Classic British Flight Sim

As I work for a US railroad.....

Yes, the sound your hear is the air pipe breaking and thus the full emergency brake application being applied. As was alluded to, while the brakes on the entire train are applied, one must consider that the entire trailing consist still on the rail, while the brakes are applied, is much heavier than the 2 or 3 locomotives in the consist (I've not found the report, but I believe I was told there were 2 locomotives on the train). As such, basic inertia comes into play and thus the brakes are able to bring the locomotives to a stop much faster than the trailing cars.

As the crew was probably hunkered down under their control stands, they probably weren't thinking about overriding the emergency brake application to move forward and clear of the oncoming rear portion of the train.

The US is currently moving to electronic braking systems to suppliment the air brakes. This system uses a wire running parallel to the air hoses that allows for faster activation of the brakes in both normal and emergency situations by electrically actuating the brake valve on each car individually (and thus simultaneously) instead of relying on the air reduction of the main pipe (which travels at approx. 2000 feet per second if I remember correctly) to cause the application.

I knew Chris would have the answer to this -- I'm just in awe of the force that can throw rail cars around with impunity like that -- Im also curious as to the contents of the first tank car -- at least it didnt go BOOM with all those sparks flying around


Leif

Never been through a tornado myself (never hope to be too) but I'm completely awestruck seeing them on tv. Last spring an EF5 (as big and bad as they come) rolled through a town in the northeastern part of Iowa. The security camera on a drive-up ATM caught this:

http://www.youtube.com/watch?v=lAPnbzHvIKs

I still get chills when I watch it.

Chris

amazing bit of video --- Chris you live in Iowa and havnt seen one?? amazing

I sit and watch the level 4-5 stuff on radar all day and it scares the beejesus out of me and Im 1000 miles from the action!!!

I was going to ask Joe (Airboatr) if he saw the one reported at West Palm last week -- (for the folks on THAT side of the pond)

Florida usually gets water spouts NOT Tornados


Leif

We've had quite a few in the Denver area recently, including one, that we're pretty sure went right over our house, but didn't touch down. It was just enough that the leaves and grass clippings spiraled up and away, but no other damage, or anything else missing. About a mile away, it damaged some stores, and took down power lines in a dozen places.

Oooer. EF5 Tornado, eh? I'd never heard of that before, but I'm pretty sure I don't ever want to meet one!

We're so lucky in the UK to live in a temperate climate (although you wouldn't think it to hear people complain abot the weather!). Unless you're one of the unfortunate or unwise people who live on a flood plain there aren't any extremes of weather to worry about when you go to bed. The worst that's ever likely to happen is wet feet or a ridge tile blown off.

How on earth do you guys who live in a climate of such extremes cope with the thought that a natural disaster could take away your home at short notice? Do you have a cellar full of survival equipment - or just hope?

Chris - thanks for the explanation about the braking system and the reason for the rear part of the consist catching the slowing locomotives. That makes a lot of sense.

Now - while we're in the mood - how about this one? An in-cab video of a head-on collision between two freight trains in 2006. The points are set for our locomotive to go into the passing loop so the oncoming loco shouldn't be there. But our signals appear to be red. I'm not familiar with US signalling procedures but it looks like it could be a signalling error or fault. How about it, Chris?

http://www.metacafe.com/watch/717099/train_crash/

Ian

speedbird591 wrote:How on earth do you guys who live in a climate of such extremes cope with the thought that a natural disaster could take away your home at short notice? Do you have a cellar full of survival equipment - or just hope?

No, we pray. Hope is for guys from Arkansas and Chicago.... Their names are Bill and Barak. Odd how they both start with B...

