Former CP (Soo) engineer here. These are my thoughts after having read the special instructions for handling trains over this grade. The entire train should have been tied down per CP rules. (This is not a new rule. Special instructions from 20 years ago state this.) This should have been done by the original crew regardless of hours of service. Canada may be different but I really doubt they are forbidden from working past 12 hours to tie down a train when conditions require it.
There is talk of handbrakes and cars with truck mounted brakes. I see some of those cars in pictures of the wreck. The cars lettered CP Rail with SOO reporting marks have these. (Later cars with the CPR herald do not have these)For one, these do not brake as well in my experience and secondly the handbrakes (immaterial in this instance but they were brought up) only apply on the B end truck on these cars. Truck mounted brakes are part of the reason so many cars need to be tied down per special instructions here and anywhere else on the railroad as they do not want a judgement call to come into play. Much like locomotive hand brakes, which only apply the brake to one axle, hand brakes on truck mounts do not hold all that well.
I do not know if the crew being relieved was there when the dogcatch crew arrived. Have not seen this stated anywhere. If they were, there should have been a job briefing informing the relief crew there were no brakes on the train. And at that moment the conductor and student should have started spinning brakes. If there was no crew to get a briefing from there should have been a message on the control stand stating the condition of the train.
Either way, it has been reported the relief crew had reservations about taking this train so this tells me they knew the status of the train. In emergency with no hand brakes. And obviously they were all on the locomotive when it started rolling. In that situation I am getting off that train RIGHT NOW as the engineer had zero options to stop or even hold back that train. In those temps even with a 1+1+1 DPU setup there is no way he is getting enough air into that train fast enough to get it into emergency again. And even if he did the application would not be as strong as the first as the reservoirs would not be anywhere near fulling recharged.
Also, unless they have changed them in the last few years, CP AC units are set for max 100K dynamic to reduce in train buff forces. (Interesting side note, CP SD40-2's were set at only 45K max dyno for the same reason as they ran them in 5 unit sets quite often. After the first few orders of AC's they were turned up to the normal 60K as they were no longer used in big sets in the mountains.) Even if that UP unit was set higher there was not nearly enough dynamic to hold the train.
I recall someone brought up dynamic holding and dynos dropping out in an emergency application. CP units were originally set up to drop out the dynos when the train went in emergency. This was changed to dynamic holding meaning they would still work for a time even after the PCS tripped due to losing the air. However, as I recall, this did not hold forever. Meaning a stopped train with the PCS tripped would not have dynamics. Or if the engineer put the throttle in idle then went back to dyno he would not have them. One would have to release the brakes to recover the PCS giving you dynos again.
Poor braking prior to the emergency stop could possibly be a combination of snow/ice on the brake shoes and the number of truck mount brakes in the train. It's quite possible in looking at the profile of this line the engineer never used the train brakes after leaving Calgary. Or if he did it wasn't enough to really clean off the shoes. Trains don't stop worth a damn until one gets some heat into the brake shoes in the snow and going upgrade prior to cresting the grade the original crew would have had no real chance to clean them off with a minimum set. Not positive this is the case, but it does fit the poor braking reported.
Just speculating, but worst case scenario is the train sitting there for two hours in -30 temps, throttle in idle, pcs tripped and likely snow/ice on the brake shoes with no handbrakes set. When it started moving there was no way to stop it. The crew should have got off right then and there and watched it go.
