Question about scenario in movie

[Lithonia Operator]

I asked this question in a different forum, but it really belongs over here. I was referring to the movie Unstoppable, with Denzel Washington.

At first I thought the basic premise was bogus, but then I read about the actual case.

I never dreamed that any engineer, who was the only one on the engine, would ever get off a moving train and run ahead to line a switch! Is that in any way a common practice? 

Can someone tell me why the engineer wouldn't just stop the train, then line the switch. The movie gave the impression that he couldn't stop the train (actually a yard cut, I think, with an engine), so had to run ahead. But if he could outrun the train, then it sure seems like it was going slowly enough to stop. Or was it that the engines's brake hose was not connected to the cut, and therefore the only brake available was the independent, which he knew would not suffice (I think even in the yard there was some downgrade). Did the cut maybe have "bottled air," but there was no way to initiate a train-line brake application?

What the hell would posses him to run ahead?

(For those of you not aware of the story, the engineer tripped and fell, and could not get back on the train, which then became a serious runaway. This happened in real life, and the movie was based on tat incident.)

[steve-in-kville]

Not an answer to your question, but the engineer was quite experienced and had a flawless record up until that incident. Perhaps he had done it before and never had a mishap? FYI- The locomotive was originally called Crazy 8's and the movie it was called Triple 7's or something like that.

[zugmann]

Pulling a draft of cars with no air, he probably wouldn't be able to stop it in time with just the engine brakes.  And since RR's have draconian discipline policies and lose their collective (crap) when someone runs through a switch... well... 

 

 

[BaltACD]

zugmann

Pulling a draft of cars with no air, he probably wouldn't be able to stop it in time with just the engine brakes.  And since RR's have draconian discipline policies and lose their collective (crap) when someone runs through a switch... well... 

A 4K to 6K ton track of cars easily overpowers the braking power of a locomotive even at very low speed - inertia, just keeps on moving and overcomes the braking resistance of the locomotive. 

[Convicted One]

But why leave the throttle engaged?

[adkrr64]

Convicted One

But why leave the throttle engaged?

 

 From my understading, he thought he had applied the dynamic brake lever and instead applied the throttle lever. Plausible for certain types of control stands, especially if one is in a panic.

[MMLDelete]

zugmann

Pulling a draft of cars with no air, he probably wouldn't be able to stop it in time with just the engine brakes.

I've been trying hard to learn (I read a long article last night), but railroad brakes still confuse me. I thought if a train was detached from its engine, then (unless the air was "bottled" by closing the angle cock) all the train brakes in effect "go into emergency:" the train line suddenly unloads its air, so then the reservoirs apply all the brakes.

Are you telling me that when the air rushes out with the big pfffffffft, that's not just air from the brake pipe, but rather it's also from all the reservoirs?

[tree68]

Lithonia Operator

Are you telling me that when the air rushes out with the big pfffffffft, that's not just air from the brake pipe, but rather it's also from all the reservoirs?

A good read on this would be Al Krug's primer on air brakes:

http://www.railway-technical.com/trains/rolling-stock-index-l/train-equipment/brakes/north-american-freight.html

 

[zugmann]

adkrr64

 

 

Convicted One

But why leave the throttle engaged?

 

 

 

 

 From my understading, he thought he had applied the dynamic brake lever and instead applied the throttle lever. Plausible for certain types of control stands, especially if one is in a panic.

 

Forgot about that. Engine had the power/dynamic selector switch. 

[mudchicken]

In recent memory, CSX had an issue in north central Ohio with a similar scenario with an engine and GP30 slug going for a ride.

[MMLDelete]

tree68

 

 

Lithonia Operator

Are you telling me that when the air rushes out with the big pfffffffft, that's not just air from the brake pipe, but rather it's also from all the reservoirs?

