Push Pull

Discussion relating to the operations of MTA MetroNorth Railroad including west of Hudson operations and discussion of CtDOT sponsored rail operations such as Shore Line East and the Springfield to New Haven Hartford Line

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s4ny
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Push Pull

Post by s4ny » Sun Dec 01, 2013 12:43 pm

I have already been called an idiot by another member on another topic on this forum, but when I look at
the pictures of the tragic accident this morning on the Hudson Line, I think that this
would have been less severe if the locomotive had been pulling the train.

Pushing passenger cars will certainly be studied as a possible exacerbating factor
in this horrible accident.

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Tommy Meehan
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Re: Push Pull

Post by Tommy Meehan » Sun Dec 01, 2013 1:14 pm

First of all you're right, no one should resort to namecalling. Don't let it bother you, that says more about them than you.

Second, you're timing in bringing this up is pretty bad. It just happened. People don't really want to deal with this right now. Why? Because you don't know what happened -- at this point no one really does -- and to blame the use of push/pull operation is premature. Railroads have been using push/pull commuter trains for over fifty years and it has been proven to be a safe operation.

In this instance yes, it's possible if the locomotive was leading maybe the causalities would've been reduced. You could say the same thing if the first car had been closed to passengers. If the accident had involved colliding with another train having the locomotive leading might've made it worse.

About seventeen years ago there was a collision between a MARC train and an Amtrak train on CSX at Silver Spring Maryland. The MARC train was operating cab car first. One of the brotherhoods made a complaint about it, alleging it wasn't safe. The NTSB found that not to be the case. There was nothing inherently dangerous about operating with cab cars. The NTSB made the point I made earlier. In some circumstances having a cab car leading might cause additional casualties. But that is a result of the circumstances of a particular accident. It's not the result of an inherent safety issue with cab cars. NTSB got regulations passed beefing up the crashworthiness of cab cars. The cab car in this morning's derailment seems to have remained intact and the engineer survived.

Anything else is just speculation.

DutchRailnut
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Re: Push Pull

Post by DutchRailnut » Sun Dec 01, 2013 1:23 pm

If push -pull were not safe, how come world wide over 35 000 trains a day are operated in this mode ??
experts in rail industry and with NTSB have done testing, showing absolutely no negative effect of locomotive on rear.
If Conductors are in charge, why are they promoted to be Engineer???

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Jeff Smith
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Re: Push Pull

Post by Jeff Smith » Sun Dec 01, 2013 2:55 pm

Kevin did say in the other thread that there should be separate threads for topics like push-pull, and I thank you for complying. I believe we've had the discussion before. I don't know enough about the engineering/physics of it to speak to this topic as far as likelihood of a derailment based on push vs. pull.

However, in the case of a collision, which this easily could have been had the train derailed a few more feet down the line (the station "bulkhead" is not very far), or say a tree or abutment alongside the right of way (lucky this area is basically marsh/shore) involves crumple zones. Unless you close the cab car, or convert it to a cabbage, which isn't really necessary on a commuter line, then you do have a safety issue IMHO. Of course, the same could be said for EMU's.
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Port Jervis
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Re: Push Pull

Post by Port Jervis » Sun Dec 01, 2013 5:26 pm

s4ny wrote:I have already been called an idiot by another member on another topic on this forum, but when I look at
the pictures of the tragic accident this morning on the Hudson Line, I think that this
would have been less severe if the locomotive had been pulling the train.

Pushing passenger cars will certainly be studied as a possible exacerbating factor
in this horrible accident.


Without push/pull none of the area commuter railroads could operate at the levels they do. In fact, I doubt MNCR has any capability to wye a locomotive at any of it's diesel terminals. Push/pull trains have proven themselves for half a century.
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Head-end View
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Re: Push Pull

Post by Head-end View » Sun Dec 01, 2013 6:49 pm

This morning I heard an NBC-4 TV reporter make the comment that because the locomotive was pushing the train from the rear, that there was "no way to slow or stop the train". I was so incensed by this irresponsible statement that a half-hour later I called the NBC-4 newsroom using the 800 number on their website. As soon as I told the young lady who answered the phone what I was calling about, she said they were correcting the error and hung-up on me. So I assume they had already gotten other comments about the reporter's incorrect statement. These people call themselves college educated journalists?

BTW, lead cab-car was number 6222, and the locomotive was #225.

