[RossM]

I feel it's worth reminding that there's a difference between autonomous trains, driverless trains and unattended trains. The L train is considered Grade of Automation 2 - it starts and stops itself, though it has someone in the driver's seat who controls the doors and gives control to the ATO system. Driverless (GoA3) trains move that role to a train attendant who controls the doors from within the train. Unattended (GoA4) trains function without needing an on-board operator at all.

The driver probably is just sitting with a hand near the emergency stop button most of the time, but they're still required to pay attention. I imagine it's harder work now that they don't have to necessarily concentrate to operate the train.

I live in London, where a lot of tube lines are already (or soon to be) GoA2, with the introduction of a part-GoA2 mainline service this year (Thameslink). I don't think we'll see a GoA 4 tube for many years; aside from the obvious union rows, you've got safety concerns (primarily platform-edge-doors, which can't be retrofitted to cramped stations), and there's mixed public opinion on the idea of being stuck on a broken down train in a tunnel without on-train staff. Then again, people don't seem to acknowledge that the airport terminal transfers are unattended GoA4.

[jwr]

> I don't think we'll see a GoA 4 tube for many years

Perhaps I'm missing something, but I used to ride a fully automatic (e.g. there was no driver, not even a cabin for one) subway line in Lyon back in 1994/1995.

[bobthepanda]

I think they're talking very specifically about the London Underground.

It's very easy to build automated trains when they're brand new, but much harder to do so on legacy lines.

[T-hawk]

Including union demands for operators to exist and get paid as part of that legacy.

[comboy]

It would seem that GoA 4 is already out there in Denmark:

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

[bobthepanda]

Newer automated systems have the benefit of foresight, and usually contain walkways the length of a tunnel with evacuation cross passages.

In a legacy system like New York or London where these facilities don't exist and introducing them would be very disruptive, if not completely impossible, you probably need at least one person on a train to assist with evacuation.

[onion2k]

Does the DLR count as a GoA3 train? There isn't a driver sitting at the front.

[tialaramex]

Yes, each DLR train has a Passenger Service Agent, who is fully trained in the safe driving of a DLR train by a human, but during normal operation they're walking around in the train, closing the doors when it's ready to leave, and so on.

The PSA will drive the first train on each route every morning, since unlike the train's automation their human eyesight allows them to detect some very dramatic mistakes, for example if maintenance engineers left a metal trolley full of equipment halfway across the line, the train can't see that but the PSA can hit the "Stop" override. Normally they don't drive, allowing passengers to sit at the very front of the train, like on a roller-coaster, the manual controls are under a lockable panel.

The train also has a "full" manual mode in which the PSA is able to explicitly drive it wherever they want, rather than just stopping unexpectedly if they see a problem, but in this mode the train deliberately cannot reach its normal speed, because humans have poor reactions and so it would be too dangerous without the machine supervising.

[Symbiote]

That's correct.

[fredley]

The DLR is GoA 4. It wasn't exactly smooth sailing at first: https://www.youtube.com/watch?v=mwruoagYq0U

[Symbiote]

The DLR is level 3.

The video is from 1988 (good find!), but the only accidents ever to have occurred were under manual override.

The Copenhagen Metro is an example of a level 4 underground system. It's fairly new, so the tunnels all have an adjacent walkway which can be used in an emergency.

https://en.wikipedia.org/wiki/Docklands_Light_Railway#Accide...

[tzahola]

>but they're still required to pay attention

Like that Uber test driver?