Why is the subway so jerky?

Blackbird

Blackbird

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I’m currently on a redline train going from South Station to Broadway and it feels like every 5 seconds the train is starting to speed up then immediately braking. It’s very uncomfortable.

Update: It’s happened a couple of times between Broadway and Andrew, but doesn’t feel as frequent. Maybe it has something to do with the section. I don’t ride the southern side of the red line often.

Pulling out of Andrew was pretty painful. Twice the train really started to accelerate and stopped. One of the times, I thought someone was about to fall over.
 
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The suddenness of the braking would be from the ATO signal system assessing a speed penalty. That can happen when there's a signal problem, either lineside or with the onboard readout. Or can happen when an operator tries to go full-throttle through a speed restriction (or full-throttle through the aforementioned signal fault).
 
That sounds right. I literally just learned about this system last night while watching this guys video with a clickbait title. Its a surprisingly dense amount of information for 1 video, which is nice to see. Most youtube videos dont get so in depth on any topic out of fear of not appealing to very broad audiences. It was refreshing to come across a video with a bunch of the insider technical knowledge of the system.

 
Definitely a fun watch, lots of cool info. There were a couple things that raised my eyebrows though, particularly the idea that Porter is as deep as it is because... they accidentally bored the tunnel deeper than they were supposed to?
 
Blackbird said:
I’m currently on a redline train going from South Station to Broadway and it feels like every 5 seconds the train is starting to speed up then immediately braking. It’s very uncomfortable.

Update: It’s happened a couple of times between Broadway and Andrew, but doesn’t feel as frequent. Maybe it has something to do with the section. I don’t ride the southern side of the red line often.

Pulling out of Andrew was pretty painful. Twice the train really started to accelerate and stopped. One of the times, I thought someone was about to fall over.
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I typically ride the orange line and there is one driver in particular who never seemed to learn how to use the brakes correctly. It's an incredibly jerky ride--I've started carrying anti nausea meds for the times I end up on their train.

So I think there is some human error involved as well.
 
DwnTwnr said:
I typically ride the orange line and there is one driver in particular who never seemed to learn how to use the brakes correctly. It's an incredibly jerky ride--I've started carrying anti nausea meds for the times I end up on their train.

So I think there is some human error involved as well.
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Is it standard practice around the world to have a person directly controlling the speed of a subway? I’m not one to advocate for getting rid of human jobs, and perhaps it will always make sense to have a person in the front car in case of emergencies or system failures, but simple/regular trips between stations seems like something that could be controlled automatically to my layman’s brain.
 
Blackbird said:
Is it standard practice around the world to have a person directly controlling the speed of a subway? I’m not one to advocate for getting rid of human jobs, and perhaps it will always make sense to have a person in the front car in case of emergencies or system failures, but simple/regular trips between stations seems like something that could be controlled automatically to my layman’s brain.
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It's absolutely possible. There are a few levels of automation:

Level 1: Basic train protections, such as Positive Train Control on the Commuter Rail.

Level 2: Automatic Train Operation: This is basically what you described, where every train has a driver who can if necessary drive the train, but they usually don't have to. Doors are still operated manually and the train cannot automatically detect obstacles. Examples include the DC Metro, several London Underground lines, and basically any metro line constructed reasonably recently.

Level 3: Driverless operation: Every train has a member of staff somewhere, but under normal circumstances they're not driving the train, only operating the doors. The train is responsible for detecting obstacles, controlling its speed, etc. Examples include the London Docklands Light Railway, some assorted metro lines around the world, and the Disney World Monorail.

Level 4: Autonomous operation: Trains almost never have members of staff onboard, all operations are controlled remotely, even PAs. Examples include the Singapore MRT, Hitachi Automated Light Metro systems (Copenhagen, Brescia, Honolulu, etc), VAL systems (Lille, Rennes, Turin, etc), Vancouver Skytrain, and basically all people-mover systems like what you'll see at airports.
 
