rise/run

[arthur0109]

how much of a  run should i provide to reach a 3" grade rise?

[jward]

it depends on how steep a grade you want. grades are expressed in percents, which is a ratio of  rise to run, a 1% grade is 1" of rise per 100" of run. 4% is about as steep as you'd want to go. that would take 75" to get your 3" of rise. better is a 3% grade, which needs 100" of run. if you are using sectional track, this works out to about 1/4" rise per full section.

[ebtbob]

To flesh out Jward's advice,   in 100 inches which is basically 8.5 ft,  a 3 inch rise is a 3% grade.   in 200 inches which is basically 17 ft,  2%,  and in 300 inches which is basically 25.5 ft would be a 1 % grade.

Certainly hope I did my head math correctly.

[J3a-614]

Another thing to keep in mind is that you can sometimes split the rise between the two lines--in other words, the lower track descends as the upper on ascends.  This can be used to reduce the grades to half or so, or alternately, to cut the run in half for a given grade.