WMATA Red Line Collision

[Ryan]

Greater Greater Washington, a local trainsit-oriented blog published a great explanation of how the control system is supposed to work on Metro trains and some of its shortcomings:

http://greatergreaterwashington.org/post.cgi?id=2695

It's a very well written, easy to follow (even for someone with a degree in Political Science like me) writeup.

 

[Neil_M]

Heavy enough to not disintegrate the way the 1k car did on impact.

Ok, so what speed would you recommend having your collision at?

 

[AAARGH!]

I saw on CNN where the NTSB indicated the rear (moving train) train's controls (dials, control stick, etc...) were all found to be in the automatic position, suggesting computer failure and not the operator's error. They also stated the emergency brake 'mushroom' button was depressed and the brakes on the first car had the tell-tale blue markings indicated they were in emergency brake mode. However, they could not yet estimate how far away the brakes were applied.

 

[PRR 60]

I saw on CNN where the NTSB indicated the rear (moving train) train's controls (dials, control stick, etc...) were all found to be in the automatic position, suggesting computer failure and not the operator's error. They also stated the emergency brake 'mushroom' button was depressed and the brakes on the first car had the tell-tale blue markings indicated they were in emergency brake mode. However, they could not yet estimate how far away the brakes were applied.

It suggests an ATC failure, not necessarily computer failure. There are lots of elements in the ATC system from track circuity and wayside relays to the on board systems that control speed compliance. Note that the ATC system is active even if the train's ATO is cut-out, so even in what the media is calling "manual" operation, the operator could not make an error that would result in a collision.

 

[AAARGH!]

It suggests an ATC failure, not necessarily computer failure. There are lots of elements in the ATC system from track circuity and wayside relays to the on board systems that control speed compliance. Note that the ATC system is active even if the train's ATO is cut-out, so even in what the media is calling "manual" operation, the operator could not make an error that would result in a collision.

They also indicated they would be looking very closely at the track once the debris was cleared today. PRR, this correlates to what you state about track circuitry, etc...

Does anyone know what percentage of the WMTA's cars are 1000 series? If they have to replace them, how many are there?

 

[Ryan]

About a quarter overall.

The problem is that the delivery of the 6k cars just completed, and the RFP for the 7k cars just went out, so there's a lot of design work in the pipe before WMATA gets anything new (unless they go back and order more 6k cars). The 7k order was going to be a big one - enough to replace the 1k cars and add enough new cars to expand service to Dulles on the Silver Line. If the decision is made to start retiring the 1k cars early, look for shorter trains and more crowds in the future.

 

[VentureForth]

A comprehensive article in the Washington Post has a pretty good list of possibilities. One question I have which was brought up before but I haven't heard today was why the first train was stopped. Here's a possible scenario: Circuit problem in track causes first train to stop. For some reason it uses a technology not updated in train 2. But if track circuitry was intermittent, is there not some sort of checksum that would light up the control board at HQ?

More questions: they keep touting that the 1000-series cars needed to be reinforced or replaced. I haven't read anything about their electronics being upgraded. Was that ever done?

Why is there evidence that the emergency brake was: engaged in the cab, showed wear on the rotors and showed wear on the tracks; yet no one felt the train slow down?

 

[Ryan]

The first train was stopped because there was a 3rd train stopped at the platform loading/discharging passenger at Ft Totten station.

 

[AlanB]

More questions: they keep touting that the 1000-series cars needed to be reinforced or replaced. I haven't read anything about their electronics being upgraded. Was that ever done?
Why is there evidence that the emergency brake was: engaged in the cab, showed wear on the rotors and showed wear on the tracks; yet no one felt the train slow down?

Well if the electronics were updated, one thing that they didn't do was to install black boxes.

As for the second question, first witness testimony is always unreliable. Second, judging from the satellite shot of the curve where the accident happened, I'd say that the poor operator probably had less than 20 seconds warning that she was in trouble. That probably means that the brakes were on for no more than 15 seconds or so. That would barely be enough to really make a noticable difference in speed prior to the impact. Even if someone did realize that the train was slowing, they would probably just attribute it to the collision itself.

