't require it to run on the same set of tracks. But if it did, I assume "local-first" entails other traffic just being excluded when an emergency in the local system necessitates it.
Edit, for the pedantic: There's a huge difference between horizontal complexity (i.e. variety of transit options) and vertical complexity (complexity of a particular option). We have less horizontal complexity than we used to; but vertical complexity of a modern railroad is obscene compared to historical standards.
> But if it did, I assume "local-first" entails other traffic just being excluded when an emergency in the local system necessitates it.
No dice; as consider just 14 hours ago:
https://x.com/SFBARTalert/status/1963772853947355630?ref_src...
How does a local-first train safely operate if it could go through a police zone? You need communication, by definition, not local-first.
> Just because it uses the same rail gauge as intercity freight doesn't require it to run on the same set of tracks
Building a replica set of tracks that runs parallel to the current tracks just to avoid sharing doesn't strike me as a good use of anyone's time/money.
> "local-first" entails other traffic just being excluded
And how are you going to notify them that they are excluded when the network is down?
Wikipedia has a good survey [0].
I think our over reliance on the telecom network has lead to safety issues- mostly in terms of "what to do when the telecom goes down." Because on the whole, its astoundingly reliable.
The US congressional committee that recommended construction of the railroad was called the "Select Committee on the Pacific Railroad and Telegraph".
So it seems very early it was decided that no, rail transit systems should not be built without communications/publishing infrastructure.
[0] https://en.wikipedia.org/wiki/First_transcontinental_railroa...
BART has a non-standard rail gauge size that precludes it from interoperability with other rail networks.
We're talking about BART, which uses a track gauge of 5'6" instead of the standard US rail gauge of 4'8.5". They can't run on the same tracks.
(Actually, this is generally true even for those systems that do use 4'8.5" gauge track--I suspect that the standard US freight car envelope doesn't actually fit on most subway systems.)
That said there are other reasons a subway could end up being subject to Federal Railroad Administration[2] rules. I will note that I'm not an expert on those rules. But, generally passenger rail systems in the US are subject to Positive Train Control[3] or equivalent. It appears BART is actually one of the earliest adopters of Automatic Train Control[4], which appears to be a PTC equivalent. If not more automated.
[1] https://en.wikipedia.org/wiki/Loading_gauge
[2] https://en.wikipedia.org/wiki/Federal_Railroad_Administratio...
[3] https://en.wikipedia.org/wiki/Positive_train_control
[4] https://en.wikipedia.org/wiki/Bay_Area_Rapid_Transit#Automat...
Of course, centralized signaling is better, allowing for greater efficiency, helps dispatch keep track better track of the trains, makes handling malfunctioning signals a lot safer, among many other benefits. But it doesn't mean local signaling can't be done.
Modernization efforts focus on trains broadcasting position and speed so trains can travel closer together and still maintain a safe stopping distance, but that's again possible locally.
Operating switches is where it gets trickier. Some rail operators maintain the possibility to operate them locally, but that requires either stopping the train at each switch you want to change, or to deploy lots of people into the field to do it on schedule
https://www.nytimes.com/interactive/2025/04/20/nyregion/nyc-...
For me, this was the best picture:
https://static01.nytimes.com/newsgraphics/2025-03-10-subway-...
Someone has to stand at that machine 24 hours a day and push and pull levers to keep the trains from whacking one another.
As a related aside, the Chicago Transit Authority still ran freight on its tracks until not that long ago. Maybe the early 2000's?
It is certainly possible to send a freight train that will fit in most subway tunnels of the right gauge, but you may need a short locomotive and short cars.
(After all, what are the maintenance trains but a form of freight?)
I don’t know, but I would imagine, there’s still a block based setup as a failsafe backup in most or all modern rail systems.
But the point that you can do this local-first is still true. You will want to engage a couple bits of information with the neighboring block, but you don't need to know any global state, and if one block breaks down that only affects its direct neighbors
The standard US freight envelope probably counts as Plate C, which is 10'8" wide by 15'6" above the rail. Plate H is the standard for double-stacked containers, which pushes the height to 20'2".
(The part of the loading gauge that I'd be most concerned about is actually the width of the cars at the bottom of the carbody--passenger cars tend to be somewhat narrower than standard boxcar, and given a desire to minimize the platform gap, I'd think there's a decent chance that most freight would strike the platform.)
If air traffic control can fall back to pen and paper in a pinch, I think it would be cool IF trains had a decent fallback. ;-)