Now - while we're in the mood - how about this one? An in-cab video of a head-on collision between two freight trains in 2006. The points are set for our locomotive to go into the passing loop so the oncoming loco shouldn't be there. But our signals appear to be red. I'm not familiar with US signalling procedures but it looks like it could be a signalling error or fault. How about it, Chris?

http://www.youtube.com/watch?v=Mus8xOs2rWk

Ian

This is a classic accident that has been shown all over the industry because it typifies why we make sure to read back dispatcher instructions. If you watch the video, you will see that the first signal shows "Approach Medium". This means that you slow the train to 35 MPH and be prepared to stop at the 2nd signal you come to (not the next one). Per previous radio communications between the 2 train crews and a dispatcher, the BNSF train that we are on is supposed to enter the siding and go around the oncoming train. The oncoming train is to stop short of the switch. The second signal (go to 0:39 for a clear look) shows a "Diverging Clear" which means that the switch has been thrown to take the train into the siding and the track beyond the signal is clear. 1 second later (0:40), the signal is "thrown in the face" of the engineer as the approaching BNSF train fails to stop as it is supposed to. The signal changes from "Diverging Clear" to "Stop" meaning that the oncoming train has not stopped and is now "fouling" the clearance zone and there will be a collision if the trains don't stop quickly. At 0:42, you see the engineer of the oncoming train jump off the locomotive. Shortly thereafter (obscured by the engine) the conductor jumps off. The train we're riding on, the 3 crewmembers stay onboard to "ride out" the collision. The impact speed was 52 mph. Thankfully everyone survived although several were very badly hurt.

The US signals can be complex, but in basic, the top light of a signal is green and means "clear" or go. The middle light is yellow and means "caution" or be prepared to stop. The bottom light is red and means "stop" or the way ahead is not clear. When there are more than 1 route possible, you stack multiple signals atop each other. The top signal will be for the mainline and each signal below will be for the diverging routes available. So when you see a red over green, that means that straight ahead is blocked (either by switch position or by train occupancy) and the route that diverges is clear. When you see 2 yellows, that means that you need to be ready to stop because neither way may be clear. When you see 2 reds, it means that no route is clear and you must stop before the signal to ensure safety. More information if you're interested - http://www.lundsten.dk/us_signaling/

Chris Trott wrote:The US signals can be complex ...

You're not kidding, Chris! I've had a look at the link you gave and am now completely bewildered. Fortunately the British signalling system is much easier to understand - which is just as well as I'm tested on it every two years!

Thank you for your explanation of the video. I can understand it better now. So it would seem that, if the stop signal for the oncoming train was at red then the engineer has passed it at danger. What we call a SPAD (signal passed at danger). Do you not have a protection system that applies the train brakes automatically in a situation like that? Although I would hope that the approaching train must have had emergency braking applied yet still had plenty of momentum when it reached the switch :think:

Ian

Yeah, you can hear them put the train in Emergency when the signal goes red, but nothing would have prevented the accident, even Automatic Train Stop (which is what the system is called). The oncoming train was still doing 22 MPH when he blew through the red and was over 8000 trailing tons, so even with the train in Emergency, it would have taken close to a quarter mile to stop. The train the camera was on was doing 30 MPH and was over 10,000 trailing tons (that's US tons - 2000 lbs/each) and probably would have taken well over half a mile to stop. The only thing that would have prevented the accident would have been for the oncoming engineer to follow his warrants and the signals he saw, which he didn't.

The "searchlight" system, which is what that link discusses primarily is very simple in execution in reality. Remember, you only have 3 lights per signal and each light can only display 3 indications - lit, flashing, or steady. If you look here - http://www.lundsten.dk/us_signaling/asp ... index.html , it shows the chart of the signal indications that apply to the accident. If you understand that each indication gives a certain aspect (i.e. meaning), you can get a lot of information from a very limited system. The theory behind how the Absolute Block System and its more sophisticated brethren is complex, but remember that as a train crew, you're only looking at one signal at a time. Knowing the theory helps you anticipate what is next, but all the information needed to safely operate the train is presented on the signal in front of you. ABS is an extremely resilient and simple system to operate. The only more complex you get is in what's called DTC territory where you have a dispatcher who has the ability to set switches and place a "lock out" on signals. The signals operate according to the ABS rules in this system, but the dispatcher has the ability to turn any signal red. They cannot specify any other indication than red. So when a dispatcher removes his "block" from a signal (i.e. he's no longer telling it to show red), then the signal is returned to ABS control and will indicate whatever the ABS system says it should. Thus, all a dispatcher can do is make the system safer. He cannot set the signals in a condition where opposing trains would both see green signals.

speedbird591 wrote: http://www.youtube.com/watch?v=Mus8xOs2rWk

Ian

The compooter sez NO! :@
"This video is no longer available due to a copyright claim by BNSF Railway Company"

Bob