Smoke incident near L'Enfant Plaza 1/12/201

[JDC]

It doesn't all make sense yet in my mind. Does an "arcing event" lead to circuit breakers switching off?

It depends on how much current is being pulled. In normal usage, the circuit could draw thousands of amps

I've seen comments posted on various websites mention that there was also a large standing pool of water in the tunnel, but no reference to where this alleged fact originated.

[smallfire85]

It doesn't all make sense yet in my mind. Does an "arcing event" lead to circuit breakers switching off? If so that would explain why the train stopped.
I find it hard to believe that the arcing led to breakers shutting off the power right away, because if there was really no fire as in the quote above, and the arcing was stopped from the power being off, what was creating all the smoke for that 30 minutes or so? There must be more to the story, like the burning 3rd rail covers as posted earlier (are they made of plastic???).
JS
Or are voltage oscillations from the arcing enough to stop the train?

Correct me if I'm wrong, but from what I know electtrical arcing is more or less a smaller scale version of lightning. I've heard that third rail arcing has the potential to weld shoe to rail, but the motion of the train usually prevents that. My non-official assumption is that the train entering that electrical block could have pulled enough juice to exploit a possible low resistance point near a feeder cable, which could have caused an arching event between the cables and a grounded source. This could have heated the conductors to the ignition point of the insulation, which would account for all the smoke and none of the fire. But that's all speculation.

If there was an extended arcing event involving a feeder, then that could be enough to trip the breakers, which would render the third rail powerless.

[JDC]

Newest WP story, including additional details from NTSB: http://www.washingtonpost.com/local/tra ... story.html.

"The preliminary report said arcing occurred about 1,100 feet in front of the train, which was traveling southbound from the station toward the Pentagon Metro station. . . . Though there was no immediate indication that the train caused the arcing, the NTSB said investigators would examine it Tuesday. Arcing is often connected with short circuits and may generate smoke."

[smallfire85]

"Though there was no immediate indication that the train caused the arcing, the NTSB said investigators would examine it Tuesday. Arcing is often connected with short circuits and may generate smoke."

Well, there goes my theory...

[litz]

The power is there regardless of the presence of the train ... the train merely taps it in order to travel.

The train does, however, induce a current flow, and if there was a conductor incapable of handling the current flow (and remember, we are talking about a train accelerating out of a station, so much more current than simply traveling along), it's well and truly possible that induced a failure. These current flows are huge, on the order of a thousand amps or more, at (I think) 750vdc. Put in perspective, that's approaching a megawatt or more.

Once all that stuff heated up from the arc (and sparks from the arc), cutting off the power merely removes the heat source that started things off ... anything overheated and burning is going to keep doing so until it's fuel is exhausted.

Think about it like this ... there's a short circuit in your house, which catches the inside of the wall on fire. Turning off the power doesn't put out the fire in the wall.

NTSB will get to the bottom of this, and quickly ... it happened almost in their backyard.

[mmi16]

Newest WP story, including additional details from NTSB: http://www.washingtonpost.com/local/tra ... story.html.

"The preliminary report said arcing occurred about 1,100 feet in front of the train, which was traveling southbound from the station toward the Pentagon Metro station. . . . Though there was no immediate indication that the train caused the arcing, the NTSB said investigators would examine it Tuesday. Arcing is often connected with short circuits and may generate smoke."

Virtually every electric circuit has circuit breaker or fuse protection do deal with short circuits.

Did a breaker trip, if so, was the trip level actually too high for the circuit? If not, why?

[JackRussell]

Did a breaker trip, if so, was the trip level actually too high for the circuit? If not, why?

The trip level needs to be several thousand amps to allow for normal operations of the trains. I don't know the specific numbers, but it is going to be somewhere in that neighborhood.

[smallfire85]

The power is there regardless of the presence of the train ... the train merely taps it in order to travel.

The train does, however, induce a current flow, and if there was a conductor incapable of handling the current flow (and remember, we are talking about a train accelerating out of a station, so much more current than simply traveling along), it's well and truly possible that induced a failure. These current flows are huge, on the order of a thousand amps or more, at (I think) 750vdc. Put in perspective, that's approaching a megawatt or more.

Once all that stuff heated up from the arc (and sparks from the arc), cutting off the power merely removes the heat source that started things off ... anything overheated and burning is going to keep doing so until it's fuel is exhausted.

Think about it like this ... there's a short circuit in your house, which catches the inside of the wall on fire. Turning off the power doesn't put out the fire in the wall.

NTSB will get to the bottom of this, and quickly ... it happened almost in their backyard.

Yeah, that's pretty much what I meant to say, though you said it much more eloquently. I know that the third rail cables on the Long Island Raiload are supposed to be rated at 3000V/2000A, so I would guess that WMATA would be in that neighborhood.

[JDC]

Metro has released an update that the affected train has been moved to a rail yard for further investigation and that all operations are back to normal as of about 8 pm. A separate alert indicated that the train was being moved north to the greenbelt yard.http://www.wmata.com/about_metro/news/P ... aseID=5855

[Mainland]

There's a longer 14 minute video from inside the train here:

https://www.youtube.com/watch?v=iafvfMx ... e=youtu.be" onclick="window.open(this.href);return false;

The operator makes repeated announcements to stay in the train and not go into the tunnel. However, he's also heard pleading with any transit police on the train to communicate on their end to release the train on the platform at L'Enfant.

