# Over under....



## TheFishGuy (Feb 1, 2011)

Dumb question... How many feet of track would YOU suggest there be from when the track goes over one track then needs to go under another? 
I'm in the design stage of my layout and I think I've got a spot that's going to be cutting to close. My fear is that the grade will be too great...

Question 2: What do YOU suggest the clearance should be from top of rail to bottom of bridge or tunnel above it?

Thanks fellas.


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## Hagen (Jan 10, 2008)

the distance depends on clearance, clearance depends on your equipment/scale.


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## NTCGRR (Jan 2, 2008)

I have min 8" wide and 11" tall off rail because folks with 1:20 scale locos come and visit. Plus I run modern double stack cars. 10" would work. 
If you run short trains 3% grade could work.


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## Bunker (Feb 7, 2009)

I have seen some substantial grade changes on some rr's. For me the easiest way to calculate grade is 1" to 8' is ~ a 1% grade. Staying under a 3% grade for electric trains is what I was taught. For live steam, level is best. 

If you want 9" clearance at the crossover, 9" times 8' is 72 of track or a bit more than the circumference of a 20' diameter circle'.


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## Pete Thornton (Jan 2, 2008)

My fear is that the grade will be too great 
That's why they invented the Shay . . .


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## kormsen (Oct 27, 2009)

you will need at least 16 foot (if your locos are mountaingoats) 
or 26 foot for the 3% grade Marty suggests.


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## TheFishGuy (Feb 1, 2011)

Posted By Hagen on 04 Aug 2011 04:52 AM 
the distance depends on clearance, clearance depends on your equipment/scale.

OK, you got me on that one.... I have all 1/29th G scale... and I surely don't have 16' or 26' to make the grade to 10"...


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## TheFishGuy (Feb 1, 2011)

Here's a picture of what I'd like to try and do. There's plenty of time for correcting or suggestions. I probably won't get to this for a while, so untill then I'm doing plenty of planning and research. Here's a direct link to the pic( copy and paste into your web brouser to view): 

http://i47.photobucket.com/albums/f197/jstraz/Trains/Gscalelayout.jpg


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## Hagen (Jan 10, 2008)

Posted By TheFishGuy on 04 Aug 2011 03:03 PM 
OK, you got me on that one.... I have all 1/29th G scale... and I surely don't have 16' or 26' to make the grade to 10"... 



Then you may get away with less, as there is less clearance to worry about. Will you ever be getting any 1/20.3 equipment? will you have friends over that will want to run such equipment?
Will you be running double stacks? or just "normal" freight/passenger equipment?


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## rsmproductions (Jan 5, 2008)

I just did the grade on my new addition...I had 44' to get from ground zero to 13"...I figured approximately 2.7% grade. I basically raised the track 1/2' every 18"...it seems to work ok. 

If you don't have the room for a straight shot perhaps you could build a helix in order to get the train to the heigth you need... 

Richard


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## Hagen (Jan 10, 2008)

It sounds like you do not have the room for an over under at all.
How much space do you have?


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## Dan Pierce (Jan 2, 2008)

Or get a Cog engine and do a 15 per cent grade!!


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## TheFishGuy (Feb 1, 2011)

Posted By TheFishGuy on 04 Aug 2011 04:58 PM 
Here's a picture of what I'd like to try and do. There's plenty of time for correcting or suggestions. I probably won't get to this for a while, so untill then I'm doing plenty of planning and research. Here's a direct link to the pic( copy and paste into your web brouser to view): 

http://i47.photobucket.com/albums/f...layout.jpg 
1/2" every 18".... Sounds doable with a bit of design change.

I'm pretty confident no one will be coming over to run trains, and I'm also pretty confident I'll stick with 1/29. As for double stacks... Some day when I can afford it...


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## Phippsburg Eric (Jan 10, 2008)

give yourself as much track as you can and make the clearance as small as you can...Measure your tallest peice of equipment, give yourself some extra space and call it good. my covered bridges have 8-1/2" of clearance which is plenty even for those big Colorado Narrow gauge engines in 1:20 scale you should be OK in the 7-8" range. 

Try it, if it works you are in the money, if not just make a on grade crossing.


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## kormsen (Oct 27, 2009)

Posted By rsmproductions on 05 Aug 2011 01:38 AM
If you don't have the room for a straight shot perhaps you could build a helix in order to get the train to the heigth you need... 


i don't think that a helix helps (in largescale)
because on curves you can not have as much grade.
by trial and error i came to the opinion, that R1 curves produce so much drag by themselves, that the grade can not be more than half of that, what a straight could have.


