# track length per height?



## zorba (Aug 6, 2012)

i could never get my head around slope grades etc.

all i need to know is how much track in length do you need to get to a height required to allow for a tunnel in H0 scale?

basically ive got 2 loops, i want the outer loop to elevate, and when it reaches the right height the "mountain" will then extend out over the inner loop putting it in a tunnel. 

(and mind you this is all in my head at the moment.)


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## NIMT (Jan 6, 2011)

Another *chart* for proper clearance's


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## tjcruiser (Jan 10, 2010)

Just adding to Sean's info, above ...

In model RR, a 2% grade is common ... about 48" of horizontal "run" for every 1" of vertical rise.

That said, model RR real estate is a precious commodity, and people often don't have that much runway. 3% could be a choice to consider, and for strong engines and/or short loads (few cars in tow), 4% would be pretty aggressive.

TJ


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## manchesterjim (Dec 30, 2011)

tjcruiser said:


> Just adding to Sean's info, above ...
> 
> In model RR, a 2% grade is common ... about 48" of horizontal "run" for every 1" of vertical rise.
> 
> ...


I haven't done anything yet with elevations (but I'm building that into the new generation), however I think that a good 3% grade and running a consist of 2 locos or more would be a pretty realistic thing to see! 

For the one I'm building.....I have double mains. On one end of the run, there will be an option to take the longer, elevated route. If I don't think a particular consist will handle it, I can chose the "low road"! 

Jim


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## zorba (Aug 6, 2012)

i think the engine i have (one of them) is pretty strong, and im not going to be pulling 10 - 15 cars like some of the vids ive seen here, maybe 5 - 7 at most. so i would say 3 - 3.5% should be ok?

even at 4% you need 2.25m of track to get to clearance height and another 2.25 track to get down. thats 4.5m of track total just for that part. 

hrm. i need to get the plan book off my old man and start working it as the book has the plan he wants to copy directly but i want to modify it to have an elevation and tunnel as described above.


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## tkruger (Jan 18, 2009)

Consider this to avoid an error that I did. The figures in that chart are for straight runs. If there are curves you will need a longer run to reach the height. Going around a curve reduces the tractive effort of your locomotive. This is because one of the wheels must slip due to the lack of a differential. This decreases the number of wheels actually pulling on the locomotive. 

I found this out the hard way by cork-screwing up a hill on my lay out with a 3.5% grade. Only my larges engines could pull the large trains on the mountain run. Since that discovery a bypass was added.


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## zorba (Aug 6, 2012)

i was thinking of halving the distance required byt having one track go up and the other go down.

will require some effort tho.


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## cv_acr (Oct 28, 2011)

As easier way to figure grade than using a chart or table is to use the simple formula for the slope of a line.

It's simply:

slope = rise / run

Multiply by 100 to make it a percentage.

If you know the grade (slope) and height (rise) required, just reverse the calculation to solve for distance (run).* Basic high school math from this point forward.

*(Caveat: you'll probably end up wanting to add a little bit to the distance to allow for the transition from grade to flat. If it's too abrupt, bad things like pilots bottoming out at the bottom of the grade or couplers separating at the top of the grade can occur. )


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## Carl (Feb 19, 2012)

As indicated up, the best advice one can offer is to use a 2% slope. It seems that when one goes beyond 2%, all kinds of funny things happen, some or total loss of traction, especially has the number of cars being pulled is increased.


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