Heighth and weight of rails

[tstage]

Hi Everyone!

(I already posed this question over on the Prototype forum. I got a couple of responses in the last day or so, so I thought I'd post it here, as well, for some additional input.)

Is it fairly prototypical to always have a mainline higher than the siding? On one particular stretch of highway close to home, their are 2 main line tracks and one siding that run parallel with the road. The siding is in front and is noticably a foot or so lower than the other two tracks. Would that also be true as the mainline travels through a yard.

The reason for asking. I was at a train show a couple of weekends ago and was looking at a module layout that one of the local clubs had set up. As I was looking at the yard area, I noticed that the yard itself was graded lower than the main running through it, and that the turnout and subsequent track leading into the yard area was graded down into the yard. Would this be normal and prototypical in a real yard situation. If so, why?

Also, why is it common practice to run lighter weight (90-lb.) rail in yards, sidings, and branchline than on the main. It seems to me that you would want a heavier weight (e.g. 132-lb.) rail in the yard to handle the static weight of all the cars and locomotives. (Key phrase: "Seems to me...")

Anyhow, sorry for showing my ignorance here but I had to ask. Thanks for your responses. [:)]

Tom

[Anonymous]

Putting sidings lower than the main means that runaway cars cannot climb onto the main line and cause "problems".

I would think (key phrase... [;)]) that the heavier weight rail on the mains is there to take the pounding of cars moving at high speed. Much more twisting/pounding/stress than slow movements of cuts of cars in a yard.

Andrew

[selector]

QUOTE: Originally posted by masonjar

Putting sidings lower than the main means that runaway cars cannot climb onto the main line and cause "problems".

I would think (key phrase... [;)]) that the heavier weight rail on the mains is there to take the pounding of cars moving at high speed. Much more twisting/pounding/stress than slow movements of cuts of cars in a yard.

Andrew

Yup, the grade down to the siding or yard tracks means a runaway car won't stop on a switch and foul the main. It would have to be running really hard, and that is unlikely, to make it up to the frog and beyond.

Heavy trains passing over a given point cause the rails to squirm and depress and rise, placing a great strain on the rails and their fastening and anchoring system. The heavier rail, ballast, and ties kept it all manageable.

[Anonymous]

To Selector's point: I always found it disconcerting when I lived in NY to watch a Long Island Railroad train pass me in a station and observe just how much the rails rose, sank and shimmied around as it went over - and those aren't especially heavy trains (though they typicall ran 50-60mph on the line I used)

[selector]

K, have you ever closely observed the stanchions supporting modern roller coaster tracks as the train passes by? Now THAT'S scary!!

[Anonymous]

All the flexing and movement (to a certain point... [;)]) is required. It is part of the design of the rials (or whatever) in order to handle the loading imposed upon it. Can you imagine how strong tracks/frames/airplane wings would have to be not to move at all...?!?!

If you ever see a plane wing that won't flex - get off the plane! It's likely to snap off during the flight!

Andrew

[BR60103]

Sidings aren't always lower. Because of the land shape, I know a number that rise away from the main tracks to a warehouse. These usually run off a separate track (not the main line) and always have a derail uphill from the switch.
There's also a local spot where the side track is less graded than the main line and goes up and down compared to the main.

[cwclark]

QUOTE: Originally posted by BR60103

Sidings aren't always lower. Because of the land shape, I know a number that rise away from the main tracks to a warehouse. These usually run off a separate track (not the main line) and always have a derail uphill from the switch.
There's also a local spot where the side track is less graded than the main line and goes up and down compared to the main.

I have to agree with this statement...I would think the type and height of the tracks that are in the yard are dictated by the ground given and preparation of the ground to build them on..i've seen tracks higher and lower than mains and the yard I go by on my way home everyday has perfectly level tracks..all the mains and the sidings in the yard are all the same size track and rail height....it probably depends on the builder and the specs given to him and by the budget alloted to the builder to put them in..chuck