OT: Push v. pull commuter trains

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'

Reply to
RobertMacy
Loading thread data ...

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.

Reply to
willshak

Right. But isn't it still all electric below C-H?

But running on the traction motors below C-H. Diesel operation isn't (or at least wasn't) allowed in the tunnels, so they switched at C-H.

Reply to
krw

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.

Reply to
krw

That's your government at work, Malformed.

Reply to
krw

In the medical field, there are two types of research. The controlled experiment and the epidemiological study. Despite lack of controls or rigorous design, epidemiological studies nevertheless reveal important information that is usually not exposed in smaller, "controlled" experiments.

Thalidomide passed numerous controlled experiments worldwide but it wasn't until the drug was widely used that epidemiological studies revealed that taking a certain amount of the drug during a very small window of a woman's pregnancy caused serious flipper-limb birth defects. Oraflex, Phen-fen and numerous other drugs that passed controlled, small-scale experiments were revealed to be dangerous only after 1,000's of people had taken them.

The NFL insisted for a long time that football players weren't suffering from CTE. The tobacco industry concealed the lethality of smoking for far longer. It wasn't until epidemiological analysis that those concealments were revealed. I think it's safe to say that railroads, struggling as they are, have a financial incentive NOT to have to build mechanisms to reverse trains so that the locomotive always leads - the way railroads have been run since their inception. They have a strong financial incentive to dispute that push trains are any more dangerous than pulled ones.

Now that we have remote cabs and CCTV cameras it's possible to run trains "backwards" but as John Albert, apparently a train drive himself, pointed out earlier, running a train from a control cab is NOT the same as running it from a lead locomotive. Important sensory information is not relayed through the cable links. More importantly, cable links introduce another serious level of potential failure.

While I agree that it's going to be very hard to winnow out all the variables (and it's a reason they crash actual test planes to determine how things like "safe" fuel will react in an actual crash), analysis of the thousands of derailments that have occurred in the last decade could reveal trends relating to push or pulled trains. I'll keep nosing around because I'd like to find some actual studies done by the NTSB or others that are dispositive. An NTSB official saying he doesn't think there's any difference doesn't cut it for me. Government officials say a lot of things that aren't backed by reality. (-: Obamacare's website officials as a case in point.

As are many derailments. A figure I came across this morning implied that at least 40% of all derailments in the US are from operator error. The driver of the train in question has said he "zoned out" just before the crash. One thing that's been revealed is how hard the train industry has been fighting the adoption of PTC (positive train control) that's meant to automatically slow the train if potential derailment conditions are detected.

source:

formatting link

Sadly, many railroads are still lobbying for PTC exemptions as far out as

2018.

night it was purely momentum from the velocity and would have been about

I agree that's likely but there's still the issue of cars following a massive locomotive in a string and that massive locomotive plowing through a string of cars ahead of it. I disagree that a locomotive pulling cars off the track in a derailment would evidence the same scatter of rail cars that a locomotive plowing through the cars ahead of it would.

Find a toy train set, like I did and you'll immediately see the difference. The mass of a locomotive behind a string of cars that have derailed tends to force the cars ahead to pivot at the couplings and accordion outwards. When lighter cars follow a much heavier derailed locomotive they tend to stay in much more of string like pearls, at least from the aerial photographs (search Google, there are hundreds of photos)

I'll readily admit that the photos are not proof of anything without a lot of detailed research about the nature of the underlying crash and the configuration of the train involved. They do make for interesting viewing, though.

This article:

formatting link

I am with Bill H. on this. It seems obvious to me that a big locomotive in front *can't* plow through cars ahead the way a pusher locomotive can and a front engine provides a lot of mass to absorb any impact with something blocking the tracks. A good parallel might be the examination of driver fatalities in rear v. front engine cars.

I don't agree with that statement - at least in general. While this crash may have happened the way it did no matter what, the more I read the more I come across people who believe that push trains are inherently more likely to suffer more damage. That makes sense because of the heavier locomotive having to dissipate its momentum through the leading train cars in a crash.

