Metro train runs red signal, OCC stops train before crash

[MCL1981]

http://www.nbcwashington.com/news/local ... 14931.html" onclick="window.open(this.href);return false;

A non-revenue train ran a red signal outside Smithsonian. According to the article, OCC stopped the train after it ran the signal.

Questions:
1) I assume the only way a train can run a properly functioning red signal is if it's mode 2-2 or mode 3, which cuts out ATP?
2) Is it normal for a non-revenue train to be in mode 2-2 or mode 3 on the main lines? If not, why would it be (other than operator stupidity)?
3) How does OCC stop the train??
4) I'm pleasantly surprised someone in OCC was actually paying attention.

[HiLoMo]

Trains are not allowed to run with ATP cutout on the mainline unless it is for testing purposes but then OCC would give the train an absolute block to run in (i.e. revenue service trains are prohibited from running in that section of track and are signal tracked around it). The only way I could see this happening is there was a wayside ATC equipment issue or the operator cutout ATP. If it was the latter, it would be pretty evident since the cutout switch is lead sealed and would have to broken in order to do that. I don't think OCC remotely stopped the train. I think they notified the operator and he or she stopped the train.

[MCL1981]

Mode 2-2 and Mode 3 are sealed out? How do they move around yards and such if they can't use those modes without breaking a seal??

[HiLoMo]

Mode 2-2 and Mode 3 are sealed out? How do they move around yards and such if they can't use those modes without breaking a seal??

ATP isn't cutout in the yards. When there are no wayside signals, the ATC system resorts to "stop and proceed" mode which limits the max operating speed of the train to 15 mph. ATP is only cutout for emergency and testing purposes.

Also, what do you mean by mode 2-2 and mode 3? Are you getting confused with the door mode switch?

[MCL1981]

My understanding is as follows:

Mode 1 is full automatic
Mode 2 Level 1 is manual control with all other automatic stuff working, which is what they're using now.
Mode 2 Level 2 is manual control with ATP/ATO/ATC cut out with speed limited to 15mph.
Mode 3 is manual with no protections or limiters of any kind. Push stick, train go.

I thought they used Mode 2 level 2 when not on the main lines, or when a track circuit is screwed up.

[HiLoMo]

My understanding is as follows:

Mode 1 is full automatic
Mode 2 Level 1 is manual control with all other automatic stuff working, which is what they're using now.
Mode 2 Level 2 is manual control with ATP/ATO/ATC cut out with speed limited to 15mph.
Mode 3 is manual with no protections or limiters of any kind. Push stick, train go.

I thought they used Mode 2 level 2 when not on the main lines, or when a track circuit is screwed up.

Their are three operating modes of the train - ATO (full automatic train operation), manual with ATP (operator drives train but protected by wayside signals - speed & occupied blocks), manual with ATP cutout (operator drives train and not protected by wayside signals). The first two work in conjunction with the door mode selector which has the following settings - Auto Doors Open/Auto Doors Close, Auto Doors Opening/Manual Door Close, and Manual Door Open/Manual Door Close.

[MCL1981]

Apparently the mode information I read about was wrong then. OK.

So I guess my next question is this:

How does a train go past a red signal, or any other stop indication, without breaking the seal and cutting out ATP. Can you proceed at 15mph once you've stopped? OR are you stuck there until you cut out ATP?

Assuming you can proceed after coming to a stop... I'd like to think the train operator isn't actually that stupid to forget there's a red light in front of his/her face. Which leads me to believe OCC incorrectly told the train operator to proceed, then caught their own mistake and told him to stop.

[HiLoMo]

Apparently the mode information I read about was wrong then. OK.

So I guess my next question is this:

How does a train go past a red signal, or any other stop indication, without breaking the seal and cutting out ATP. Can you proceed at 15mph once you've stopped? OR are you stuck there until you cut out ATP?

Assuming you can proceed after coming to a stop... I'd like to think the train operator isn't actually that stupid to forget there's a red light in front of his/her face. Which leads me to believe OCC incorrectly told the train operator to proceed, then caught their own mistake and told him to stop.

Yea, I am still scratching my head on how this happened. If ATP is cut in, the ATC system would not allow the train to move past a red signal since the wayside equipment should be sending a zero speed command based upon the occupied block ahead of it. I don't believe OCC can change wayside signals to allow a train to move into occupied block. All they can do is change the limiting speed on a block.

[MCL1981]

So if a block has a failed circuit giving no command at all, the lack of command allows the train to stop-and-proceed just like in the yards? If there is a valid command, and that command is zero/stop, there is no way to move past it without breaking the seal and cutting out ATP? This is very strange. It seems then that OCC would have to tell him to break the seal and proceed with ATP cut out. I find that a bit hard to believe since it would require multiple people executing multiple levels of stupidity in sequence.

