Don't try to compare closed tracks to open tracks. A closed track is more like an elevator.
For an open system, you have to be able to respond to arbitrary visual input. For a closed system, there shouldn't be random stuff on the right of way.
At-grade ("Level") crossings should be closed (and thus grade separated). Where that's impractical there are numerous options for ensuring the crossing is not open to railway traffic until it is clear:
In some areas it can be practical to employ a person whose duties include verifying that this crossing is clear and then authorising its use. Because CCTV is cheap now we can fit cameras and lighting and have them do this remotely for a large portion of the network.
Or we can use radar to protect crossings. The barriers drop, and then radar is activated (the small hazard introduced by using radar is mitigated because the crossing is closed, nobody should be in the area being illuminated by the radar anyway), if somehow there is a large object on the crossing even though the barriers are down, this means something went wrong. The outward flow barriers re-open to potentially allow a trapped driver or animal to leave and the system tries again, if this doesn't help the crossing is considered failed and humans go to investigate, they will find your broken down semi-truck.
The freight car should preferably be harmlessly derailed by trap points. If this is impossible (and the layout cannot be rectified) the presence of the freight car should trip sensors, either axle counters or track circuits, and close the section to traffic. Again humans will likely have to come investigate how that occurred when it cannot be explained and won't go away.
At the crossing are boards indicating that this is a railway crossing, two sets of lights for each direction of traffic (two amber, one red in each set) and barriers, typically long motorised boom arms from which a flimsier but more visible structure hangs, plus a tall post with CCTV cameras mounted on it. The CCTV feed goes with all the other signal data to either a "signal box" not so far away, or a larger centre where many signallers work together. A signaller who wishes to move a train through the crossing views the CCTV feed, and initiates a sequence in which the lights show alternating amber ("caution, stop if possible"), then red ("stop"), the barriers close road lanes entering the crossing, then barriers close the road lanes which exit the crossing. The signaller verifies everything is as intended (e.g. no vehicle stranded on the crossing, no idiot pedestrians clambering over the barrier and standing on the railway) and then authorises trains to pass. Once as many trains as necessary have passed, the signaller closes the crossing to trains, and tells the crossing to re-open to road traffic, it raises the barriers and then switches off the red "stop" lights and road users can now use it as normal.
I'd take Amtrak to my hometown, and the engine would blow past the platform at 20+mph and still stop the passenger cars right on the platform. Riding on the train and it seemed like they'd miss it.
I think the weight of a car itself wouldn't change the theoretically possible stopping distance, since the momentum is proportional to the mass, but so is the friction between wheel and track, so mass cancels out.
Purpose-built automated lines often use smaller cars with more powerful motors sometimes concrete tracks. I suppose those help computers in flattening acceleration/deceleration curves and eliminating needs to compensate for weather or passenger counts.
There are GoA 4 systems in use in the world. The difference is that every DLR train has a trained operator onboard whereas in a GoA 4 system the nearest employees are in some distant operations centre, watching only via a CCTV connection. GoA 4 trains are entirely autonomous, if one were one day to somehow break down so badly as to be inoperable a separate team would need to go rescue it and meanwhile other trains would simply stop at a station and allow their passengers to disembark.
Usually there is no operator onboard. But is still GoA 3 because emergency situations are handled by operators from a control room.
Look around, you will see there is a person wearing a uniform who is perhaps helping tourists figure out where they need to change trains, or assisting a woman struggling with shopping and a push chair. These are TfL employees trained to drive the train, even though it's autonomous.
Before the train leaves, even under normal autonomous operation, this person in the uniform activates a "close doors" control and this is the only reason a DLR train will close its doors. When the doors are closed and the way ahead is clear the train will drive itself to the next station, and open the doors, the cycle repeats.
The person wearing the uniform is trained to safely operate a train. Any time they're on first shift they actually sit at the front (usually occupied by excited children) and unlock the onboard controls to literally drive the train for route verification purposes. Autonomous trains aren't looking, and tools or equipment may be left on the track by work gangs (despite a "count it out, count it in" procedure) so the first trip of the day is always done manually.
