GP 40 posted:Concerning Dynamic Brakes and this incident. It is important to understand that, assuming these are 3 modern AC locomotives, each equipped with Extended Range Dynamic Brake, they should be capable of generating around 115,000 - 120,000 Lbs. of retarding effort apiece. Total of all 3, under the best of adhesion conditions, would be somewhere in the neighborhood of 340,000 to 360,000 lbs. Dynamic Brake retarding effort (in their most effective speed range of 6-23 mph).
A 112 car loaded grain train would weigh somewhere around 14,500 -15,000 TONS (30 million lbs.). Bottom line is that this consist would not have been capable of maintaining any speed descending this type of grade using Dynamic Brakes alone. It would be necessary to supplement the Dynamic Brake with an air brake application in order to keep the retarding forces sufficient to control the train at the desired speed. Blending an air brake application along with the locomotive Dynamic Braking effort would be absolutely necessary to slow or stop the train on this heavy of a downhill grade.
Severe sub-zero (F) temperatures can do strange things to the air brake train line.
Employee statements from all active participants, (crew, any local managers, and control station), any recordings from radio conversations, position of the controls on the controlling locomotive, event recorder downloads (from all 3 locomotives) and post accident mechanical inspection of the equipment, should provide all the information needed to understand what events occurred resulting in this accident.
The $64 question is "What will be done to prevent it from re-occurring?"
GP40
Thanks for posting this. About a decade ago the BNSF ran west bound loaded grain trains over both Stevens and Stampede Passes. One of the reasons they did so because they had been sending Puget Sound grain trains on the lower grade NP/SP&S route via the Columbia River for so long they were running out of guys who had run heavy tonnage unit trains over the mountains.
Three Dash-9s, I believe all or mostly DC locomotives, could handle a 15,000 ton train over the low grade route and get the empty train back over the mountains at bout 15 MPH. Five units were assigned to get the loaded grain trains over Stevens and Stampede in a 3x2 head end and mid train DPU configuration. AND a two unit manned helper set was added on the rear for the 2.2% portions of the trip. While some early trips were made cutting the helpers off at the top of the grade most trips were made with the manned helpers staying on until the BOTTOM of the 2.2% grade at Skykomish or Lester. This was done so the same dynamic breaking capability was available going down as there was tractive effort to go up.
I understand that the CP has been running loaded unit trains with 1x1x1 DPUs down Kicking Horse Pass for a number of years. Based on what I have read here and heard from BN people that scares me. With only three units worth of dynamic breaking coming down Kicking Horse Pass if you lose the air and accelerate to 5-10 MPH you ARE going to continue accelerating and derail before you make it to the bottom of the grade.