 

[Tony]

I would think it is just regular human nature to expect (1) computers never make mistakes and (2) the computer will automatically correct for any mistakes. Given that, the operator might have had a long reaction delay while she attempted to resolve that consistency, between her faith in the system and what she was seeing, in her mind.

 

[WhoozOn1st]

In a SoCal take on the D.C. wreck situation, L.A. Metro Rail and Metrolink folks are watching the investigation closely. The Red and Purple lines use Alstom signaling equipment similar to the D.C. Metro's, and Metrolink is in the midst of installing an automatic train stop system in the wake of last September's deadly UP/Metrolink cornfield meet.

MTA keeps tabs on D.C. crash inquiry

 

[George Harris]

AThe WMATA cars are all lightly built. Strength can be had without excessive weight, but the car builders in Europe and elsewhere propogandize that such is not possible. Management buys into that so does not require the strength that they ought to.

Still banging that old drum? Best way to survive a crash is not have one in the first place. Anything else is just window dressing.

Yes I am, and with no apologies to anybody for doing so. These people that are trying to sell glorified tin cans as rail cars have blood on their hands as far as I am concerned.

If you think all accidents are preventable, you do not live in the world of reality.

 

[WhoozOn1st]

From an NTSB wreck investigation update issued today:

"Investigators found metal to metal compression streak marks on both rails of the track for about 125 feet ending near the approximate point of impact, consistent with heavy braking.

"Investigators conducted tests at the accident site last night with a similar train and found that when the train was stopped at the same location as the stopped struck train, the train control system lost detection of the test train." (emphasis added)

Full press advisory:

NTSB ISSUES UPDATE ON INVESTIGATION INTO COLLISION OF TWO METRORAIL TRAINS IN WASHINGTON, D.C.

 

[Spokker]

Yes I am, and with no apologies to anybody for doing so. These people that are trying to sell glorified tin cans as rail cars have blood on their hands as far as I am concerned.
If you think all accidents are preventable, you do not live in the world of reality.

We should all drive Hummers then. Those who sell Hyundai Accents have blood on their hands.

 

[Spokker]

I would think it is just regular human nature to expect (1) computers never make mistakes and (2) the computer will automatically correct for any mistakes.

The software is programmed by a human, and humans are fallible, so software will always be fallible.

 

[Ryan]

Yes I am, and with no apologies to anybody for doing so. These people that are trying to sell glorified tin cans as rail cars have blood on their hands as far as I am concerned.
If you think all accidents are preventable, you do not live in the world of reality.

We should all drive Hummers then. Those who sell Hyundai Accents have blood on their hands.

Not really, all cars sold in the US have to live up to some pretty tough crash safety standards.

That said, my transportation to/from the train station is a Chevy Suburban.

 

[George Harris]

Yes I am, and with no apologies to anybody for doing so. These people that are trying to sell glorified tin cans as rail cars have blood on their hands as far as I am concerned.
If you think all accidents are preventable, you do not live in the world of reality.

We should all drive Hummers then. Those who sell Hyundai Accents have blood on their hands.

The difference is that YOU chose the Accent or whatever four wheeled tin can you bought, and presumably understand the trade-offs. Having a number of years ago seen the aftermath of a accident between two trucks where the police and wreckers did not know that there was a Pinto between them until they pulled the trucks apart, I am inclined to avoid very small cars, even if it means that I drive less to keep my gas bills from being excessive.

 

[Spokker]

The difference is that YOU chose the Accent or whatever four wheeled tin can you bought, and presumably understand the trade-offs. Having a number of years ago seen the aftermath of a accident between two trucks where the police and wreckers did not know that there was a Pinto between them until they pulled the trucks apart, I am inclined to avoid very small cars, even if it means that I drive less to keep my gas bills from being excessive.

No, not everybody can afford huge trucks and must purchase economy cars to stay mobile.
We all choose what our rail systems are like by voting for representatives that do not care about rail transit and fail to fund it properly. We chose this by striking down rail-related measures in the past, or not getting them on the ballot at all. Only this past year have some of those mistakes been rectified, but it's not enough as the nation's rail fleet is badly aging. http://www.nytimes.com/2009/06/25/us/25tra..._r=1&ref=us

Rail systems, even DC Metrorail, continue to be statistically safer than driving a personal automobile. You are probably more likely to be killed in an auto accident on the way to the station than while riding on the train.

