Out here in our area, South Central Kansas; I have noticed recently, on several Import/Export Container Trains the presence of mid-train DPU's.
This has not been something that had shown up (noticed?), until recently. Generally, BNSF has used head-end power ( multiple units 3 or 4 +) going Eastbound. DPUs only seemed to be on the Westbound moves of Export-type containers. THe Domestic Container Trains seem to run all their power on the head-ends, in both directions.
The Mid-train DPU's seem to be on longer trains (10,000+- ?). The last couple I observed were 3 and 4 units on head-end, two in mid-train DPU, with a single unit on the rear DPU.
I was just wondering if this was an 'experimental use' , or was this showing up in other areas of BNSF ? UPRR seems to favor just a single unit in DPU on their trains, while BNSF always seem to have a pair, as DPUs.
Mid-train DPU's (slaves to us old-timers) used to be standard practice. I would think that the time involved in placing DPU's mid-train may be one of the main reasons that DPU's are usually placed on the rear of the train.
Mid train DPU's would help lessen the chances of stringlining the cars, especially on very lng rains like the ones that you are talking about.
Mid train DPUs may not be as difficult as once tought. Imagine ABC intermodal yard can hold 8000 ft trains on 8 tracks. Place 2 or 3 locos on one 8000 ft set of cars and place 2 locos on another set. Back first set onto second set brake test may have already been done on yard air confirm EOT and DPU set up and off you go. Only change crews and do 1000 mile check.
Combining / separating could also be done with two trains coming from / to different yards.
Another help is that with the present surplus of locos any train built this way would almost always have a higher HP/ton increasing fluidity and train speeds.
blue streak 1 Mid train DPUs may not be as difficult as once tought. Imagine ABC intermodal yard can hold 8000 ft trains on 8 tracks. Place 2 or 3 locos on one 8000 ft set of cars and place 2 locos on another set. Back first set onto second set brake test may have already been done on yard air confirm EOT and DPU set up and off you go. Only change crews and do 1000 mile check. Combining / separating could also be done with two trains coming from / to different yards. Another help is that with the present surplus of locos any train built this way would almost always have a higher HP/ton increasing fluidity and train speeds.
This the line of thought I had had myself. Out here, coming off the BNSF' Southern T-con they do seem to run large numbers of very long trains. I have no way to measure those ( except to count the cars). The placement of mid-train power would seem to solve a couple of problems for the railroad. Speeding up handling issues ( air, setting-out purposes(?). Having units already in the consist at predetermined points would make'breaking down' a train at a terminal to allow the trains to continue on to smaller facilities (?). Not to mention, the ability to handle the trains across the railroad in terrain that has a rising and falling track profile(?)
I don't know about BNSF practices, but on the UP the DP consist must be within 8500 feet of the lead consist. So if the train is longer than 8500 feet, measured from the last engine in the lead consist, the DP will be mid-train. Although mid train may not be actual middle.
Jeff
jeffhergert I don't know about BNSF practices, but on the UP the DP consist must be within 8500 feet of the lead consist. So if the train is longer than 8500 feet, measured from the last engine in the lead consist, the DP will be mid-train. Although mid train may not be actual middle. Jeff
I seem to recall the 18K foot intermodal train UP operated from Texas to the Left Coast had 2 sets of mid-train DPU's as well as a rear end DPU.
Never too old to have a happy childhood!
Our current instructions allow 18K foot trains with a mid-train and rear end DP, and a 6K foot restriction between the engine consists. Without the rear DP, train length is restricted to 15K feet with a mid-train DP equipped with an EOT repeater. Without the mid-train DP, all engines up front, length is restricted to 10K feet.
There are a couple of exceptions allowing 10K foot trains with a rear end DP only. The exceptions are for some intermodal and autorack trains that are entirely made up of certain car types.
Without a scanner, I am pretty limited to just observation. Having just resettled on a BNSF line (Emporia sub-Main 3) we have a lot more train traffic just off the back fence. The multiple DPU seem to be specifically limited to Import/Export Container trains. The Domestic trains generally, run all their power on the head-end. The only trains that seem to have DPU's are the grain trains and grain shuttles. BNSF seems to favor a protocol that uses two units in DPU when they are present. Head-end power is generally three units, occasionally four units. But on several occasions I have seen set-up with as many as eleven units on the head-end ( was not close enough to them to hear, but my guess the majority in a power set like that is that with the exception of three, or so, head-end power most are DIT. (?) I am still amazed at the number of trains that cycle through the Mulvane area, and the diversity of power used around here.
No such thing as a high HPT on CN. If it's high, you're throttle restricted or isolating engines.
10000 feet and no dynamics? Today is going to be a good day ...
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