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Comment by dragontamer | Hacker News Reader

> could we have had an autonomous rail system by now?

We already have autonomous rail systems. Its called positive train control and was fully implemented like a year or two ago (mandated in 2009, but you know how government works, lol) https://en.wikipedia.org/wiki/Positive_train_control

The train conductor has become more-and-more automated to remove the chance of human error. It works with a system of very reliable sensors that indicate where every train engine is on the rails.

Given the huge amount of cargo any particular train has, I don't think there's any intent on cutting the last two humans (the conductor + engineer) out of their job. Their salary costs are miniscule compared to the safety value they deliver, even if the job of driving a train has been almost entirely automated away by now.

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Paris got its first autonomous metro line in 1998. It was developed in ADA. http://archive.adaic.com/projects/atwork/paris.html

Using the B method: https://en.wikipedia.org/wiki/B-Method

https://link.springer.com/content/pdf/10.1007%252F3-540-4811...

https://arxiv.org/pdf/2005.07190.pdf

All this was developed in the 80's and 90's. It would be interesting to see how this evolved. Obviously with a ML/AI approach it would be different now. Although there might be some ways to specify some constraints or boundaries to an AI system, for safety, comfort, physics, etc.

> Obviously with a ML/AI approach it would be different now.

Is it? The theory of block signals and path signals don't change because AI was invented. And I have my doubts that AI could do better than path-signal algorithms.

https://en.wikipedia.org/wiki/Railway_signalling

OpenTTD players, wassup? You can run these block signals / path signals in video games. Its a bit complicated to setup and the terminology is arcane... but the algorithms aren't so advanced that they require "AI" or anything. (If at block signal, wait until exit signal is ready. Etc. etc.). Its actually pretty fun (OpenTTD is a videogame built around these signals!!), because if you mess up your signals, you get deadlocks and/or "race conditions" (aka: risk of a deadly crash). But once you get used to the methodology, you can build incredibly complex junctions that automatically and safely routes trains everywhere.

That's why you had legions of railway nerds playing with trains in their basement all day: they're trying to get their path signals / block signals / chain signals correct so that those toy trains traverse their toy-tracks automatically without crashing. These concepts were like, from the 1930s or something (Path signals are newer)

EDIT: Apparently "before 1923": https://www.amazon.com/gp/product/117705681X. Definitely an ancient and arcane art of old wizards. Railway engineers were dealing with semaphores, race conditions, and deadlocks __LONG__ before us programmers even existed!!

I wonder if, for the cost spent on CPU-and-engineer-driven research and development of autonomous cars, if we could have had nationwide autonomous rail rolled out.

https://railroads.dot.gov/train-control/ptc/positive-train-c...

> On December 29, 2020, FRA announced that PTC technology is in operation on all 57,536 required freight and passenger railroad route miles, prior to the December 31, 2020 statutory deadline set forth by Congress.

We got that. We literally got that.

I suspect the OP may be more interested in nationwide, convenient, affordable, automated passenger rail.

Which in the US is possibly (?) several orders of magnitude more in terms of capital investment compared to both electrifying the entire ICE fleet and automating it.

The majority of the costs of passenger rail is in the land-costs of placing those statins (and rail-lines) somewhere important.

The US Freight Rail network is just the right place to deploy this technology right now. We may have crappy passenger systems, but our freight is world class.

EDIT: It should be noted that PTC sensors cost $50,000 per train. But each train costs $2+ million, so the PTC sensors aren't that much compared to the overall system. The idea of having a similar suite of $50,000+ sensors / radios on every car is clearly too costly in contrast.

Nope, requires a sane society that gathers around and does whats best for the collective whole. What we have, however, is a kleoptocracy, and being as such, the opportunity to extract more wealth, faster, and easier, existed with selling the promise of autonomous vehicles. If the same incentives existed for autonomous rail, it would have happened already.

