why dont up or bnsf use a engine in rear ? how heavy is a 200 or more loaded container or pig train? wouldnt this speed up delivery time? i often see 3 or 4 , top engines ( 4400 hp) ,each on the point. never have seen this consist much for coal trains. 2 top engines in front n 1 on rear on coal trains thru illinois.
Different freight , different weight equals different power. The coal cars are short and heavy. The stack train has cars that are longer and lighter. The DPU is used to prevent the train from breaking in two due to stresses caused by the total weight of the train exceeding the couplers ability to stay in one piece. If you made a stack long enough to need DPU it would not fit in the sidings.At a GVW of a pig at 125,000 VS a coal car which can be 286,000 and the coal car is shorter. Half the weight and longer too. No DPU
CP does use a DPU or a couple of Stack trains from Eastern Canada to Vancouver.
The problem with DPU on a train made up with all or mostly trailer flatcars is the risk of derailment, and it only gets worse if any of the cars in front of the DPU are empty or even if there is a trailer but the trailer is empty. The reason that CP can use the DPU is that the trains are all Well cars, CP no longer handles TOFC only containers.
Is that because your sidings are long enough to handls trains longer than US or are these on regular lenght trains and needed because of terrain.
Its done for improved train handling. The trains chosen do no work between Toronto/Montreal and Calgary. Also of course in the winter it makes it much easier to maintain air brake pressure in the trainline during cold weather, finally of course there is no need for an EOT, but the gain from that is minor.
BN does. I have seen BN stack trains on their way from the San Francisco bay area running towards the father river canyon with two either c44 or ac4400s on the back. They either run them 5-0 (five in front no helper) or 3-2 (3 in front two helpers on the rear.