I cant say that I have seen

I cant say that I have seen anything other than Coal and Stack trains with DPU. And of those, I have only seen coal with midtrain, and that was in the Moffat Tunnel area of Colorado, never out in any "non-mountaineous" areas.

For the railroads, the rhyme and reason to when and where to add distributed power is a complex and exact mathematical formula, factoring in ruling grade, train priority, Tons per operative brake, overall train weight, and others Im sure.

On the UP, the coal trains we get here in Southern Illinois have 2 up front and one in back. These trains come from Power River basin. They need to pusher there, and they need the pusher here, but I think they could probably get by with just the 2 in the Nebraska to Illinois portion. But it is probably more efficient to leave the locos together on the train so not to have to make the brake pipe tests any longer time wise when cutting in and out the extra engine.

So they just leave them together as a solid consist from there to here, and back again.

Is this something you would like to model firmly as the prototype does, or could you run midtrain and end-of-train DP and just make if "look" right?

Steven

DPU

Grain and Coal come to mind, but are there others?

What era are you looking at?  Pre -mergers SP and ATSF used both mid and end of train helpers on Tehachapi ,sometimes even on the same train. A typical SP train might have had 4 on the front, 4 somewhere near the middle and if long maybe 1 or 2 on the rear. I've seen as many as 6,6,and 2 on long heavy trains. I haven't been to Tehachapi recently so don't know what UP and BNSF are pulling the hill with these days.

Mid Train on CP

I've seen mid train and end of train power in Mixed Freights on CP in Winnipeg. I was quite surprised the first time I saw it.

More examples

Just to be different, the D&RGW ran mid-train helpers over Cumbres Pass back in the NG days.  The reason was that the bridges (Lobato, at least) could not handle the weight of two locomotives at once.  I'm not sure if the new bridge can or not.

As for 21st century operation, on NS we use DP on coal and intermodal trains, but I've only seen them on the rear, never mid-train.  When they work, they are a dream to run.  When they don't (which, in typical GE fashion, is not unheard of), you have a train with half the power it needs.  If you're lucky you can limp to someplace where mechanical forces can get to the train and try to solve the problems.

I remember in the DP training that they mentioned the possibility of running mid-train helpers, and then splitting the train into two with each section going a different direction.  I can see the operational benefits of that, and I look for it to happen in the coming decades, but so far I've never seen it done.

UP here in Chicago also DPU's

UP here in Chicago also DPU's a couple manifest trains each day as well, but as stated I have no exact reason why or when it's done.

DPU Vs Helper

It may be a language issue, but isn't a helper engine is used on a small stretch of track (such as a ruling grade) and a DPU part of the motive power for the train since its formation to its destination (as in a MU consist)?

Here in Brasil Estrada de Ferro Carajás uses 3 ES58ACi (or 4 SD-70) in DPU on its ore trains with a C44-9 and a SD-40 MU as a helper consist for its two helper districts - therefore i got the notion of helper being different of DPU.

It may be a language issue, but isn't a helper engine is used on

     I think you are correct in your interpretation of the terms. Here in the USA  the DPU term is a modern era term as far as I know. In the old days it seems that they just called them helpers or pushers. SP experimented with radio controlled helper units back in maybe the 1970's or 80's but they didn't really take over the pusher jobs as I saw crewed helpers for many years after.Apparently the early radio controlled locos had problems with command signals in tunnels etc. I can't recall those old units being referred to as DPU ..dave  

DPUs

Prof, it would help to know what years you are looking at. The placement of additional locomotives has changed quite a bit over the past half-century.

In Nebraska and in the Columbia River Gorge, UP's distributed power is generally placed at the front and rear of the train. In the Gorge, the local one-of-everything haulers tend only to have power on the head end, but runs like the Canpotex potash covered hoppers (up to 120 cars now) will have two or three on the front and one or two on the back. The placement gives them better control of in-train slack, and reduces terminal time adding and dropping power.

Someone else can comment on stack trains -- I simply can't remember and it's been such a damp, gray winter in Oregon that I haven't been out to look at trains.

In a model situation, overpowering with locomotives back in the consist is a recipe for accidents. If your head-end power is sufficient to haul the train, consider adding a dummy or a sound-only locomotive to represent the DPU.

Midtrain DPU

Just for the record, I'm talking about the technical aspects of DPU, I do not know firsthand about DPU anywhere but in Brazil

Midtrain DPU would be used in long unit trains, as a way to reduce stress on the coupler. Although AAR knuckle coupler does bear much more draw bar force than other couplers it does limit total weight.

