A computer upgrade shut down BART

It'd be pretty cool if busses and trains were local-first.

If you can't send updated schedules or emergency alerts through the system, I also don't want service started. It doesn't have to be an individualized problem to render local-first useless.

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.

Trains traditionally operate on signalling blocks: a section between two signals is a block, a block is occupied if any part of a train is inside of it, if it's occupied any signals leading into the block are red. This can be decided entirely locally (as in: local to the block). When a wheel sensor detects a wheel entering the block, the block is occupied, signals switch to red and the number of wheels is counted. As soon as another wheel sensor counts an equal number of wheels exiting the block the block is free and signals switch to green. You need a wire along the block to communicate this, but from a safety perspective there is no need for global communication.

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