# Grading and Bridges



## monsterram1500 (Oct 13, 2015)

I need help figuring out the incline grading i need to reach the level of a bridge. On one of my kits it says it 26"long and 11 1/2" high. Scale 188'x82'. I have searched high and low to try to understand this, but I have turned up nothing that would answer my question. I attached 2 pics of the bridges I want to use. The second one doesn't have any kind of height. only length and width.


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## Lehigh74 (Sep 25, 2015)

The grade required depends on the length and height. A 2% grade would rise 1 foot in 50 feet. I don't see the pictures.


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## Lemonhawk (Sep 24, 2013)

HO scale 188 x 12 inches in a foot / 87 (the HO scale) and you get 25.931 inches - is that what your after? Conversely if you have the scaled inches for example the width of 11.5 inches then x 87 gives you 1000.5 inches / 12 inches per foot you get 83.375 feet in the real world.


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## monsterram1500 (Oct 13, 2015)

here are the pics


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## cole226 (Feb 8, 2013)

in your situation i don't think you want your track to go up to the bridge, you want your valley to drop away from your roadbed and bridge.


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## flyboy2610 (Jan 20, 2010)

That would be my suggestion as well.
There was a movie called "Don't Raise the Bridge, Lower the River". It had Jerry Lewis, and Patricia Routledge, who is best known as Hyacinth Bucket in the British comedy "Keeping up Appearances".
Anyway, the movie title is good advice for HO layouts.


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## Lehigh74 (Sep 25, 2015)

I agree with cole and flyboy. You would need a very large layout if you wanted to set either bridge on top of your platform and have a reasonable grade that would raise the track level to the bridge. Much better to make a valley equal in depth to the height of the bridge. One alternative is to make the valley depth a portion of the bridge height and have a second track level with a shorter grade to reach the bridge. Another option is to have an upper level independent of the first (no grade between track levels).

Here is an example of a valley with depth equal to the bridge height and another with the valley about 2/3 of the bridge height. 

By the way, those look like some nice kits.


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## monsterram1500 (Oct 13, 2015)

Thanks guys i figured out the whole rise and run equation.


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## CTValleyRR (Jul 26, 2014)

Glad you got that sorted.

I still think you'd be wise to consider what cole, flyboy, and lehigh suggested, and make most of the depth of that bridge a scenery cutaway rather than an incline on you layout.


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