As for the motivation to do further research, the number of deaths and injuries leads me to believe that plaintiff lawyers are already engaging experts who are going to model the push v. pull issue if only to try to paint the procedure as inherently dangerous. Lawyers were the ones that eventually revealed the lies of Big Tobacco and the NFL. If there's an inherent problem in pushed trains, I'm betting attorneys and expert witnesses are already working to prove it.

In could easily turn out that this particular crash may serve to focus attention on whether trailing locomotives are more likely to cause greater damage in a derailment, no matter what the cause. One could even speculate that with a insanely high rate of speed as the Hudson train is alleged to have traveled that the momentum of the locomotive becomes a very decisive factor in the amount of damage caused to the cars ahead of it. In a pull train that momentum is likely to be absorbed by the engine plowing up the ground, not the cars ahead of it.

In any event, it's likely to be a very interesting investigation. Both the NTSB and the police are involved since this could end up being manslaughter or more if the train driver was impaired by drugs or was chatting on his cellphone (train drivers are allowed to carry, but not use them). I think one decisive element of the investigation will be precisely how those four passengers died. Were they in the car directly ahead of the locomotive? Same will hold true for where the most injuries occurred.

Reply to
Robert Green

On 12/3/2013 2:27 PM, Robert Green wrote: ...

W/ the resulting problem that "correlation does not imply causation".

The difference there is the is generally far more massive datasets available than I think you'll find that the number of derailments that have any conceivable bearing or resemblance to this have even occurred. You've got to have at least a modicum of similarity of events to have any chance at all and I'd be surprised if there were even 10 in the last

50 yrs of this type to compare to.

...

...

I don't need to; I've had toy trains (as well as 5+ yrs engineering school in physics-related fields of study plus 2+ in an actual physics department doing a MS). I kinda' understand applied forces and restraints... :)

_BUT_, if you'll look again at the aerials of the disposition of these cars, they're basically parallel to the tracks and rolled, very evident of the momentum of their velocity and much like an auto rolls. They're not particularly stacked up as tho the power unit ran thru them.

I've not looked for it again; but that surely is the appearance it gave me on the footage shown last night.

Reply to
dpb

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...

Reply to
John Albert

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.
Reply to
John Albert

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.

Reply to
krw

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

Reply to
krw

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:

formatting link

Reply to
Robert Green

That's always an issue but with 1,000s of derailment reports to analyze I believe that certain trends would reveal themselves from a thorough data analysis. Remember, I started this thread just to see if there's any data out there that would indicate pushed trains are less safe than pulled ones. (Actually, I really wanted to know if there's anything a passenger can do to help protect themselves from injury in a derailment. I suspect there's not much.)

When I did PC support at one of DC's big law firms we would start such an analysis by reviewing 100 or so typical reports, looking for potential categories to "code." In this case, we would select things like "push or pulled", number of injuries, number of fatalities, train speed, train length, NTSB determination of cause/fault, type of injuries sustained, types of equipment involved in crash, etc. Then we would hire paralegals to review each crash report and extract the data we were interested in into the fixed categories in a database record. I think you would be surprised how quickly certain trends reveal themselves through this kind of analysis. NDA's restrain me from discussing details, but they involve cases I am sure you've heard of. (-"

I think it's important to note that I'm not trying to use the Hudson derailment as proof of anything. It's probably not going to shed very much light on the push/pull issue since it's so clearly a speed-related one. But I would assume that by reviewing (and attempting to normalize and cross-level) the thousands of derailment reports out there that eventually any data that showed whether pushing is associated with higher injury/death/destruction levels would be revealed.

I don't think that really matters much in this sort of wide-ranging analysis. It would be difficult to come up with an absolute number, I agree, but if there's a correlation between pushed train derailments having greater injury, death or damage levels than pulled ones, this sort of ranked analysis will show it.

If 70% of pushed train derailments involve fatalities compared to say, 40% of pulled trains (hypothetically speaking), even without a "modicum of similarity" between various derailments you still have valid numbers that indicate that overall, pushed trains involve greater fatalities. I'm aware, BTW, that other factors have to be considered as well, but I still think that if you examine enough accidents, common threads will appear.

