Interesting you whould mention the Siskyou Line. When Railamerika bought this place in 2003, the crews here were using the D&RGW,SP,UP method which I discribed above. A few months into it here RA announced that there was no need to use retainers, that someone would be coming out from the Central Oregon & Pacific (RA's outfit that runs the SP Siskyou Line) to show the SLRG folks how its done.
They did, and piled one up that winter.
Thier system was put 10-12 lbs under the train at the summit and control the speed with the dynamics down the hill. This does work if you have 100 percent extended range dynamics brakes which are effective at 10 mph. The power that RA leased for the SLRG did have extended range dynamics. When Iowa Pacific took over, the units RA had went back to the leasing company, IP bought X-Amtrak F-40's that did not have extended range dynamics. There were 2 other leased engines on the property that did have extended range.
I came out here shortly after IPH took over and were still running RA's units, and learned the "1 set and dynamic brakes" method. It does work, you use more dynamic braking (throttle 6 about 600 amps) which is harder on the track. I also got the feeling I was trying to balance an elephant on the head of a pin keeping the speed at a nice steady rate.
We also use the "15-15 Rule": If you get going 15 mph or set more than 15 pounds of air, plug it and get it stopped - now. On a typical trip you were already 12 pounds into the train, running pretty hard dynamics. It left very little margin for error or an over-active flange oiler, ice, etc., before you got in trouble. One used as much sand going down the hill as one did going up. Using the short cycle method allows you to use less dynamic brakes (keeping more in reserve) and less air (keeping more of that in reserve) which greatly increases the safety margin and reduces track damage. The cost is we stop at Fir to put up the retainers and again at La Veta to knock them down. The average delay is about 15 minutes.
I think the runaway they had here under RA was caused by ice forming in the brake pipe as it was bitterly cold night. By not keeping the air moving through the brake pipe by constantly setting and releasing the brakes, ice was allowed to form. I don't think it gets as cold on the Siskyous as it does on La Veta.
It is interesting to note I talked to Jim Pearce here in Alamosa about this and he told me they tried and used the "1 set and dynamics" method for a while and came up with the same conclusions we did.