With DPU units in the middle of the train you relieve the coupler stress in the lead cars and allows for a longer and heavier train. However, it has the drawback of having extra switching to put the DPU units in the middle, therefore would be likely that this setup would be used in a long routes or in situations where cars would not be added or dropped very frequently (such as a ore carrier, carrying the same cars from mine to unloading facility and dropping the cars only for unloading)

If the only reason for using a DPU unit is to avoid turning the engine or running it around and weight is not a issue then the units would be placed at the front and back only.

Another bonus for the DPU is that by reducing draw bar force you also reduce many other factors, such as wheel flange wear, track wear and so on, reducing maintenance costs and increasing revenue miles for the equipment. It also puts extra brake sets in the middle (and/or the rear) of the train, so application of brakes is more efficient

Grain unit trains can be loaded and unloaded without uncoupling the locos, so it would be safe to assume that (if the elevator has enough capacity to load a whole train in one go) the midtrain DPU could be used and the locos and grain hoppers would be a semi-permanent unit.

Mid train vs front & rear, DPU vs Helper

 A helper is when engines or locomotives are added temporarily to a train in order to get it over a pertion of the railroad.  Normally a grade territory.

DPU is a technique of adding one or more remote radio controlled  consists in a train.

DPU can be used as a helper or as part of the normal consist.  The train takes 3 units to move it.  Conventional would put all 3 on the head end, DPU would put 2 on the head and one on the rear.  Same engines, they are just configured differently.

In the "grain states", which I assume is Nebraksa, Iowa, the Dakota's, and Kansas  DPU's could be virtually any type of train.  Virtually all coal trains are DP'd.  Many grain trains.  Longer stack trains.  Heavy drag manifest.

BUT......

Virtually none of them on the UP will use midtrain DP's.   I can't remember seeing a single midtrain DP on the BNSF going through Lincoln, NE either.  The only places that mid train DP's are used on the UP are the extraordinarily long trains 12,000-14,000 ft and above or train in very severe grade territory (the Blue Mountains, the DRGW west from Denver).  99.9% of the DP's in the "grain states' will be front and rear, not midtrain and the majority of that will be bulk (grain and coal).

You will sometimes see the

You will sometimes see the midtrain DP on stack trains and manifest trains mostly. They do this because say the yard where the train terminates has 6k foot tracks, and you are bringing in an 11k foot train you can make the double and then make a simple move to gather all of the power back into a set without making a move back around the train.

I remember in the DP

I remember in the DP training that they mentioned the possibility of running mid-train helpers, and then splitting the train into two with each section going a different direction.  I can see the operational benefits of that, and I look for it to happen in the coming decades, but so far I've never seen it done.< <

The BN tried this with coal trains out of the Powder River Basin back in the mid too late 80's, with limited success. It was quite a site to see one of those trains chugging up Crawford hill (western Nebraska). Five units on the point, five units in the middle, and four helpers on the rear. Generally it was 4/5 units on the head end and a pair of helper units on the rear with 115 cars. The problem was running 230 car trains on a railroad built for 115. This caused problems on the road and in Alliance, Nebraska yard. Most all coal trains east (between Alliance & Lincoln) used 2/3 engine consist. Engines had to be switched regardless if the train was split. After building longer holding tracks at Donkey Creek (Wyoming) and Alliance the BN gave up on it and went back to 115/20 car trains.

Jerome, Oklahoma City

UP/BNSF Feather River Route

There are not many mid-train DP trains on the Feather River Route.  BNSF has run a few 14,000 ton grain trains with mid-train DP.  The extra power is mostly for the 2.2 percent grade on the High Line from Klamath Falls to Keddie.  Down the Feather River, it is the famous 1 percent grade.  UP grain trains are typically 2 units up front and 1 DP unit on the back.

Some trains have been run with rear end DP simply because an ETD was not available.  The advantage of running DP on the back is that it takes care of the ETD requirement, and is easier to switch in and out of the train.

As Jerome notes, longer DP trains are "non-clearing" i.e. they do not fit in most sidings and yards.  While railroads experiment with the technology, they come back to what fits.  The DP technology will allow for up to 5 consists distributed through the train, but I have never heard of more than 3 being used.  Linking DP consists is a complex and time consuming process. 

