OT: Push v. pull commuter trains

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On 12/3/13 1:41 PM, snipped-for-privacy@attt.bizz wrote:

No.
The diesel is not switched to "electric mode" until entering the Park Avenue tunnel at 97th Street.
Even then, after changeover the diesel is typically still "left running" (although not supplying traction power) until closing in on the platforms.
There are good reasons for this. A third rail shoe might get knocked off, or if the train stops with the engine "gapped" (not touching the third rail) over switches, there's no way to move the train except by switching back over to the diesel.
[[ Diesel operation isn't (or at least wasn't) allowed in the tunnels, so they switched at C-H. ]]
Haha. I worked on the territory involved much of my career. The secret most folks don't know is that for years, the trains (pulled by the FL-9 "dual mode" diesels) ran into and out of GCT "on diesel", because the "electric" propulsion system didn't work. For a while, the Amtrak engines didn't even have third rail shoes.
Back in the early days of Metro-North, when the FL-9's were aging and they had no power with which to run the trains, MN leased some Conrail B23-7 freight diesels. These had no third-rail capabilities AT ALL. And they ran them into G.C.T. on passenger trains when they had to. The trains had to move, so they used what they had.
The "no diesels in the tunnel" was - and IS - wool pulled over the public's eye...
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wrote:

I stand corrected. I don't believe it was that way when I lived there. The change-over was at C-H, then. Thinking about it, we changed trains at C-H.

Are you saying that they don't use any electric trains from C-H, anymore?

I assumed that Amtrack tracks weren't electrified.

I stand corrected. Thank you.
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<stuff snipped>

Thanks for input, that's what I thought I read in the brief initial reports.
The more I played with train cars tonight the more I believe that pushing is probably going to turn out to be statistically higher in deaths per mile than pulling. Pushed cars tend to sway out in response to force from behind. Pulled cars have a much higher resistance to jack-knifing.
It's pretty remarkably easy to demonstrate with toy train cars. If the lead car of a pushed train derails, the cars behind will jack-knife. A heavy locomotive might easily dislodge an obstruction on the track like a car whereas an aluminum commuter train car acting as the lead might not.
Whatever the cause, it's going to be an interesting investigation. In this day and age of instant computerized control, excessive speed should be caught pretty early and possibly automatically. I remember that after years of driving little sports cars I switched to a minivan and realized, in white-knuckled, feeling the van lift up slightly panic, that I couldn't take curves at anywhere NEAR the speed that I used to in a little Honda. (-:
OTOH, my occasional race car driving wife says "if your rear wheels don't "drift" through a turn, you're not going fast enough." With all these automatic control and braking systems it's hard to believe, given the less-than-stellar record of at least a few train drivers, that some automatic system would NOT put on the brakes before entering a curve at a speed guaranteed to cause a derailment.
--
Bobby G.



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On Mon, 2 Dec 2013 22:49:34 -0500, "Robert Green"

Sure. You can't push with a rope. The only thing keeping the "rope" stiff are the rails/flanges.

Sounds like speed. 82MPH on that garbage infrastructure is *nuts*.

I think we can see what happens when train wheels "drift". There are no such systems on these trains. The equipment is *really* crude.
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On 12/3/13 1:45 PM, snipped-for-privacy@attt.bizz wrote:

Wrong.
The track on the MN Hudson line is built to high standards.
Examine closely pics of the wreck, and you'll see that the track the train jumped doesn't show much damage at all. Welded heavyweight rail and concrete ties.
NO train is going to attempt to negotiate a 30mph curve at 80+ and stay on the tracks.
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wrote:

When? It was barely usable 20 years ago. The trains would list >10 degrees on straights.

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On 12/2/2013 11:40 AM, snipped-for-privacy@attt.bizz wrote: ...

Although depending on grade and loading, they often add "helpers" in the middle and/or at the rear as well.
"Helper", UT is aptly named--it's the location the D&RGW stationed additional engines to add to trains climbing Soldier Summit heading to Salt Lake. It's in Carbon County NW of Price. The county name gives a real hint as to the loading of most of the trains heading out...
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On 12/2/13 12:40 PM, snipped-for-privacy@attt.bizz wrote:

No, that's not the case. You're thinking of electrically-powered multiple-unit cars.
The train involved had unpowered coaches with a locomotive on the rear end and a "cab control car" at the opposite end (which in this instance was the front of the train). The cab car has a throttle and brake setup and the control circuits are carried through the coaches in the middle and back to a jumper connection on the engine.
Back when I was running trains, I never liked the cab control setup, but that was just me. First, being an engineman, I wanted to BE "on the engine" to better know what it was doing (you don't get enough feedback on the other end when the engine is pushing). Secondly, the ride is just rougher in push mode. Easier to control how the train handles when the engine is pulling.
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<stuff snipped>

I used to run trains, too. Lionel. (-; Seriously, I am jealous. A real train driver. I spent many hours riding in the front cars of the NYC subway trains back when a 15 cent token allowed you to ride anywhere without restriction. That was as close as I got. I am sure that at least some other AHR'ers did it, too. It's a great experience. Not sure modern subway cars allow it. Haven't ridden the NYC subway since 1980.

