I understand the concept of DPU’s on long, heavy, Class 1 freight trains. Is that the only place they typically used? Today, I saw the Dakota & Iowa rock train pull through town, with 2 units on the head end, one on the tail.
The D&I is an old Milwaukee Road line, that runs about 85 miles. from a quarry in Dell Rapids, S.D., to interchange with BNSF, UP, & CN at Sioux City, Iowa. About 99.9% of it’s freight is pink Sioux quartzite. From the quarry to Sioux City is all downhill. The trip back, going uphill is all empties. I say uphill, but in reality there is only one hill, in Sioux Falls. It’s a doozy, but everything else on the line is pretty much flat.
Would a small railroad hauling one or two rock trains a day invest in DPU equipment? The locomotive on the tail was running, but where I saw it, it was hard to tell if it was pushing or not. All but one of their units are re-cycled geeps, including some ex-Milwaukee Road units. Was it just a coincidense, that this unit was tagged on the rear? If they were just hauling it home, why would it be running?
Murph – I expect what you saw is a push-pull operation where a locomotive is tagged onto the rear of the train so that a reverse move can be made at some point without having a man ride the rear of a car for a long distance, or a runaround move (there may be no runaround track and constructing one is not cheap). This is actually fairly common for rock moves because often rock moves in large quantities (justifying a dedicated train) but for a short period (not justifying building a runround track or straight-rail connection at the end with the otherwise blind shove).
The locomotive might have been running but I doubt it was under load unless DAIR has suddenly invested in DPU on GP20s (doubt it!) or a man in the cab. It was running because you don’t want to shut down a locomotive in cold weather unless it has a hot-start to avoid having to drain it and refill it later, plus restarting an old locomotive is always a bit of a gamble.
I don’t see DPU broadening its application beyond big, heavy, bulk trains; big, heavy manifest trains; or big, heavy double-stack trains; any time in the near future, not on any widespread basis. There are often a few exceptions.
What are the track configurations at the load-out, at at each of those interchanges - and to get to each of them ? If there’s one or more switchbacks - or even if all the sidings are double-ended - I’m with RWM’s explanation of using the unit on the far end mainly for operating convenience and speed - to avoid the cut-off, put the markers and FRED on, run-around - including about 4 switch throws, hook-up, test the air, etc. just to change directions. This way, it’s just take out the reverser handle, maybe* walk the length of the train, plug it into the unit(s) at the other end, climb on, and go.
(* - or not, if one guy drops off the front end and waits until the rear comes by, and then climbs on that)
Here in the Allentown - western Lehigh Valley ¶ area NS has a daily (or more often) local of from 10 to 30 cars (typ.) that almost always has 1 or 2 units on each end - typically 4-axle GP38’s of some version, but I’ve also seen SD40’s and other big power. It runs west from its Allentown terminal about 15 miles to Alburtis, where it reverses onto the C & F Secondary for about 8 miles towards its terminal at Chapmans Yard, and then reverses again for a couple miles to serve the industries in the industrial park that’s clustered around I-78 and PA Rt. 100, so you can see how much time that saves going out (and as much coming back in). I’m pretty sure that not all the sidings in there are oriented the same way, so aside from those 2 “main line” reverse movements, there may be others in the switching operations. It would take an man experienced in such things (which I’m not) to tell you how much time that saves, but I’m sure it’s significant - NS isn’t doing that just to exercise the locos. Plus, at the Alburtis move, it saves having to run through 2 signalled cross-overs and tie up the other main line (it 2 main tracks there) while doing that.
The weekly eastbound Railex perishable trains both begin life as DPU trains, with anywhere from 30 to 70 reefers. We have trains to Global 3 from the other two Globals that use DPUs–some are long, but some surprisingly short. I suppose this could be for ease of power placement at the opposite end of these runs, and I have no guarantee that those Global trains are actually running any differently than the rock trains.
Carl, the Railex trains are heavy, and the hp/ton is unusually high in order to meet the schedule. If you tried to put all that power on the pointy end you would tear them in two. Even on days when the train runs light you would want to DP them because you develop service consistency that way.
I watched one accelerate out of Roseville a few weeks ago running 3x1 with 50 reefers; it took off like a passenger train. Impressive!
Often, trains are set-up as DPU even if the train is short or light upon leaving its initial terminal because it is going to pick up en-route and require the DPU later. But few terminals will DP a train if they don’t have to; it’s such a pain to hostle the power to the blunt end.
Out across Iowa we’re seeing more DPU on intermodals. Some short, some long. The longer ones used to be conventionally operated so their lengths didn’t grow that much, just one (or sometimes 2) now on the back end.
The MPRNP/MNPPR freights are almost always DPU and usually 1 and 1. Once in a while mty grain trains are coming up from the south DPU. One of those had to be conventionalized at the junction with the grain line to continue on to the elevator. I think that was done because of crew qualifications rather than operating limitations.
The destination for all that rock is a storage area in Sioux City. I believe that area was originally a Milwaukee switchyard, but many of the tracks are gone to make room for the rockpiles… .
Usually the train is powered with with some combination of the D&I’s SD45’s. However, I have seen the engine on the rear (usually a GP9), and it sounds like it is just idling along. I’ve thought that perhaps they keep a switcher in Sioux City and from time to time need to exchange it with one from their quarry at Dell Rapids.