I would go further and say that accidents like the recent Hudson one might have to be excluded from the datasets because an 82 mile an hour run at a 30 mile an hour curve is going to spill the cars over a wide area no matter what the configuration of the train.

My guess is that fatalities in pushed train accidents are likely to occur when the lead car derails after striking an object or encountering "bad track." In those cases, the cars would not spill over wildly but would very likely telescope with the rear-mounted engine tending to plow into and collapse the leading cars.

OK - sorry, didn't mean to impugn your integrity or background. It's just that having spent some time pushing and pulling toy trains it seems pretty obvious that pushing has some issues (the tendency of pushed cars to swing out to the sides and pivot in a derailment). Ever since the NY Times did a huge series of article about how poorly grade crossings in the US are maintained I've wondered about how much we really know about things like train safety.

formatting link

It claimed that out of 3,000 crossing accidents in that year only 4 were investigated by the feds. The article discusses evidence tampering, black box malfunctions, maintenance, slow orders, etc. It's really an eye-opener and makes me wonder whether anyone's really looked into the push/pull incident at any depth.

Which is why this crash is probably not going to help answer the question of whether pushed trains are involved in more fatal accidents than pulled ones. But I am reasonably sure that data analysis *will* reveal cases where the engine of a pushed train did some serious damage to the leading cars, especially in accidents not involving high speed entries into low speed curves. It's just the plain ol' physics of momentum.

Don't disagree, but it's just one data point among thousands of derailments and one, that as you say, isn't particularly useful in answering the statistical question: are pushed train derailments more serious than pulled ones?

One of the subjects quoted in an article (a professor and ex-NTSB'er, IIRC) said there was no real difference. A good starting point would be for me to contact him and ask him what he based that conclusion on. Was it a detailed analysis of derailment data? Or just a hunch? (-:

Reply to
Robert Green

To REALLY show that pushed are not as safe as pulled, your historical data would also need to include some basis, like number of trains pulled and number of trains pushed, or per mile or something. Don't think you can get that data with any certainty. But, logic would say that pushed does not happen often, as in only used for conveniennce, short runs, takes too long to switch. Should be able to get the numbers of accidents with pushed versus pulled trains. From the concept that pushed is not used very often and the incidences of accidents involving a pushed train would seem to make your point.

Do you have that info?

How to protect yourself? Where to ride? Do seat belts help in a train crash?

It always amazed me that passenger cars were legislated to have seat belts, but those large, yellow school buses were exempted.

Reply to
RobertMacy

That's a good point. Push/pull seems to be largely confined to short haul, point-to-point commuter runs - couldn't give you a hard and fast figure even though I have been looking. Freight trains end up in huge freight yards with roundhouses, switching engines, etc. so it's much easier to "string together" the traditional locomotive followed by freight cars. The commuter run like my wife rides simply travels the same tracks every day, going usually from a rural to a metropolitan area where the push/pull configuration is very convenient.

In reading more about why PTC (Positive Train Control) hasn't thoroughly penetrated the industry, it turns out to be all about the dollars. I have come to believe that even if pushed trains were shown to be twice as dangerous as pulled ones, things wouldn't change because it would take so much money to build ways to turn such trains around.

I don't know where a magic transition point would be - 4X or 8X as dangerous or more - but it's already clear from the responses to Federally mandated railroad safety upgrades that the money to change things just isn't there. Many commuter trains are under constant threat of shutting down because ridership levels are too low. Add millions in PTC upgrade costs and they'll just close up shop.

I wish I did. Again, all I am really trying to figure out is if there's anything that a passenger like my wife can do to increase her chances of survival in an accident. A while back when our mutual friend at the NTSB was still alive, we had much the same discussion about air travel. It turned out that could knowing the maintenance history of the plane could save your life. There's actually pretty good information that shows that planes that have been returned to service after a serious accident (tail-dragging, running off the runaway or some sort of collision) have a much greater statistically significant chance of being involved in a fatal crash.

