Coriolis effect . .why some N-S trains run backwards?

I think you have already answered your own question - your professor was full of (iron) horse-feathers!

Tracks wear on the outside of the turn, no matter which way the train is running! On straight stretches the flanges bounce around hunting for the rails, to put it simplistically.

WHAT?!?!?!  I'll give Sheldon (Big Bang Theory) a call.  I'm sure he'll have the answer.

 

Rick

That is a bit too "simplistically" put. In reality, real railroad wheels have very little flange contact, except on very curvy lines. Wheels have a 1 in 20 taper, while rails are "canted inward" at the same taper ratio, which keeps the wheels "centered" and reduces flange contact and resulting flange wear.

Metra probably has an operational reason for running the push-pulls the directin they do.   And it probably has something to with the maintenance facility.

 

As for turning, it is true, they don't seem to have one in chicago downtown, but then they don't need one.   Push pull works fine.

 

In Michigan, Amtrak runs push pull or used from Pontiac near detroit to Chicago.   

On the CN Line from Antioch through Lake Villa, Il., going to Chicago. It is pushing south and pulling north. Every day. All day.  It seems like it works pretty well.  Interesting from Hotwater.  I would think eliminating as much flange contact as possible with the rail is most desirable, keeping the drag from that contact to a minimum.

The only negative that I have heard discussed about push-pull is that the engineer is much more vulnerable in an accident in the push mode.  It is probably less expensive for the RR to not have to turn trains or engines, but at the expense of the engineer's safety.

 

Art

I think folks are agreeing that in the real world this isn't really considered to be an issue.  

 

For the theoretical side, I could probably look this up elsewhere, and not look so dumb, but how are the motors mounted in the locomotives?  I would assume in the trucks, but is rotation parallel to the wheels or are the motors perpendicular and geared 90 degrees?  Or are we talking about only the forces of the diesel engine?  

But dont you wind up with uneven wear on the outside rail of a curve due to the outside wheel needing spin faster than the inside wheel?

As large as trains are to us humans, I don't think the Coriolis effect would be a significant force on rail wear - push-pull is just an efficient way of moving trains, whether through a lokey at each end, or control cab and a single lokey. 

 

Matt, 

i think the speed of the outside wheel is the same as the inside, provided the axle is locked to the wheels. It would still seem to produce the said wear as the surface feet per minute speed would increase still causing a spinning condition. On faster curves the outside rail is elevated to off set this as well as accommodate faster speeds. 

Mark

Actually, not a silly question. For a bag to be capable of holding 1000 pounds of iron, it would have to be much stronger (thicker, heavier material, whatever) than a bag holding 1000 pounds of feathers. Therefore the answer is probably unknown.

 

Rather than ask this of Sheldon, I suspect it would be better to ask Penny after a couple of glasses of wine. The answer would likely be consistent with the importance of the question.

 

Gerry

Curves on train tracks are there for one reason only, to keep trains from running off the edge of the earth! (same as a layout, without curves, were would our trains end up?). There, I said it.

Metra, and all commuter agencies that use diesel powered locomotion, all run trains "backwards" to help keep diesel fumes out of the city terminals.

 

It also saves the costs involved of turning locomotives or entire trains.  Plus, if a replacement locomotive is needed, it's already facing the correct direction.

 

BTW, the push-pull concept was initiated in the U.S. by the C&NW in 1959.

 

Rusty

I thought the reason why passenger trains were backed into a station was from back during steam operations didn't want the smoke in the station. Same should apply to diesel.

 

Also if you had to turn the train, it would take another, wait, 15 minutes? When I took the Amtrak from Champaign to Chicago, they had to turn it before entering the station.

 

Could you imagine the switch nightmare trying to have the ability to turn every line into station?

 

(Chicago has three commuter rail road stations, Ogilvy==trains from the north, Union==trains from the south, and whatever the IC is called now down near the lake shore).

 

Watch out, there is a bunch of BS associated with that Coriolis affect, to the point I would have to research to found out the truth. Same applies to the gyroscopic effect of a bicycle wheel, that is BS too, it the front rake or camber or whatever its called that helps keep a bicycle up. My younger brother did something with a prof at U of I where he put an opposing bicycle wheel above both regular wheels, and one could still easily ride it, but would of course get laughed at doing so.

 

Watch out, there is a bunch of BS associated with that Coriolis affect

Mike 

 

the Coriolis effect is used extensively in weather predictions so the effect may be small as to locomotives but not so as to atmospheric physics. Einstein was no slouch either. 

Just to set the record straight, there is a way to turn engines/trains at Chicago Union Station by way of a wye where the station tracks meet the BNSF line about two miles south of the station.  That's been there a long time as I can remember PRR trains being turned there.

 

Chuck

Once again, I was not absolutely clear.

 

Yes, there is a wye at Union station, or at least in the 1980's and I believe I saw it in Google maps about 3 years ago, it is how the Amtrak got into Union station.

 

I also thought the Illinois Central ran their commuter trains backwards in steam days, that's why the light way up on the tender of whatever engine that is at the Illinois Railway Museum, maybe #110??? 3709

The likes of #201 may have run backwards, but they would've always at the head of the train.  I can't imagine running commuter trains backwards with just a "tail hose man,"  particularly in the dead of winter on an open platform coach.

 

 

Rusty

Theres some interesting information!

 

I've never given much thought to the taper on train wheels, and would NEVER have guessed it keeps them centered on the rails to minimize flange contact.

 

Thankyou Hot Water.

My....goodness.

=======

Much if this thread does remind me of something that I learned from a comic book in the 50's. I forget whether it was Donald or Daffy Duck (seems like Donald, but this sounds more like Warner Bros.), but one of them was lost in the woods and suddenly remembered that:

 

"moss always grows on the wrong side of the tree".

 

He then realized that he knew which way to go. 

 

Words to live by.

 

My.... goodness is right.

 

This reminds me of the hotly contested and well reasoned scientific debate about the flight characteristics and migratory habits of the European Swallow versus the African Swallow.

 

Your professor.....he's on the tractor.....again!  

 

 

Hey, PhD....Piled Higher, Deeper...very apt.

 

Of course what's needed is a piece of Federal or State legislation to control the hemispherical Coriolis Effect lest it exacerbate the climate changes Federal or State legislation is already designed to control.

 

OTOH, it'll be here soon enough.

 

 

 

 

I believe they do not so much fly, as plummet........probably the Coriolis effect of the coconuts said bird is forced to carry................

Back to the terminals. Chicago has terminals, not stations. The difference is that a terminal is end of track. Yes, runaround tracks and others exist, but commuter service is very different.  The engineer in a push-pull train is sitting at the end thats going forward. He's at the top of the end car as its entering the terminal. He has a clear view of the track ahead.

 The real reason that they dont turn the train or engine, is that its expensive to do so. The second reason is there is no need because the train cars are designed to run backwards. Originally, steam equipment was turned around or disconnected, and the coaches pushed into the terminal, to avoid the smoke, and the hazards of walking past the live steam to get to the building.

 

As far as the Coriollis effect, just because he's a professor, doesnt mean he knows what he's talking about.  I have run some real word experiments on this. Quite interesting results.

The coriolus effect  causes storms to spin clockwise in the northern hemisphere effects ocean currents, rocket trajectory and the spin of toilets but the effect on trains would not be significant.
If you were to aim a rocket south from NY straight toward Miami it would land to the right or west due to the difference in radial velocity between NY and Miami. works in reverse too. Except the rocket would land to the right or east of NY.