Patrick Boylan
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Re: Push Pull

Post by Patrick Boylan » Sun Dec 01, 2013 8:50 pm

I've often wondered if pushing was more dangerous than pulling. Others have posted that "everybody does it", which I don't think answers the question of if it's dangerous or not, certainly doesn't answer the question of if it's more dangerous than pulling. Of course I also believe that automobiles are incredibly dangerous, and am not willing to feel they're less dangerous because billions of people use them every day.

My concerns about pushing have been that I expect heavy locomotive on the rear might keep pushing when it's not supposed to, as one of the reports I've read said kind of hints
http://usnews.nbcnews.com/_news/2013/12 ... in-ny?lite
Sources told NBC News late Sunday afternoon that the train's engineer — a "respected veteran" with 20 years of Metro-North experience who suffered minor injuries — claimed when first responders arrived that he hit the brakes as the train approached the turn.

If he was going from 70mph to 30 mph territory he sure should have hit the brakes, that should be normal. With locomotive on the front there are just a lot fewer connections between the control stand and the locomotive, and a lot fewer places where something could go wrong. It's obvious to me that speed was a factor. Based on the photos I've seen I can't figure anything else that would leave the track, especially the inside rail, relatively undamaged and have so many jacknifed cars, and locomotive derailed. Whether the excessive speed here was the engineer's fault, highly doubtful to me, after all these guys go over the same track several times a week, and several times a day usually, so I expect the 30mph curve shouldn't have been a surprise. Or was it technical, a one in many thousands fluke that kept the locomotive from reading the cab car's brake control, yet still kept the locomotive from applying the brakes on its own, the standard fail safe 'emergency' application that's supposed to happen when something breaks?

Slightly less plausible to me is a track problem, for which I'd expect to see a lot more rails out of place, like I saw in the New Haven line mu derailment and sidewipe.

I'm also interested in hearing how the train's brakes performed before the crash. Did it have any problems stopping at its scheduled 6 stations?

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Re: Push Pull

Post by DutchRailnut » Sun Dec 01, 2013 9:01 pm

The real experts seem to believe push-pull is safe, as today 35 000 trains a day are operated this way and testing by international agencies and domestic NTSB do seem to suggest that push-pull is safe.
only non-experts seem to think its un-safe !!
If Conductors are in charge, why are they promoted to be Engineer???

Retired Triebfahrzeugführer. I am not a moderator.

NH2060
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Re: Push Pull

Post by NH2060 » Sun Dec 01, 2013 9:10 pm

s4ny wrote:I have already been called an idiot by another member on another topic on this forum, but when I look at
the pictures of the tragic accident this morning on the Hudson Line, I think that this
would have been less severe if the locomotive had been pulling the train.

Pushing passenger cars will certainly be studied as a possible exacerbating factor
in this horrible accident.

Like what the others have said DO NOT take comments like that personally. Such language is immature to say the least.

And don't think that no one else has asked that question with great sincerity. I myself have wondered about it quite often. Let's face it a heavy locomotive pushing a set of lighter weight coaches sounds -to the average person, even a rail fan- like an accident waiting to happen. There was even a report on.. I think it was Nightline many years back about the safety and/or possible hazards of push-pull operation; this was several months after the Glendale, CA Metrolink crash.

At the same time however, having the train run locomotive-first doesn't mean it'll always end well in an accident. One example was the Chatsworth, CA Metrolink head-on collision. The force of the engines on the point of the UP freight was so great that they literally pushed the Metrolink engine into the first coach of the train.

Would the outcome have been as bad if there was a loco on the point instead of a cab car? I doubt greatly it would've made the fatality and injured count any worse or better. The force of the train flipping off the track and hitting the ground at such great a speed (resulting in passengers being thrown from the train itself when the windows smashed) was -from what I see- by far more of a culprit casualty-wise.

SlackControl
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Re: Push Pull

Post by SlackControl » Sun Dec 01, 2013 9:45 pm

Patrick Boylan wrote:I've often wondered if pushing was more dangerous than pulling. Others have posted that "everybody does it", which I don't think answers the question of if it's dangerous or not, certainly doesn't answer the question of if it's more dangerous than pulling. Of course I also believe that automobiles are incredibly dangerous, and am not willing to feel they're less dangerous because billions of people use them every day.

My concerns about pushing have been that I expect heavy locomotive on the rear might keep pushing when it's not supposed to, as one of the reports I've read said kind of hints
http://usnews.nbcnews.com/_news/2013/12 ... in-ny?lite
Sources told NBC News late Sunday afternoon that the train's engineer — a "respected veteran" with 20 years of Metro-North experience who suffered minor injuries — claimed when first responders arrived that he hit the brakes as the train approached the turn.

