Building Grades for Model Railroads
Very few railroads had the luxury of being built on a completely level route. To climb hills and mountains, railroads need grades. A lot of engineering and planning goes into grading a right-of-way to ensure that trains can ascend and descend efficiently and safely.
Grades add visual and operating interest to a model railroad. Installing a grade is not difficult, but it does take a little planning.
How Steep is Too Steep?
One of the first questions that comes to mind with any grade is how steep it should be. Grades are measured by the rise over the run in terms of a percent. So a 1% grade will rise one unit of measure over a run of 100. On the prototype, a grade of 2% is considered steep for a mainline.
Branch lines, industrial spurs, logging operations and other lines where tonnage and speeds are reduced may see grades of as high as 4 to 9%.
Model trains are much more tolerant of grades. Our trains are generally shorter and weigh much less, so the forces of physics are minimized but still present. Grades of 2 to 4% are usually not a problem for most model trains. Above that, you may have to put some tight limits on how many cars your engines can pull. Another consideration is that grades steeper than 4% usually look too steep to be realistic even if they are manageable.