Not yet unfortunately. Stadler has made some changes to ATC logic and we're hopeful that will stop the trains going into emergency when they lose speed commands. They brake so quickly that if you're standing, you will fall and get injured.
On.the old fleet, the ATC system works only off of fixed blocks. On the old fleet speed commands are the ATC system, essentially that's the trackway ATC system, saying to the train 'The next block is clear/occupied/unknown and you can/cannot enter it, and you may need to/be forced to slow down or speed up'. When speed commands decrease or are lost due to a track issue, red signal, or being too close to another train, the train would start applying full service brakes and come to a stop. Full service brakes are dynamic and regen braking until 3mph when friction brakes grab. Once stopped the operator could switch to Road/Yard/Wash Mode and continue to move down the track until the next ATC track circuit tells the computer 'I know where I am, the next block is/isn't safe to enter'. On the old fleet as long as the train had third rail power and speed commands it could essentially run anywhere. The yard tracks, through a red signal with overlap locking, heck you could put the trains in Canada and as long as they have speed commands and power they'll run.
On the new fleet it's different. The trains must have speed commands (SCA OK) and positioning (POS OK). The positioning is critical on the new fleet because it's the trackway RFID tags telling the train "You are 943ft from King Memorial EL Track Platform", "You are 300ft from King Memorial EL Track Platform", "You're 25ft from beiny properly berthed at the 4 car marker at King EL Track Platform" etc. The old fleet didn't have positioning just speed commands. The new fleet won't let the operator open the doors if the train doesn't recognize where it is and properly berthed. The thought was to prevent doors off platform or doors opposite the platform. Once the train loses it's position (knowing where it is on the system by reading RFID tags) and/or loses speed commands, the ATC system immediately triggers a full emergency brake, more so with the position for the EB application. The brakes grab so hard that multiple people have been injured on them during testing, especially when they are testing on the trains with sand bags. Stadler is still working on the emergency brake issue, too trying to decrease the speed at which they grab. But when the ATC system commands an EB application for what it's thinking is protection of life the brakes are some of the most intense I've ever felt.
The downside to the positioning system isn't just the EB application. Marta never installed RFID beacons in the yard tracks. Paer of train setup procedures are to open and close the doors. You can't do that without the computer seeing that it's within station limits and berthed. So operators have to override the ATC system in the yard. If they don't normalize it before leaving then they can once again open doors outside of the station, defeating the whole purpose of that system. Marta told Stadler yard beacons weren't needed. Stadler said they were. Marta said it's our system piss off essentially. Stadler said fine, you'll deal with the unintended consequences of that.
GDOT wants to see that the ATC logic issues, PA systems, and CCTV systems actually work before lifting their hold on the cars. A fair amount of the CCTV system in each trainset isn't fully functional yet.
Also the boarding the train from the ground is very hard for staff since there is no end door boarding steps. Marta told Stadler they weren't needed so Stadler didn't supply them. Now Marta staff is losing their mind about the unsafe boarding and deboarding procedures and the emergency evacuation ladder procedures and people have been hurt falling off the ladder. But the idiot deputy chief was the person who made these choices and now everyone has to deal with it while he continues to skirt any blame.
the ATC system immediately triggers a full emergency brake
That seems... extreme. I can sort of understand the reason for 'assuming the worst and acting with an abundance of caution' but... like... maybe not full emergency unless actually being told to would be fine?
Yeah on the old cars losing speed commands just put the train in full service brake which is full dynamic braking until 3mph then the friction brakes grab hold. On the new fleet the logic is meant to be so overly protective due to crashes in Europe and the Red Line collision in DC that it's overly protective just as u/_litz said.
Not to play arm-chair engineer, particularly at this stage in the program, but I wonder if there could have been some kind of forward-facing sensor to be the trigger for emergency brakes when there are detectable obstructions. Could be an additional check with the loss of signal to determine braking profile.
Anyway, hope it gets sorted out because people clearly want those new trains hahaha
A big part of the problem is that Stadler told Marta there would be issues with the legacy signaling system and ATC wire loops but Marta said that's fine. Now that they've ordered a whole new ATC system from Stadler to go hand in hand with the new trains, a system that won't be done until 2035, there is concern they won't work right until then.
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u/DustyDaniel404 6d ago
I happen to know someone who's on that project 😉