If he was going from 70mph to 30 mph territory he sure should have hit the brakes, that should be normal. With locomotive on the front there are just a lot fewer connections between the control stand and the locomotive, and a lot fewer places where something could go wrong. It's obvious to me that speed was a factor. Based on the photos I've seen I can't figure anything else that would leave the track, especially the inside rail, relatively undamaged and have so many jacknifed cars, and locomotive derailed. Whether the excessive speed here was the engineer's fault, highly doubtful to me, after all these guys go over the same track several times a week, and several times a day usually, so I expect the 30mph curve shouldn't have been a surprise. Or was it technical, a one in many thousands fluke that kept the locomotive from reading the cab car's brake control, yet still kept the locomotive from applying the brakes on its own, the standard fail safe 'emergency' application that's supposed to happen when something breaks?

Slightly less plausible to me is a track problem, for which I'd expect to see a lot more rails out of place, like I saw in the New Haven line mu derailment and sidewipe.

I'm also interested in hearing how the train's brakes performed before the crash. Did it have any problems stopping at its scheduled 6 stations?



When operating from the cab car, the controls in the cab car strictly control the power (throttle position and reversor direction), not the brakes. The air for the brake system is supplied by the engine, but the bake valve in the control car is what reduces the brake pipe pressure, thus applying the brakes throughout the train.

SlackControl
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Re: Push Pull

Post by SlackControl » Sun Dec 01, 2013 10:05 pm

While this topic brings up some interesting points about push-pull operation, I'd like to address a concern of mine and see what opinions people have. For a long time, I've been concerned about the types of couplers used by railroads to couple passenger equipment.

Here is a picture of two standard automatic couplers coupled. Notice that they do not have the prongs and funnels as the passenger couplers do. If a situation light a high/low or a derailment occurred, one coupler would lift out of the other one, the train would separate, but the leading car would then not pull the other cars off with it. While I understand that these coulers prevent passenger cars from separating while a passenger is walking between cars of a moving train, the consequences of having one car derail and drag the rest of a train off with it seem a lot more severe to me.

http://pianoaddict.com/wp-content/uploa ... ng-web.jpg

http://upload.wikimedia.org/wikipedia/c ... nd.agr.jpg
http://www.amstedrail.com/amstedrail/si ... oupler.jpg
Notice in the second two images, the prong one one side, and the funnel on the other side of this coupler.

Look at a majority of the accidents involving passenger trains. If one car derails, it takes the others with it. Looks like the same thing happened here too, in the Bronx today.

MBTA1016
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Re: Push Pull

Post by MBTA1016 » Sun Dec 01, 2013 10:16 pm

I'm just giving my $.02 here. With push-pull there are downsides like everything else. No system is 100% perfect, but I will say that method of running commuter trains has worked and has worked well. I'm not an engineer but I would take being in a loco before hitting something above a cab car anyday.

I got one example where having the loco on the end of a train in a crash proved useful. I think it was the 80's or 90's and an Amtrak train slammed into the loco of a stopped inbound mbta train that was in push mode at back bay station.(mbta runs push-pull) The mbta loco was totaled but no one was killed(i think). If the mbta train was oriented differently god knows how many would've been killed.
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Tadman
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Re: Push Pull

Post by Tadman » Sun Dec 01, 2013 10:16 pm

Let's think about the physics here - a train going through a slow zone with too much speed is going to derail, engine in front or back. It's also going to do some nasty damage either way, as the train weighs the same and the speed is the same. Once a hose parts or the air is manually dumped, it goes into emergency either way, it'd be pretty hard for the engine to keep pushing. I'm not sure if there's a fail-safe control wherein the engine throttles back if it loses signal from a cut-in control stand, but it wouldn't surprise me.

So the only thing left is the "battering ram" effect of having the engine in front to move an opposing train or building out of the way, and Chatsworth showed that to be of little value because the engine telescoped the front coach. Really the only advantage I've heard of is in case of a grade crossing incident, it protects the engineer better when striking a Honda.

Backshophoss
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Re: Push Pull

Post by Backshophoss » Sun Dec 01, 2013 10:33 pm

In general,The weakest link is the air brake connections and the MU jumpers between the cars and from car to loco, all it takes is
a bad hose or jumper to fail. The same is true to EMU's if the electric head fails or air connection in the head fails.

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Re: Push Pull

Post by Chicagorail1 » Mon Dec 02, 2013 1:51 am

When a train goes into emergency, it opens the pcs valve in the locomotive reducing the power to idle.
Conductors are in Charge! Thats why we got the "belt pack" and the engineers got the street!!!

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