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## Dwight Ennis (Jan 2, 2008)

Looking at your plan, I'd estimate somewhere around 36' of track between the crossover point on the top section. 8' diameter curves have a roughly 25' circumference, and you have 3/4 of a complete curve, so that's 18-3/4' in the curves. On the top half, add to that 5' on one straight, about 10' between the crossover and the beginning of the 1/2 curve on the lower horizontal section, and about 3' between the crossover and the beginning of the 1/4 curve on the vertical section. 18-3/4 + 5 + 10 + 3 = 36-3/4'. 

On the bottom half you again have 3/4 of a complete curve of 8' diameter, so again 18-3/4 feet. 3' of straight of the 13' to the right of the crossover, 5' - then 3' - then 2-1/2' of straights, and 1' of the vertical section between the crossover and the beginning of the S curve. If the S curve is also 8' diameter curves, and if the reverse is at 45 degrees, that's 1/8 of a complete curve each side for another 1/4 of a complete curve = another 6-1/4 feet. 18-3/4 + 3 + 5 + 3 + 2-1/2 + 1 + 6-1/4 = 40' on the bottom section. 

The shortest of these is 36-3/4' = 441" / 9" = 49" of track per 1" rise, or roughly 1" rise per 4' of track. That's roughly a 2% grade. Seems like it would work. However, you will need some kind of bridge support under the upper track at the crossing point and that will add another 1/2" minimum. Also add the thickness of the track itself, so you'll need 10" total clearance to get 9" clear for a train to pass under. That's still 44" of track per 1" rise - still just a little over a 2-1/4% grade. Even compensating for much of the grade being on curves, I still think most locos could haul a reasonable train for a small layout up such a grade. 

One tip though - put a straight section equal to the length of one car in the middle of the S curve. It will steepen the grade slightly by cutting out a small bit of length, but that's on the longer of the two sections anyway, and it will help reduce derailments and coupler misalignments substantially.


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## TheFishGuy (Feb 1, 2011)

Thank you for the tip. I apreciate it... Let's complicate it a little more.... If you open the link again I'll talk you through it... 









On the right side of the drawing where there's a 10' straight away on the red line and a 5' straight away on the green line I plan to connect both lines with two RH switches and two LH switches. 

Kind of like this: 

l l 
l\l 
l l 
l/l 
l l 
l l 
l l 

To explain it even furthur, the 4' straight away will go over the 13' straight away in the green line. 

BUT! The entire top left of the green line will go over the red line. Obviously I'll have plenty of line to "lower" the red line. 

I envision the 10' curve, half of the 10' straight away and half of the 11'8" straight away to be below grade. 
See any problem with this?
I will be shooting grades with my transit in order to install proper drainage. 
I like water features and plan to have an elaborate one wind through this layout. 
I have drawn this layout to scale on the free version of "Train Player 4" then copied it by laying a piece of paper over the monitor then scanning it... I'm a cheater, what can I say.  

We, my sons and I, love tunnels and bridges so we plan to have plenty on this layout. I'm a carpenter by trade so building the bridges should be fun. 
I'm also friends with a few welders who are psyched about building me a scale model of a train bridge much like this one: 

http://www.redgage.com/photos/goldenpig/back-road-train-bridge.html 

At any rate... thanks for the responses...


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## Hagen (Jan 10, 2008)

I just measured my steepest grade, and it's 3% On there even the Mikado may slip with some 14 cars (or five Beerladen gondolas). So that is the grade I need "sand" and weight to get up.


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## kormsen (Oct 27, 2009)

on my last layout i had a very steep grade. 

i "sanded" the track with very coarse sanding paper, moving it sideways. 
that gave me two extra wagons to hang behind the locos.


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## Hagen (Jan 10, 2008)

basicly... 1 percent incline is 1'/100' or 1"/100" or 1cm/1m and as I just found out I allready have a near 3% incline on my railway and I wouldn't recommend it for anything but heavy locos with light load.


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## chuck n (Jan 2, 2008)

One other way to get clearance at the cross over is to put a dip in the track going under. You could do that with a slight grade down and back up the other side. This will help you keep all of the grade off the over track.

This is done by the 1:1 guys, with half of the grade going up on one track and half going down on the other. With this it is possible to get the necessary clearance in half of the space. If you try this, you will have to have some good drainage at the low point.


Chuck


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## TheFishGuy (Feb 1, 2011)

Interesting Chuck n.... Thank you. 

As far as grade is concerned, you're looking at it the wrong way... 
I'll simplify it, 100% grade is a 45* angle. 
Grade is simply determined by the degree of the angle calibrated from level.  
For example, rising 1" in ten feet is roughly a .8333333333333333% grade. 
Use this formula: 1" / 120" x 100 = grade 
Therefore a 3% grade is 3.6" in 10 feet.  
So, if I need three time 3.6 (10.8) I need to do it in 30' 

Check this out... Most people have these levels: 
http://www.bikesatwork.com/hauling-cargo-by-bike/how-to-measure-grade.html 

Also, check this out: 
http://en.wikipedia.org/wiki/Grade_(slope) 

Have fun figuring your grades!