Feedback is incredibly important. A bad cable connection can knock out important controls and indicators and as you say, you can't feel unusual vibrations and noises that could indicate engine trouble.

That makes senses because it's a lot harder to stay on center when pushing than when pulling. The cars being pushed tend to want to go right or left and I'll bet there's quite a difference in the contact patch of rail and wheel, at least force-wise.
Would they ever run a four car train with the engine between cars 2 and 3? That would make it a hybrid push/pull train and could improve the handling characteristics because fewer cars are being pushed.
With modern GPS units able to tell a driver when he's exceeding the speed limit, how hard can it be to go one step further and have the train automatically slow in the situation that the Hudson MTA train driver was in. This is very interesting stuff:
http://en.wikipedia.org/wiki/Positive_train_control
<<Starting in 1990 the National Transportation Safety Board (NTSB) counted PTC among its "Most Wanted List of Transportation Safety Improvements."[4][5] At the time, the vast majority of rail lines relied on the human crew for complying with all safety rules, and a significant fraction of accidents were attributable to human error.[citation needed] In September 2008, Congress considered a new rail safety law that sets a deadline of December 15, 2015, for implementation of positive train control (PTC) technology across most of the U.S. rail network. The bill, ushered through the legislative process by the Senate Commerce Committee and the House Transportation and Infrastructure Committee, was developed in response to the collision of a Metrolink passenger train and a Union Pacific freight train September 12, 2008, in California, which resulted in the deaths of 25 and injuries to more than 135 passengers.>>
--
Bobby G.



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Robert Green wrote:

HO trains don't like being pushed very well around curves. I think it will be blamed on the speed. Do they have CC TV from the front car to the locomotive in the rear or are they blindly pushing?
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Bill
In Hamptonburgh, NY
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<stuff snipped>

I've been playing around with 027 trains but the same thing is true of them. If they derail or hit an obstruction, the cars behind will accordian outwards, or worse, telescope into each other.

Operator error. Ask any commercial pilot how blame is apportioned, if only for legal reasons.

I believe they have a control cab upfront that is connected to the pushing engine. From what little reading I've done so far, the configurations are many. The key factor seems to be that turning a train around requires a lot of real estate or a special roundhouse and these push/pull and other configurations eliminate the need to reverse the train.
I wonder if they have footage of the train derailing? More and more CCTV camera are being installed everywhere - they had an amazing amount of meteor footage from Russia that came from parking lot cameras, dashcams and even cell phones. There was a fascinating TV show about how they collected all those videos and were able to determine the meteorite's trajectory. It showed that it came directly out of the solar glare and was invisible to the asteroid detection cameras/satelites now in use because they are "blinded" by the sun.
--
Bobby G.



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On Mon, 2 Dec 2013 10:16:44 -0500, "Robert Green"

It's a pretty safe bet that pulling a train is inherently better. I have no doubt it's more stable and because it's more stable, more fuel efficient.
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but the RR was doing everything it could to delay implementation...just like a good conservative business would
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On Mon, 02 Dec 2013 21:28:11 -0800, "Malcom \"Mal\" Reynolds"

That's your government at work, Malformed.
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wrote:

and your free market does it best krwless
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On Thu, 26 Dec 2013 20:28:58 -0800, "Malcom \"Mal\" Reynolds"

You bet your ass it does, when it's allowed to. You lefties know nothing about it, though.
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auto speed control and auto brakes need to be standard everywhere.
on trains and mass transit its just common sense. but its coming on cars too...
the GPS knows what rad your on and limits max speed for everyones safety.
this day is fast approaching
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As long as an 'emergency' override exists, might be acceptable. Of course the EO would cause a feedback to authorities so they can jump in, dispatch vehicles, and 'help'
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bob haller wrote:

A smart phone has more intelligence than the railroads. What the RR needs. Like street traffic cameras, there should be some way to signal the engineer of the current speed zone or lower speed zones or impediments ahead. If a train exceeds the current speed limit or before entering a lower speed zone, there should be a warning signal in the locomotive to slow down. There should be cameras and warning systems at RR crossings to alert the engineer if there is an impediment at the crossing. If warned, the engineer can prepare to stop way before reaching the crossing. A train can take up a mile or more to stop so the warning should be given at least a mile further than the crossing. Of course, the train has to be further away than a mile when warned or there might not be time to stop.
The RRS have always been slow to make repairs to their equipment. Look how long it takes them to make repairs to RR crossings, if at all. Another thing, replace all crossing gate lights with LEDs so less of the light bulbs die. It'll save the RR money and that should be an incentive.
The most times that I have used a railroad was when I lived in the Bronx back in the late 1940s, and that was the NYC Subway. The 3 times I rode in an outdoor railroad was when I rode from the Bronx to Bainbridge MD in July of 1955, Norfolk VA to Boston MA in 1956, and from southern France to southern Spain in the late 1950s. All were when I was in the Navy.
--
Bill
In Hamptonburgh, NY
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