 

 

A good read on this would be Al Krug's primer on air brakes:

http://www.railway-technical.com/trains/rolling-stock-index-l/train-equipment/brakes/north-american-freight.html

 

 

That's exactly the article I read last night!  I must have misunderstood.

Yes or No: when the hose gets disconnected from the engine, it also dumps all the air from the reservoirs in the train?

 

[CShaveRR]

Lithonia Operator

Yes or No: when the hose gets disconnected from the engine, it also dumps all the air from the reservoirs in the train? 

Only if there were air in the reservoirs to begin with.  This was a yard move, and the cars probably had all been bled off, hence were just that much rolling weight.

Back when we were tying onto a track in the classification yard to couple and pull it, we'd make the hoses and cut the air in on the first three or four (or so) cars, to give the poor overused Geep a little extra stopping power.

[tree68]

Lithonia Operator

Yes or No: when the hose gets disconnected from the engine, it also dumps all the air from the reservoirs in the train?

No.  Key phrase there is "all the air."  

With an emergency application (brake pipe pressure suddenly goes to zero), air from the reservoirs is routed to the brake cylinders.  The pressure in the reservoirs will only drop to a certain point, that being where the pressure in the reservoir equalizes with that in the brake cylinders.  That's what holds the brakes in application.  There will still be pressure in the reservoirs, hence my "no" answer.

As you saw in the primer, when air pressure is restored to the brake line, the reservoirs recharge and the pressure in the brake cylinders is released to the atmosphere, releasing the brakes.  But I digress.

In the case of work in a yard, it's necessary to release all pressure (bleed off) from the reservoirs as well, so there's no way for the brakes to apply.  This is why it takes so long to completely charge a train - if all the cars have been bled off then all the reservoirs have to be refilled.  That can be a lot of air.

If the brake system air on a car is good and tight, an emergency application such as will occur when a car is set out and the air is thus dumped  may hold for quite a while. A "leaky" car may only hold that application for a short while.  

Hopefully the mud has settled a little...

 

[SD70Dude]

zugmann

adkrr64

Convicted One

But why leave the throttle engaged?

 From my understading, he thought he had applied the dynamic brake lever and instead applied the throttle lever. Plausible for certain types of control stands, especially if one is in a panic.

Forgot about that. Engine had the power/dynamic selector switch. 

Yes.  

Here is a control stand with a single controller handle and the selector switch, which determines whether the controller handle will engage traction power or dynamic braking.

https://en.m.wikipedia.org/wiki/File:UP_Centennial_control_stand.jpg

Here is a control stand with separate throttle and dynamic handles:

https://www.discoverlivesteam.com/discoverforsale/forsale/8_Flanders/IMG_8243.jpeg

[Paul of Covington]

   I remember reading about this incident in TRAINS, and I've wondered ever since why the engineer would consider putting the engine in dynamic braking.  It's my understanding that dynamics are ineffective at low speed (at least in DC locomotives), and since he was engaged in yard work, I wouldn't have thought that he would consider it.

[MMLDelete]

tree68

 

 

Lithonia Operator

Yes or No: when the hose gets disconnected from the engine, it also dumps all the air from the reservoirs in the train?

 

 

No.  Key phrase there is "all the air."  

With an emergency application (brake pipe pressure suddenly goes to zero), air from the reservoirs is routed to the brake cylinders.  The pressure in the reservoirs will only drop to a certain point, that being where the pressure in the reservoir equalizes with that in the brake cylinders.  That's what holds the brakes in application.  There will still be pressure in the reservoirs, hence my "no" answer.

As you saw in the primer, when air pressure is restored to the brake line, the reservoirs recharge and the pressure in the brake cylinders is released to the atmosphere, releasing the brakes.  But I digress.

In the case of work in a yard, it's necessary to release all pressure (bleed off) from the reservoirs as well, so there's no way for the brakes to apply.  This is why it takes so long to completely charge a train - if all the cars have been bled off then all the reservoirs have to be refilled.  That can be a lot of air.