Remember the plane that flew into Mt. Fuji?

formatting link

And that was one of just many cases where an investigation showed that faulty maintenance procedures from a previous incident contributed to a fatal crash. I wish I could remember the others, but there were at least 5 significant fatal crashes (including one where an engine had fallen off because it had been removed for maintenance and re-mounted on the wing pylon insecurely - I think that was a fairly recent crash in NYC that was first thought to be a terrorist attack). The problem is that unlike CarFax, there's no JetFax that can tell you the plane that you are about to board has been maintained by morons.

Good questions. I wish I had the answers. There's small comfort in the fact that fatal crashes and derailments have very seriously tapered off with the new train control technologies. As more older cars and locomotives are retired, newer, safer ones are coming on line already equipped to interact smoothly with all the newer safety equipment. Ironically, but not unexpected, the safety numbers have sagged recently because the economic collapse of 2008 has hurt investment in infrastructure across the board. Even so, things are dramatically better than they were 25 years ago, primarily due to technological improvements.

Funny you should say that. One of the very first articles I wrote as a cub reported basically asked that question "Why no seat belts on schoolbuses?" The answer was about what you would expect: "Too expensive" based on analysis of school bus accidents that showed very few fatalities related to lack of seat belts and very little to be gained in the face of spending the billions it would take to put seat belts in all school busses.

I would have thought that school buses were an excellent place to get kids in the habit of wearing safety belts. Although my article was published over thirty years ago, not much has changed. Most school bus accidents are at slow speeds and involve vehicles that are much smaller so mass-wise, the smaller vehicle usually take much more of the "hurt."

I've had my wife take notice of the type of equipment she rides on and the age of the cars. In reading about PTC, it seems that manufacturers are embedding automatic train control systems in the newer vehicles. The cost of retrofit is prohibitive but the cost of making sure newer equipment is capable of automatic control is not. So, eventually trains like the Hudson MTA train will have GPS units like those for cars that "know" the layout of the train's travel path and can automatically reduce speed when approaching a 30 mph curve at 80+.

Reply to
Robert Green

From my fooling around with my neighbor's toy trains I've discovered that not only does pushing tend to want to make the cars being pushed veer off to the sides, there's also a tendency to try to lift the pushed car up. I suppose that's to be expected given the force being applied and the ways that force can be transmitted. I also suspect that pushing transfers a lot of force to the area of wheel/track contact and that any defect in the rails could cause that forward force to become a derailment. The physics of a pulled train's "contact patch" of wheel to rail has to be a lot different and I would think much more forgiving of a rail defect.

Tell me about it. Just this morning I went to push the bed back into position after changing the sheets and it veered off to the side. (-: That's somewhat of a function of the swivel casters having to reverse direction when going from pulled to pushed, but it still surprised me that I didn't think of that obvious example until I was actually pushing the bed.

The more I investigate, the more I think pushed trains are more problematic than pulled ones for the reasons that you and others have noted. But scientifically proving that contention isn't going to be easy. My interest in all this is limited to trying to come up with some survival advice for my wife and from what I can tell, praying is about as likely as anything else to work. I am trying to convince her to retire soon, so maybe saying "there's nothing you can do to protect yourself" will help "push" her in that direction. (Couldn't resist!)

From my years riding the Metroliner one thing I can note with assurance - there's an endless supply of idiots that think it's funny to leave huge pipes, sofas, trashcans and anything else that can be brought there onto the train tracks. Worse, yet, is that these idiots seem to know that a collision with debris is more likely if they place the stuff on the tracks just around a curve.

In addition there are the suicidal idiots who kill themselves by train without a thought to the poor engineer who's got to live with that image for the rest of his life. Note to suicidal people: Jump off a bridge, OD on Tylenol or buy a .45 pistol to eat and leave the poor engineers out of your depression.

Reply to
Robert Green

hear, hear.

but...suicides try to leave their corpse for those they wish to punish to find.

Reply to
RobertMacy

and your free market does it best krwless

Reply to
Malcom "Mal" Reynolds

You bet your ass it does, when it's allowed to. You lefties know nothing about it, though.

Reply to
krw

HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.