Let’s not be so cynical here. No amount of mustache-twirling evil robber barons would change the fact that for any nationwide rail system to be useful at a last mile, billions (if not trillions, if we’re talking coast to coast) of dollars of existing real estate and infrastructure would have to be bulldozed, or else you end up with California’s joke of a Central Valley rail that will never connect Los Angeles to San Francisco and recreate the Shinkansen miracle between Tokyo and Osaka.

In other words, the problem is not a matter of engineering (it can be built) or finance (it can be funded) - it’s politics.

> existing real estate and infrastructure would have to be bulldozed,

You mean like they've done with every beltway and interstate? They claim eminent domain, take whatever strip of land they need from you, and bulldoze anything in it's path to build nice fancy exits full of the same features: a few hotels/motels, gas stations, couple of fast food chains, and, perhaps, if you are fancy enough, a strip mall with a Department store, Sporting Goods, and a fine dining establishment from one of America's most recognized brands: Bloomin' or Darden

There was a push for something like that and it would have been great...it fell afoul of NIMBY and Toll road haters. https://en.wikipedia.org/wiki/Trans-Texas_Corridor Everyone in Austin hated SH-45 & 130 when they were built, they were practically empty for a few years to my delight as I could travel the entirety of Austin in a fraction of the normal time even during rush hours. After MOPAC was added residents began to see the light and the tollways are now congested. Many are regretting their opposition to Perry's lost/last road project but, that train has left the station unless Elon can get the Boring project going or Virgin is able to implement their version of Hyperloop. Hell, I'd have settled for elevated wire gondolas over the roads, works well enough for Australia.

Not for passengers. You still need conductors, if for no other reason to be the equivalent of flight attendants (there for extremely rare safety incidents -- deaths per passenger mile are higher for trains than planes -- to manage unruly passengers, etc.)

No because its a political and labor relations problem not a cost problem

Probably not, that's likely a hundreds of billions of dollars investment, whereas I imagine self driving investment totals a couple tens at the most.

Remember that derailment/near derailment that happened when someone cut the electrical circuit connector cable on some rails, which then prevented the system for knowing where the train was?

PTC, from my understanding, is that the train gets "positive orders" from a central server. The central server says "It is safe to move through X", and the train then moves through X.

If the sensor in X is broken, then the server will say "I cannot prove it is safe to move through X", and the train will stop.

I'm not a transportation engineer however, so I'll defer to anyone with actual experience in the field. But the idea is that our sensors are so effective today, that it is better to "prove" each leg of the journey is safe with "positive train control", rather than the opposite normal approach. (Ex: Sensor detects a problem, which stops the train).

That is to say: all sensors in the USA are in positive-train control mode. Trains will therefore stop if any sensor malfunctions. We're now in a "default stop" state for all trains, unless those sensors are working, deployed across USA.

Wow that sounds like a fantastic failure mode for a busy freeway on a prime commute day when someone nefariously interferes with the system.

Tracks fail all the time due to natural disasters... or even just wear-and-tear (heat causes expansion / contraction of lines). Or snow covering an area, making the tracks unsafe.

The answer is simple: a 2nd or 3rd track for redundancy. Which is needed for maintenance purposes anyway. And flamethrowers for snowy areas.

From this perspective, the infrastructure to prove a line of track is safe is just "part of the cost" of a modern rail line. And any such failure is fixed as part of the maintenance costs.

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In any case, if you really wanted to stop a train during rush hour or something, I suggest a crowbar on the rail lines. There's easier ways to derail a train, and sabotage is a known problem. Physical security measures are available, camera systems etc. etc.

But a saboteur with a crowbar is roughly the same problem as too much snow on any given track. We definitely have more to worry from Mother Nature rather than our fellow man (at least.. for now).

Just break the traffic lights of a few busy intersections near the freeway. If they are in any way like the ones in my home country then the only protection for the cables is a cover locked in place by a single screw.

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