If the brake system air on a car is good and tight, an emergency application such as will occur when a car is set out and the air is thus dumped  may hold for quite a while. A "leaky" car may only hold that application for a short while.  

Hopefully the mud has settled a little... 

Thanks, Larry.

So, say a train comes off the road, into a yard. The power unhooks, heads off to the engine house. The cut now has air in the reservoirs and in the cylinders, the amount of which a result of how much braking and re-charging had been done on the road.

So, do the car-knockers now walk the train and 1) check for defects, and 2) bleed all air from the cylinders and reservoirs?

Does a single valve bleed both the car's cylinder and reservoir? Is there any way to bleed more than one car at a time? Is there a situation whereby the cylinders get bled, but some air is retained in the reservoirs? If so, why would one do that?

Did the train crew tie on some hand brakes on the cut before they disconnected?

Is "bottling air"which I know is against the rules, a way for an engine crew to disconnect from the cut and, say, go pick up a car in a stub track, then couple back up up, but not have to use all time pumping the train back up? Is that why you'd bottle air.

Please answer like you're teaching a sixth-grader! 

[tree68]

Lithonia Operator

So, do the car-knockers now walk the train and 1) check for defects, and 2) bleed all air from the cylinders and reservoirs?

Not something I have any experience with - in fact, we can't move passenger cars unless they are on air.

Lithonia Operator

Did the train crew tie on some hand brakes on the cut before they disconnected?

Absolutely.  Have mercy on their souls if they don't and the cut rolls away.  The employee timetable will have specific guidelines for how many brakes need to be set - and that's a minimum.  The actual number is however many are needed to hold the cars from movement.

Lithonia Operator

Is "bottling air"which I know is against the rules, a way for an engine crew to disconnect from the cut and, say, go pick up a car in a stub track, then couple back up up, but not have to use all time pumping the train back up? Is that why you'd bottle air.

Don't get caught!  While a crew could use that practice, you won't find it in the field.  The dispatcher has the delay planned in his/her plan.  Doing so for an "early quit" might result in a permanent quit...

[BaltACD]

Lithonia Operator

So, say a train comes off the road, into a yard. The power unhooks, heads off to the engine house. The cut now has air in the reservoirs and in the cylinders, the amount of which a result of how much braking and re-charging had been done on the road.

So, do the car-knockers now walk the train and 1) check for defects, and 2) bleed all air from the cylinders and reservoirs?

Does a single valve bleed both the car's cylinder and reservoir? Is there any way to bleed more than one car at a time? Is there a situation whereby the cylinders get bled, but some air is retained in the reservoirs? If so, why would one do that?

Did the train crew tie on some hand brakes on the cut before they disconnected?

Is "bottling air"which I know is against the rules, a way for an engine crew to disconnect from the cut and, say, go pick up a car in a stub track, then couple back up up, but not have to use all time pumping the train back up? Is that why you'd bottle air.

Please answer like you're teaching a sixth-grader! 

If the terminal is a Hump Yard and the arriving train is to be switched over the hump as its 'next' move, the car inspectors will perform a arrival inspection of all cars and bleed the air off the reservoirs so the cars can be 'free wheeling' over the hump.  The single bleed rod can be activated from either side of the car.  The inspection also identifies defects that may cause car(s) to be switched for Shop Track attention.  Each Hump Yard has its own set of TTSI on how the first cars switched into a Bowl Track are to be handled - if hand brakes are to be used, if skates are to be used, if the configuration of the Bowl Track percludes a free rolling car from exiting the track (many Bowl Track are built with the configuration of a bowl - higher on both ends of the track than at the middle of the tracks length.

TTSI for the Terminal will govern the application of hand brakes for arriving trains; not all Terminals have the same TTSI because of the differing 'lay of the land' for each terminal.