You can't drive a DLR train from the control room.
The original intent of the Black Mesa & Lake Powell (hauling coal to a power plant) was for it to be fully automated, but I don't know if it ever ran without a human in the cab.
I didn't know about that, but is it a "freight line" or a "freight train"? If it is the former, a dedicated line used only by the automated train, then it isn't all that removed from disneyworld: a single-use train on a dedicated line. And Australia is notoriously flat.
I'm from the west coast, where driving a heavy train through the mountains is serious business, but disasters can happen anywhere. The latest epic disaster in Canada was caused by a train that was unmanned at the time. It was parked.
https://en.wikipedia.org/wiki/Lac-M%C3%A9gantic_rail_disaste...
Maybe the gnarliest scenario I know of out there is: There's a major brush fire on Cajon. Like, 20-foot-high wall of flame. Is it far enough away for you to try to get the train past it? (With maybe 4000 gallons of diesel fuel under each locomotive, and maybe liquefied petroleum gas tank cars in the consist?) Or do you park the train, and hope the fire doesn't come to you? I mean, I guess an AI can make that decision without being influenced by concern for its own survival. But I suspect that most train-driving AIs don't have a really good set of training data for this scenario...
I suspect most human drivers don't either. The AI might not make a particularly good decision, but is there any reason to believe that a human would make a better one?
https://www.railjournal.com/freight/rio-tinto-completes-auto...
"Australia is notoriously flat"
Citation needed.
"Australia is the lowest, FLATTEST, and oldest continental landmass on Earth[4] and it has had a relatively stable geological history. Geological forces such as tectonic uplift of mountain ranges and clashes between tectonic plates occurred mainly in Australia's early prehistory, when it was still a part of Gondwana. Its highest peak is Mount Kosciuszko at 2,228 metres (7,310 ft), which is relatively low in comparison to the highest mountains on other continents."
https://en.wikipedia.org/wiki/Geography_of_Australia
Russia is big. Switzerland is small. And Africa has gets less snow than Canada. (Citations needed)
The basic route of this train (Newman to Port Headland) is a gentle slope to the coast. +175 and -700m over a 400km journey. (Google maps) Compare that to a route in western canada: Canmore Albert to Salmon Arm BC, the same distance but +2500m and -3500m.
It still snows in Africa, and if you tried to climb Jebel Toubkal without a jacket I don't think knowing that Canada is snowier would provide you much comfort.
Also, Line 14 on the Paris metro (heavy use) has been automated since the 90s.
https://www.bbc.com/news/world-us-canada-42421417
From the wikipedia article on Positive Train Control (PTC):
>In December 2010, the U.S. Government Accountability Office (GAO) reported that Amtrak and the major Class I railroads have taken steps to install PTC systems under the law, but commuter rail operators were not on track for the 2015 deadline.[14] As of June 2015, only seven commuter systems (29 percent of those represented by APTA) were expecting to make the deadline. Several factors have delayed implementation, including the need to obtain funding (which was not provided by Congress); the time it has taken to design, test, make interoperable, and manufacture the technology; and the need to obtain radio spectrum along the entire rail network, which involves FCC permission and in some cases negotiating with an existing owner for purchase or lease.[15]
https://en.wikipedia.org/wiki/Positive_train_control
So needless to say... the technology likely exists today, but implementing anything significant to existing infrastructure in the US is a monumental feat.
The above example is just a safety system, but once you start removing employees you also start running up against labor unions... which is yet another layer holding things back.
However, the nationwide freight network is interconnected by many different companies, in various states of repair, with various states of mechanization. I live near a bunch of grain processors and when they are taking deliveries it is a lot of manual switching and back and forth to get each plant's cars to the right lines.
Could it be automated? Yes, the technology is available, you 'just' have to implement it. Will it be? Probably not anytime soon.
The future is now: there are automated rail lines in a numbers of cities around the world. Some are relatively old, too.
The JFK AirTrain is one such example.