Saturday night I waited in DeKalb IL for a container train to pass. I was quite surprised to see a helper engine following it up.
Is is becoming common to have helpers on trains in what is essentially flat country?
It’s called “distributed power”. There have been a number of threads on this subject here.
Yes, it’s definitely becoming common, especially on the western railroads. On the UP line you mentioned, you used to see the DP units only on coal trains. Now they’re common in intermodal trains (sometimes midtrain instead of at the end) and some manifest trains, too.
With distributed power (all under control of the engineer at the front of the train) it’s possible to haul additional cars with the same amount of power, because slack is being controlled better. Also, initiating brake applications from both ends of the train makes the application quicker, and should make operation safer.
Do a Forum search for distributed power, and you’ll get plenty of facts and opinions.
In cold winter weather it also helps keep sufficient air pressure thoughout the train. The air hose connections can have minor leakage, especially in bitter cold weather, making it a challenge to maintain sufficient air pressure at the far end of the train. A DPU solves the problem by providing a second source of air. Some railroads used air repeater cars (containing an air compressor and related control equipment) to combat the problem but these have mostly been superseded by DPUs.
John
As Carl can attest, it is very common now on UP trains in the western suburbs along the old CNW line.
We see this a lot up here in Manitoba on CP’s lines, mostly on intermodal trains, but occasionally on long grain trains. Most often, there will be a single or paired power unit in the lead with a helper unit about 2/3 of the way back on the intermodals and at the end of the train on the grain unit-trains.
I was chatting with the maintenance supervisor for our local sub and he informed me that not only is distributed power better for slack management, but that there is also an improvement in fuel consumption over having all of the power at the head end. Granted, not a major improvement, but when you run thousands of trains for thousands of miles, it all adds up.
Mike
Thanks for the answers! One more question; DP control is radio, how does it cope with things like tunnels and steel-frame bridges?
Just like a fred you lose comm for a bit then it will come back.Well hopefully anyway.
BTW ( edit time) I cant find my BNSF stuff and I am not going to go get my bag out of the car to check CP rules. But I have never heard of the brake application coming out of the DP as well.Someone want to eiter refresh my memory if it does or tell me if I am right when I say “No I dont think so”?Old age is creeping in on me I guess as I used to condition DP sets on a daily basis.I dont recall the dp unit allowing air out of the brakepipe it does however add air to it after a release.Maybe I am getting senile I havent run any DP stuff in 2 years but the rumor is we are going to start here again someday.
In southeastern Kansas on the UP through Parsons,Ks. ( southbound, pretty much all traffic). UP in that low rolling country uses one unit of the rear of practically all trains) in DPU. BNSF run through coal unit trains use mostly two units in DPU on the UP routing.
Here in Southcentral Kansas on the Transcon, I would hazard an unscientific guess, about half use two units in DPU. It seems to be most of the longer trains, definitely run two units in DPU. And some of the grain train shuttles will run a couple of units on the point when loaded and a single in DPU on the rear, and when they are returning empty to reload, the run back with the single unit on the point and the pair of units in DPU on the rear of the returning train.
Interestingly, I’ve noticed practically all the container trains run three or four units on the point, and some of them have DPU units on the rear as well, those trains will have container cars as well as TOFC cars. Solid container trains seem to have only head end power more often than they operate in DPU. Another thing is that most of the heavy power moves (multiple locomotives, working and dead in tow) are always eastbound. The most locomotives I’ve noticed was a dozen recently and most of the time it’s eight or nine on the point.
As for the terrain here it is pretty much flat until traffic gets North of Newton and North of El Dorado headed to the East.
The UP (former C&NW) Overland Route isn’t flat.
RWM