Klamath Falls to Bly
This line was initially constructed in stages between 1917 and 1929, mainly for the benefit of Weyerhaeuser Lumber Company. Changing market conditions for wood products led to this line's abandonment in 1990. Part of the route is now a trail.
The route includes two switchbacks to help navigate the mountains in the area. The mountain on which the switchbacks are located is appropriately named "Switchback Hill".
Thanks to Craig Bass for contributing information.
The Oregon, California, and Eastern Railway Company was built by a railroad promoter named Robert Strahorn. He had plans to build to Silver Lake, Oregon and from there to Bend, Burns, and Lakeview. He only managed to build to Sprague River before he sold the railroad to Southern Pacific, to the outrage of Klamath Falls supporters who wanted a competing railroad to SP. The ICC force Southern Pacific to sell a half interest to Great Northern and to build on to Bly.
The switchbacks on Bly Mountain were intended to be temporary, until a tunnel could be bored, which never happened. Weyerhaeuser bought the OCE in 1975 and double tracked the tail tracks of the switchbacks. Their log trains had two cabooses, one in the middle and one at the end of the train. At the switchbacks they would cut the train behind the first caboose and take that half through the switches leaving it on the second tail track. Then they went back to the rest of the train, ran it through the switches, and coupled up to the half left on the tail track. The caboose that was in the middle ended up on the end of the train after going through the switchbacks.
"Railroad Logging in the Klamath Country" by Jack Bowden has a very interesting section on the OCE.
I understand it was the only double track switchbacks in the country. Two mainlines, NP on Stampede and GN on Stevens, each had many switchbacks but all single track, some great hiking up there. I enjoyed riding an excursion train on this RR shortly before abandonment.