Re: Maximum grade for NG RR lines?

The grades on the Cass Scenic are often reported to be 10% or 11%, including in a number of published sources, but this is the result of people uncritically quoting old timers. Like fish stories, the climb gets steeper in the retelling!

The engineering drawings from the lumber company show the mainline grades to be under 8%. George Dieke and I were curious as to whether this was correct and we spent a day walking the steepest portions of the line with a 50 foot tape and a hand level. We found two or three rail lengths with an 8% grade, but that was the maximum until we reached the short final grade near the top of Bald Knob. This portion runs straight up the hill and does not follow the original lumber company grade. We found one rail length with a grade approaching 9%, but the average grade for that final climb was 8%. You can really hear the engines bog down there.

I am sure there were a few narrow gauge lines that needed to take single cars up temporary grades in excess of 10%, but the real risk is having a runaway if you slip the drivers for any reason. The coefficient of static friction is greater than the coefficient of sliding friction, so you can climb or descend a steeper grade than you can stop on if your wheels start to slip.

Michael Allen



Edited 1 time(s). Last edit at 12/26/2012 12:27PM by trainrider47.