 

[TVRM610]

Why is there evidence that the emergency brake was: engaged in the cab, showed wear on the rotors and showed wear on the tracks; yet no one felt the train slow down?

I have personally been on several trains going into emergency ( twice on Amtrak, multiple times on shortlines) and the E-Break is not instant. Several seconds usually pass between the sound of the air dumping and the abrupt stopping of the train.

Like Alan said, by the time the E-brake was pushed till the impact, there would have most likely not been any noticeable slowing of the train.... it all happened in seconds. If the train had slowed any... the accident would have been much more manageable. This train had to have been really moving for this type of accident.

Just like the metrolink accident in Cali... it is so unfortunate that this happened at such a blind curve, if this had been in a straight section, the engineer would have seen the train in time.

 

[jackal]

Why is there evidence that the emergency brake was: engaged in the cab, showed wear on the rotors and showed wear on the tracks; yet no one felt the train slow down?

I have personally been on several trains going into emergency ( twice on Amtrak, multiple times on shortlines) and the E-Break is not instant. Several seconds usually pass between the sound of the air dumping and the abrupt stopping of the train.

Like Alan said, by the time the E-brake was pushed till the impact, there would have most likely not been any noticeable slowing of the train.... it all happened in seconds. If the train had slowed any... the accident would have been much more manageable. This train had to have been really moving for this type of accident.

Just like the metrolink accident in Cali... it is so unfortunate that this happened at such a blind curve, if this had been in a straight section, the engineer would have seen the train in time.

I've actually plugged railcars (by uncoupling from them and having the air hoses separate) and then watched the brake piston (clearly visible on freight cars) actuate. It really is a several second delay before the piston moves and probably a good 8-10 seconds before it is fully engaged (the piston is fully out) and probably more until the air in the cylinder and in the dual compartment reservoir are equalized.

That said, I always assumed the brakes on most subways and light rail cars were electrically actuated...I never really hear air hissing when the brakes are applied or released.

 

[AlanB]

That said, I always assumed the brakes on most subways and light rail cars were electrically actuated...I never really hear air hissing when the brakes are applied or released.

Not sure about the DC Metro, but the NYC subway cars are air.

 

[Neil_M]

AThe WMATA cars are all lightly built. Strength can be had without excessive weight, but the car builders in Europe and elsewhere propogandize that such is not possible. Management buys into that so does not require the strength that they ought to.

Still banging that old drum? Best way to survive a crash is not have one in the first place. Anything else is just window dressing.

Yes I am, and with no apologies to anybody for doing so. These people that are trying to sell glorified tin cans as rail cars have blood on their hands as far as I am concerned.

If you think all accidents are preventable, you do not live in the world of reality.

It helps if the engineers are not busy texting people.....

You can't prevent accidents entirely but you can have more control over what happens to stop trains colliding, rather than come up with some purely random nonsense about building indestructible rail vehicles and controlling what happens in a crash.

Better see if Superman can come up with Kryptonite Railcars....

 

[jackal]

It helps if the engineers are not busy texting people.....You can't prevent accidents entirely but you can have more control over what happens to stop trains colliding, rather than come up with some purely random nonsense about building indestructible rail vehicles and controlling what happens in a crash.

Better see if Superman can come up with Kryptonite Railcars....

That's the thing, though--it's NOT nonsense. The two work in conjunction together.

 

[Ryan]

That said, I always assumed the brakes on most subways and light rail cars were electrically actuated...I never really hear air hissing when the brakes are applied or released.

Not sure about the DC Metro, but the NYC subway cars are air.

Mix of air and hydraulic here, mostly air.

 

[Neil_M]

It helps if the engineers are not busy texting people.....You can't prevent accidents entirely but you can have more control over what happens to stop trains colliding, rather than come up with some purely random nonsense about building indestructible rail vehicles and controlling what happens in a crash.

Better see if Superman can come up with Kryptonite Railcars....

That's the thing, though--it's NOT nonsense. The two work in conjunction together.

True.

To my mind that seems not to be the case in the US.

Leaning more towards one thing than the other.