Thanks for the info! Does the T have plans to shift toward any of those less-manual systems in the future?
 
Blackbird said:
Thanks for the info! Does the T have plans to shift toward any of those less-manual systems in the future?
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I don't think there is anything official. The red line at least does have (very ancient) ATC already. I believe the new signaling systems would be able to eventually support more automation. Afaik in the US there are no (actual subway) systems that do.
 
Blackbird said:
Thanks for the info! Does the T have plans to shift toward any of those less-manual systems in the future?
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GL is slowly being upgraded to Level 1, and I believe RL and OL could become Level 2 with the new signalling system. Levels 3/4 seem unlikely at the moment, but if it happens anywhere I'd actually bet it will be the BL.
 
I don't know why, but, honestly, my eyes keep reading this thread title as "why is this forum so jerky?"
 
TheRatmeister said:
Level 2: Automatic Train Operation: This is basically what you described, where every train has a driver who can if necessary drive the train, but they usually don't have to. Doors are still operated manually and the train cannot automatically detect obstacles. Examples include the DC Metro, several London Underground lines, and basically any metro line constructed reasonably recently.
Click to expand...

Is Metro finally back to automatic operation? They'd basically completely abandoned that after the 2009 crash.
 
bakgwailo said:
I don't think there is anything official. The red line at least does have (very ancient) ATC already. I believe the new signaling systems would be able to eventually support more automation. Afaik in the US there are no (actual subway) systems that do.
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I think you could count the Honolulu and Vancouver Skyline services; they're elevated near-metro ops that are fully GoA4.

TheRatmeister said:
GL is slowly being upgraded to Level 1, and I believe RL and OL could become Level 2 with the new signalling system. Levels 3/4 seem unlikely at the moment, but if it happens anywhere I'd actually bet it will be the BL.
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I rather doubt that the RL and OL could move to GoA2 with the new signal system alone. As far as I know, CBTC is required for all current GoA2 and up systems, but the T's new signaling system is retaining the original fixed block system. Its just upgraded with modern microprocessor/ software controlled bits instead of electromechanical relays. Nowhere in the Alstom iVPI literature is there anything beyond speed and signal enforcement. That said since the new CRRC trains also are microprocessor controlled, adding a program and new equipment/ sensors to enable precise brake curves and stop points shouldn't be impossible. It'd probably be a prerequisite if we decide to go for platform edge doors.

Brattle Loop said:
Is Metro finally back to automatic operation? They'd basically completely abandoned that after the 2009 crash.
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According to WaPo, that should happen sometime this year. https://www.washingtonpost.com/transportation/2023/09/14/metro-ato-train-operations/

... Of course, they also said that a decade ago.
 
TheRatmeister said:
GL is slowly being upgraded to Level 1, and I believe RL and OL could become Level 2 with the new signalling system. Levels 3/4 seem unlikely at the moment, but if it happens anywhere I'd actually bet it will be the BL.
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The signal system for Red and Orange isn't changing in nature. It's just being optimized for tighter headways. Existing system, new fiber backplane, tighter signal blocks for the CRRC cars' brawnier acceleration and braking. But it's still the same old 1-bit ATO pulse signal setting the speed limit and enforced stops as before. The operator still has control within those enforced limits.

Blue Line Transformation is evaluating CBTC signaling, and Orange/Red's new fiber backplane will enable an upgrade to CBTC later. But the CBTC they're evaluating for Blue isn't fundamentally a whole lot different; it's like NYC's CBTC. It has moving blocks and positive controls for even more granular computer traffic control, but the operator is still manning a throttle within the parameters set by the system.
 
Stlin said:
As far as I know, CBTC is required for all current GoA2 and up systems
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The Victoria Line in London operated ATO with fixed block signalling all the way back in 1968, and the DLR opened with fixed block signalling and level 3 automation. It can be done.
 
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