I am not using these but I need to find out how many feet of track it takes to go from table level to 3" clearance
That would depend on the steepness of the slope. (grade) Rise / run = grade. Grades over about 3% tend to be problematic. I am assuming a model here rather than a kids style layout.
A three inch rise at 3% grade would require 100 inches of track. You need “easements” at the top and bottom. An easement is a place where the slope gradually and smoothly changes from zero to maximum.
Use the “Search our community” box at the right to find a wealth of information on grades. Oh, and