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## Dwight Ennis (Jan 2, 2008)

With this it is possible to get the necessary clearance in half of the space.Not true. The length of track needed to rise a given distance at a given grade remains the same regardless of whether one starts and ground level and rises the entire distance or starts at half the distance below ground level and rises to half the distance above ground level.


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## chuck n (Jan 2, 2008)

Dwight:

You save length of rise because one track only has to go up 4.5" while the other drops 4.5" giving you a clearance of 9". To atain a grade elevation of 9", with the lower track level, it would require twice the length of track that a 4.5" elevation gain would need. This should apply is the grade is the same in both instances.


Chuck


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## Polaris1 (Jan 22, 2010)

There are two items to consider here: 

If we talk 1 main line over & under, Dwight is correct. 

If we talk two different main lines over & under, Dwight may be wrong..??//


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## Dwight Ennis (Jan 2, 2008)

Chuck - a train starting from 4.5" below ground level still needs to rise 9" to reach 4.5" above ground level. The length of track needed to rise that 9" in total elevation is exactly the same for a given grade regardless of the elevation the train starts at so no track is saved at all. 

Example 1 - a train starts at ground level and needs to rise to 9" above ground level at a steady 2% grade. The total elevation gain needed is 9". It will need 9/0.02 = 450" or 37'-6" of track to do so. 

Example 2 - a train starts at 4.5" below ground level and needs to rise to 4.5" above ground level at a steady 2% grade. The total elevation gain needed is still 9". It will still need 9/0.02 = 450" or 37'-6" of track to do so. 

No difference. My participation in this discussion has only talked about the inner line crossing over itself. It's the shorter of the two loops and seemed the crux of the original question.


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## Hagen (Jan 10, 2008)

Dwight

If both tracks converge at a point (station or somesuch) and one track goes down from the station and the other goes up it will be possible for the elevated track to go over the other at half the distance from the station compared to a situation where one track remains level.
Where both tracks change "height" you will reach 20cm clearance after only 10m while if on remains level you will need 20m to get a 20cm clearance (at 1% grade) or 12" after 60" instead of 120"


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## Ironton (Jan 2, 2008)

Dwight 

Save your breath. I tried to make your point the last time this this topic came up and they would not listen. 

Somehow the idea that only half of the track is above grade means you only need half the distance is what they see. The half that is below grade does not seem to register with them (or they think 1/2 plus 1/2 equals 1/2, sounds like some of my ex students).


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## chuck n (Jan 2, 2008)

Guys:

You still need the entire distance. Only in this case it is accomplished in two shorter segments rather than one long one. If space is a problem, this approach might help. It will in fact be a little longer in total because you will need an extra piece on level track for the base of the dip to ease the transition from the decline to the incline.


Chuck 


PS I never said that you will get by with half of the track. Only that the space required would be shorter on each segment.


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## Dwight Ennis (Jan 2, 2008)

The original question...Dumb question... *How many feet of track* would YOU suggest there be from when the track goes over one track then needs to go under another? 
(bolding mine)
This is the question I have endeavored to address. In looking at the track plan, the obvious limitation to my mind was the shorter loop - the green loop - crossing over itself. Within that context, the "feet of track" (original phrasing) required to gain a 9" separation at the crossing point will remain constant for a given grade regardless of starting elevation. Within that context, and since the "feet of track" required remains the same, and as the track plan also remains the same, the phrase "saving space" is, to my mind, meaningless.

The crossing of the green line over the red line is a place where placing the red line in a cut below ground level has merit, bit the "space" needed to achieve sufficient clearance will also remain the same since the "feet of track" required to achieve this clearance for a given grade again remains the same.

So maybe were debating semantics here, but within the limitations imposed by both the track plan as shown, and the original question about "feet of track", I can envision no "space savings." The space is already imposed by the track plan.


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## Hagen (Jan 10, 2008)

Posted By Ironton on 09 Aug 2011 06:11 AM 
Dwight 

Save your breath. I tried to make your point the last time this this topic came up and they would not listen. 

Somehow the idea that only half of the track is above grade means you only need half the distance is what they see. The half that is below grade does not seem to register with them (or they think 1/2 plus 1/2 equals 1/2, sounds like some of my ex students). 
1/2 plus 1/2 equals one full length, so you can squeeze one full length into (about) half the "space". Seems logical to me. Then I am not a maths teacher

But, it may require changes to the trackplan


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## TheFishGuy (Feb 1, 2011)

Woa! For some reson I wasn't notified of responses... I'm going to bring some track in from the barn today and test some things out in the livingroom... Mom aught to be so excited... LOL


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