The couple of minutes 'saved' when the air is bottled on a cut of cars does not come close to equaling the risk of the cut releasing the air and rolling away.  A simple risk/reward equation.  Anecdote - CSX coal train moving from Brunswick, MD to the Pepco Morgantown Power Plant via Benning Yard in the District of Columbia.  Trains arriving Benning from Brunswick are moving West to East,  trains departing Benning for Morgantown require the EOT and Power to be in the opposite positions that they arrived from Brunswick.  Crew from Brunswick brought a train into Benning, made a reduction on the train an bottled the air as they went to the rear of their train to get the EOT and bring it back to where the power HAD been coupled.  Before they could get the EOT and return to where they were previously coupled - the train ran away onto the Anacostia River Bridge (that was undergoing reconstruction accound steel eating bacteria in the river had damaged the original bridge) the bridge collapsed under the weight of the cars and about 19 cars ended up in the river.  Risk/reward. 

[MMLDelete]

BaltACD

The couple of minutes 'saved' when the air is bottled on a cut of cars does not come close to equaling the risk of the cut releasing the air and rolling away.

If the cut released the air, wouldn't that make the brakes apply? And keep the cut from moving?

I thought the problem with bottled air is that it keeps the brakes in the released position. So if enough hand brakes aren't set, there ... goes ... your ... train ...

[tree68]

Lithonia Operator

I thought the problem with bottled air is that it keeps the brakes in the released position. So if enough hand brakes aren't set, there ... goes ... your ... train ...

The air could (and probably would be) bottled with a set on the train, and this is where the problem lies.  

If a leak allows air back into the brake pipe the increase in pressure in the bottled line will likely cause the brakes on the cars to release (as noted in the primer).  

On top of that, modern brakes are designed so that air from the emergency reservoir is also fed into the brake pipe, speeding the release of the brakes.

IF you're going to not set hand brakes, you're better off not bottling the air, as the emergency application is going to hold for a while, anyhow.

[mvlandsw]

Paul of Covington

   I remember reading about this incident in TRAINS, and I've wondered ever since why the engineer would consider putting the engine in dynamic braking.  It's my understanding that dynamics are ineffective at low speed (at least in DC locomotives), and since he was engaged in yard work, I wouldn't have thought that he would consider it.

 

CSX had/has some four axle locomotives with only one brakeshoe per wheel. These do not have the braking power of units with two brakeshoes per wheel. When I would kick cars using one of the one shoe per wheel units it would not stop very well. I would put the independent brake on and put the dynamic into the full application position. Although the dynamic would not provide much braking it did add a little more than just the independent brake, especially if it had extended range dynamics which provide more output at low speeds.

If the wheels were to slide the wheel slip system would operate to give warning and cut off the dynamics. You would get no such warning using just the independent brake.

Mark Vinski

[zugmann]

mvlandsw

If the wheels were to slide the wheel slip system would operate to give warning and cut off the dynamics. You would get no such warning using just the independent brake.

Except for the unmistakable ssssssssssss.... from under the cab. 

 

For us, we are prohibited from using the dynamic and indep together.  It's a trigger that will get emailed to whatever roadforemen are left.  I've done plenty of shifting with single brakeshoe engines - some times you have to be the mean engineer and tell Mr. Conductor to give you a couple cars of air. 

[BaltACD]

Lithonia Operator

 

BaltACD

The couple of minutes 'saved' when the air is bottled on a cut of cars does not come close to equaling the risk of the cut releasing the air and rolling away. 

If the cut released the air, wouldn't that make the brakes apply? And keep the cut from moving?

I thought the problem with bottled air is that it keeps the brakes in the released position. So if enough hand brakes aren't set, there ... goes ... your ... train ...

When brakes are applied, air is taken out of the train line and thus signaling the brake valve for the higher pressure in the reservoir to apply the pistion in the brake cylinder.  If the air is bottled you now have a captive trainline - IF a defective brake valve for whatever the reason vents either its service or emergency brake reservoirs into the train line - the train line pressure increases thus signaling all the brake valves in the trainline to release their brakes.  With the brakes having been commanded to release - away rolls the train.