Although, I suppose that train could have been intentionally operating with ATP cut out due to malfunction and heading back to the yard. And while doing so, ran the signal. The article does not say why the train was not in revenue service. Although it was closing time, so it's more likely it was just out of service and heading home.

[strench707]

How far is the furthest signal of the interlocking from the platform? 150 feet or is that a different measurement?

Can we rule out that the train stopped at the red signal and then proceeded again? I am not familiar with the territory. If you have sight on the interlocking signals, would you also have sight on the platform ahead? If so, the operator would have been seeing a lot of red lights, e.g. signal lights and marker lights of train ahead.

I would love some more detail on the territory if someone can provide.

Davis

[HiLoMo]

So if a block has a failed circuit giving no command at all, the lack of command allows the train to stop-and-proceed just like in the yards? If there is a valid command, and that command is zero/stop, there is no way to move past it without breaking the seal and cutting out ATP? This is very strange. It seems then that OCC would have to tell him to break the seal and proceed with ATP cut out. I find that a bit hard to believe since it would require multiple people executing multiple levels of stupidity in sequence.

Although, I suppose that train could have been intentionally operating with ATP cut out due to malfunction and heading back to the yard. And while doing so, ran the signal. The article does not say why the train was not in revenue service.

Okay, just got clarification from my friend who used to be an ATC engineer over there. If the train is in manual mode with ATP cut in and receives a zero speed command, the ATC system resorts to stop and proceed mode in this condition. Meaning, the operator can go past the red lunar but he or she is limited to 15 mph. However, by Standard Operating Procedures, the operator should have stopped the train because a) the lunar was red and b) the train was receiving a zero speed command.

[MCL1981]

OK. Presuming the we're not dealing with multi system failure here, the operator would have had to stop at the red signal, then could proceed past it only after stopping. If the operator didn't stop first, ATP would have stopped the train.

So, he correctly stopped, then OCC mistakenly told him to proceed, then told him to stop realizing their error? I'm having a hard time picturing a system failure that could allow this to happen by accident without human error.

[dcmike]

For clarification re: the "mode" vernacular. It's very confusing and almost never used internally except in technical documents. It has nothing to do with door modes either. The "level" distinction is a state not configured by the operator but by the wayside equipment.

Mode 1: Automatic operation with ATP.

Mode 2: Level 1: Manual operation with ATP and valid speed command received.
Mode 2: Level 2: Manual operation with ATP and no speed command being received. Normal operating mode in rail yards. Also known as SAP (stop and proceed mode). Train speed is limited to 15 MPH by ATP.

Mode 3: Manual operation with no ATP. Train is under full control of the operator with no protection.

When a train is being operated manually and closes in on another train, the wayside equipment in this block "goes silent" (does not transmit any speed command). With no speed command being received, the train is now said to be in Mode 2 Level 2. In this state, the train must immediately come to a full stop. The operating rule in the state requires the train hold its position until a speed command is received or ROCC directs otherwise. However, after making a complete stop, even when no speed command is being received, the operator may still choose to ignore the rule and drive the train at a speed of up to 15 MPH (without physically switching modes or breaking any seals). This is a red signal violation and will set off an alarm at ROCC.

Whew. So back to this incident. More than likely it was entirely the operator's fault and not any equipment malfunction. So why does this happen?

There are several spots on the railroad where speed commands drop out unexpectedly for no (apparent) reason. Operators tend to learn these locations and know that if they just creep up another 5 or 10 feet, they'll clear the dead zone and the speed commands will come back. Skilled operators may choose to take this risk if they're confident they haven't closed in on their leader or an out-of-alignment switch. The other option is sitting and waiting for a break in radio traffic and requesting clearance to proceed out of the dead zone. This can sometimes take minutes. Given the immense pressure for operators to be on schedule and the high number of known dead zones, it's not surprising operators sometimes choose to risk moving up instead.

[srepetsk]

Whew. So back to this incident. More than likely it was entirely the operator's fault and not any equipment malfunction.

That's half of it, at least.

[Sand Box John]

"dcmike"

There are several spots on the railroad where speed commands drop out unexpectedly for no (apparent) reason. Operators tend to learn these locations and know that if they just creep up another 5 or 10 feet, they'll clear the dead zone and the speed commands will come back. Skilled operators may choose to take this risk if they're confident they haven't closed in on their leader or an out-of-alignment switch. The other option is sitting and waiting for a break in radio traffic and requesting clearance to proceed out of the dead zone. This can sometimes take minutes. Given the immense pressure for operators to be on schedule and the high number of known dead zones, it's not surprising operators sometimes choose to risk moving up instead.

One could say it is WMATA's unsanctioned equivalent of NYCT's keying by.