It appears after listening/watching to the video in full that there were communication issues somewhere in the chain. (And this is to say nothing about the apparent problems DC Fire had with their radios in the tunnel...) I'd say it's possible another SB Green or Yellow line train pulled into L'Enfant in the interim time before the affected YL train communicated the smoke ahead. However, it would seem for nearly 10 minutes a train continued to block progress to reverse out of the tunnel. Could third rail power have been out (if indeed it were cut) at L'Enfant too?

[YOLO]

There are rumors going around that an another train was at L'Enfant Plaza blocking the incident train from reversing. The operator on that train saw the smoke and ran for the hills, and Metro could not find an another operator to pull it out of there for 10-15 minutes. Unconfirmed, and we won't know until NTSB says something.

[pumpers]

Still can't figure out why the train stopped (automatically or by the operator), and if something like a 3rd rail cover was burning, even though it has officially been said there was no fire. This rumor about not being able to back up because another train was was in the way makes it sound like power was on for quite a while. The rumor also has the ring of truth, but I guess we will have to wait.... JS

[JackRussell]

Still can't figure out why the train stopped (automatically or by the operator), and if something like a 3rd rail cover was burning, even though it has officially been said there was no fire. This rumor about not being able to back up because another train was was in the way makes it sound like power was on for quite a while. The rumor also has the ring of truth, but I guess we will have to wait.... JS

Once the 3rd rail is cut, the lights will go out for the most part (except for emergency lights). The passengers would be able to tell us roughly how long they were at a standstill before the lights went out.

I hope the rumor about the other driver going AWOL isn't true.

[jkovach]

The lights are certainly out in the video posted above. From coverage elsewhere (the Post), it sounds like the lights went out fairly early during the incident. I've been assuming that the lights went out due to the third rail power being cut, but of course have no way of knowing for certain.

In the video, the operator is saying he is attempting to get the train moved back to the platform at L'Enfant. But if third rail power was off, how were they planning to move the train? Did someone somewhere think they could get the power turned back on? Was the power actually still on with the lights being out for some other reason? Guess we have to wait for the report...

[JDC]

DC has released a preliminary timeline of the incident: http://www.nbcwashington.com/news/local ... 81381.html


3:14 - Metro Rail’s Unit 22 called to report a debris fire on the tracks at Gallery Place Station, upper and lower levels.
3:19 - Engine 02 Unit Dispatched to 7th St NW/H St NW (Gallery Place Metro)
3:18 - A caller from a construction site reported smoke coming out of the Metro tunnel at 9th and Water St SW
3:22 - Metro Rail’s Unit 22 called to advise of heavy smoke at L’Enfant Plaza Metro upper level
3:22 - Engine 02 Arrived at 7th St NW/H St NW (Gallery Place Metro)
3:24 - Metro Transit Official called requesting medics and fire units at L’Enfant Plaza Station for smoke in the station and reported citizens in the station could barely breathe
3:25 - FEMS units arrived at 9th St SW/Water St SW scene where there was an odor of smoke but no flames were seen
3:27 - A caller at the entrance of L’Enfant station requested an ambulance
3:28 - Metro box alarm was dispatched to 7th & D St SW; EMA is notified
3:31 - Rescue 1 arrives (1st unit) at 7th and D St SW L’Enfant Station; MPD is dispatched
3:32 - MPD unit 1D 1011 arrives
3:32 - A caller at the entrance of L’Enfant station requested an ambulance
3:33 - A caller on the yellow line, in the tunnel stated the train was filled with smoke
3:33 - A caller said he was “at or on” the Pentagon train and was transferred to Arlington 911 Center. The OUC call taker remained on the line and updated CAD which reflected this call
3:35 - Engine 02 Unit cleared Gallery Place Metro and dispatched to L’Enfant Plaza
3:39 - A caller on the train advised that it was filling with smoke.
3:42 - A caller from a street location of 7th and E Street SW reported his wife was having difficulty breathing after she exited L’Enfant Station
3:42 - Repeat caller from 3:33 – made inquiry “if help is on the way” the caller provided the train number 3031. He was transferred to the Metro Transit Official who told him not to leave the train because the tracks were still live
3:43 - A caller advised he was stuck on the train and it was filling with smoke
3:44 - BFC advises that WMATA confirms that power is shut down; there is a train with people trapped
3:45 - A male caller asked “if help is on the way because the train is filling with smoke”
3:45 - A female caller asking if help is on the way because the train is filling with smoke
3:46 - A second alarm dispatched
4:09 - Battalion Chief 1 advises he is at Operations Command Center and there is a report of a patient having a seizure on the train; squad 1 advises 9th and D; and an adult female is undergoing CPR, requesting a medic
4:12 - Medic 14 advises he is a block away from L’enfant plaza and will respond; Medic 6B responds that he is closer, medic 14 cancels the run
4:17 - Medic 6B is given the corrected location on channel 0A12, 9th and D St SW
4:19 - Command 2 directs all medical units on L’enfant Plaza to switch to 0A5 (tactical channel due to radio traffic)
4:25 - Medic 27 transports patient to GW, CPR is still in progress