If you cut away from a train, vent the trainline to atmosphere!

[zugmann]

BaltACD

If you cut away from a train, vent the trainline to atmosphere!

Well, you should have proper handbrakes witha proper handbrake test, so the air shoudn't matter.  

[cx500]

I understood one cause was closing the angle cock while the train line was still venting, which could cause enough of a "bounceback" in the air column to fool the valves into thinking it was a release.  I may be wrong.

[SD70Dude]

cx500

I understood one cause was closing the angle cock while the train line was still venting, which could cause enough of a "bounceback" in the air column to fool the valves into thinking it was a release.  I may be wrong.

That's right.  When we 'cut and vent' the Engineer has to wait for the exhaust to cease before telling the Conductor to close both angle cocks, uncouple the locomotive, and then slowly open the angle cock on the train.

The "Quick Release" feature of modern car control valves is the main cause of unintentional releases when the air is bottled.  This feature works by pouring air from the car's emergency reservoir back into the brake pipe when the triple valve moves to the release position.

Let's say we have bottled the air on a train, and one car has a air leak on the control valve or auxiliary reservoir pipe.  Once the auxiliary reservoir pressure drops below the brake pipe pressure the triple valve will move to the release position, and the emergency reservoir air (still at a full charge of 90 PSI) will be allowed into the brake pipe, raising the brake pipe pressure at that car.  Once this rise in pressure reaches the next car it will also release, and this process will continue until most, if not all the cars are released.

Of course, the train may roll away and derail before every single car is released.

[Paul of Covington]

SD70Dude

The "Quick Release" feature of modern car control valves is the main cause of unintentional releases when the air is bottled. This feature works by pouring air from the car's emergency reservoir back into the brake pipe when the triple valve moves to the release position. Let's say we have bottled the air on a train, and one car has a air leak on the control valve or auxiliary reservoir pipe. Once the auxiliary reservoir pressure drops below the brake pipe pressure the triple valve will move to the release position, and the emergency reservoir air (still at a full charge of 90 PSI) will be allowed into the brake pipe, raising the brake pipe pressure at that car. Once this rise in pressure reaches the next car it will also release, and this process will continue until most, if not all the cars are released.

   I remember when I first read about that, I found it hard to believe.  It seemed incredibly dangerous.  It seems like a minor fault can release all the brakes.  If you sense that this is happening, is it likely that you can dump the air and have enough air in the reservoirs to stop the train?  Have any of you engineers had this happen?

  (edit) I realized after I wrote the above that you were talking about the air being bottled, but if it happens when you are moving (say downhill) with a service application on, won't the same problem exist?

[BaltACD]

Paul of Covington

   I remember when I first read about that, I found it hard to believe.  It seemed incredibly dangerous.  It seems like a minor fault can release all the brakes.  If you sense that this is happening, is it likely that you can dump the air and have enough air in the reservoirs to stop the train?  Have any of you engineers had this happen?

  (edit) I realized after I wrote the above that you were talking about the air being bottled, but if it happens when you are moving (say downhill) with a service application on, won't the same problem exist?

Engines of recent vintage (last half century) have a Pressure Mainting feature that will keep the trainline pressure at the pressure set by the Engineer when he made his brake line reduction to apply the brakes.

In the bottled air 'release' the only air pressure entered into the trainline comes from the defective brake valve's reservior, which changes the pressure in the trainline.

[Paul of Covington]

   OK, I see the difference.  The maintaining feature will bleed off the air that was added by the defective valve.  Thanks.  I guess it's not as bad as I thought.

[MMLDelete]

tree68

The air could (and probably would be) bottled with a set on the train, and this is where the problem lies.

Larry, I think I've pretty much got it, but could you explain the above part more?

Sorry to be so numb.