The original trestle at Humason was built with the bents in the stream bed. Abuttments were wood and were rebuilt as such, to closely resemble the original structure. There have been no erosion problems there.
The problems farther up the line in the uncleared, ungraded section were due to the ditches filling up with soil. The water sought the easiest way out, which in one case eroded the ROW.
The slide that occured was from about the same reason. Accept the trees were weighing down the bank and once they got so heavy, they just took off. The water had seeped through just under the surface, making the bond that the topsoil had with the clay slick. Water was still dripping into the slide a week or so later when I saw it.
If the railroad had made it to either of those locations before the washouts happened, they never would have. With proper ditching, The ROW should last a long time. Barring of course some astronomical storm.