DPU on NS

In the last couple months, NS is starting to run oil trains destined for New Jersey and Delaware city that originate out of the midwest (originating on BNSF) with DPU on the rear at the request of BNSF. From what I hear, they do not require additional helpers over horseshoe curve, saving time. They also do not have to stop the trains when they enter NS territory in order to strip off the BNSF DPU power. Again, another time savings. This is all due to a huge spike in oil shipments, and a lack of tank cars in the fleet. Turning the cars in a timely manner is the most important driver of using DPU in the case, IMO.

NW Louisiana observations.

NW Louisiana is relatively flat. The UP coming in over the Red River usually has two on the front and two on the back. Makes me think of a push/pull operation. Occassionally there are more engines on the front.

On the KCS, running behind my house, I never have seen an engine on the rear.  I have counted 6 engines on the front at times.  However, I did see a ragged looking KCS yard switcher once in a train that was between cars. It was in pretty bad shape. It might have been a dead  unit on its way into Shreveport for a rebuild or to be scrapped.

Den

Dead engines

If an engine is handled anywhere in the train except on the head end (with the exception of DP and some air repeaters that the BN used for a while, I think), it's almost guaranteed to be dead.  Locomotives are supposed to be handled in a solid block, so that the MU connections and especially the brakes can be operated properly.  While it is possible to set up a locomotive so that the brakes run much like a box car's, there will be no brakes at all unless the engine is running and charging the main reservoir.

There is a special valve designed to allow train line pressure to charge the main reservoir (called, appropriately enough, the dead engine cut-out cock), but if that valve is opened the engine must be handled with a spacer car, to prevent accidentally connecting the main reservoirs of the working engines directly to the train line.  Thus, if the engine is not on the head end or DP power, it's probably dead.  And as far as I know, ragged yard power has not been converted to DP yet.

Midtrain helpers

Here in Helper, Utah where we got our name from the D&RGW helper locos, the Utah Railway, UP, BNSF, and the now missing, sadly, D&RGW all use various combinations of helpers and DPU's. The Utah Railway currently pulls 104 cars of coal up Price canyon to Soldier Summit, approx. elev. 7450 ft. Five SD 50's on the point, 76 coal cars, six SD 50's and the trailing 28 coal cars. They remove the help just shy of the summit and then the train continues on to the Intermountain Power Project at Delta Utah. The helpers come back to the Martin yard light, about 90 minutes round trip. The UP, on some trains will have four AC 4400's on the point, about 75 or so coal cars, three AC 4400's helping and then another 25 to 30 coal cars trailing. They run to the summit and break the train and locos come back light to Helper yard. UP also runs DPU's on coal trains. Sometimes there is two locos on the point, two locos midtrain and two locos on the rear, splitting a 94 car train in half.

UP also runs helpers at the approximate 2/3 train length both ways over Soldier Summit on mixed freight trains. Usually three AC 4400/AC 6000 combinations, sometimes an SD 90, or ES 4400 AC. Frequently they will have 1 or 2 DPU's on the rear of other freight trains. Again, in both directions over Soldier Summit.

BNSF also runs 1 or 2 DPU's on the rear end of various mixed freight trains going both directions over the summit.

D&RGW used to run 84 car coal trains split at the approx. 2/3 length with four SD 45's on the point and various mixtures of GP 40's, SD 40T-2's and SD 45's helping. They also ran all varieties of mixed freight with all varieties of midtrain and end of train helpers. F units, GP 7, 9, SD 7, 9, GP 30, 35, 40, then SD 40T-2, SD 45 and SD 50's. How I miss seeing all of those combos.

But for now, in my opinion, there is nothing like standing trackside next to six SD 50's screaming at full throttle and blazing by at 15 MPH helping a Utah Railway coal train up the hill. AWESOME display of horsepower. My wife even likes doing that, now that she has been introduced to trains.

When will somebody make a decoder with that sound? EMD's working their guts out!!

BM

Kansas City Southern

The KCS uses helpers to get freight trains through the Ozarks (Rich Mountain); with a 1.8% grade.  They used mid train helpers and purchased radio controlled SD40-2 (Snoots).  They now use helpers on the end of the trains.

Southern Railway ran mid train

Southern Railway ran units mid train, called radio trains, in the 70s and 80s maybe even 60s. Mostly coal trains. The Belmont Coal train ran as a radio train over Saluda Grade, the steepest mainline grade in the USA 5 % at one point. The radio trains also operated over the Loops between Old Fort and Asheville NC. When the Saluda line was open both directions east or south from Asheville involved grades and SR ran the radio trains over those routes.

I can't remember if a merchandise train ever operated with the mid train units. SR had special cars that carried the radio control equipment and ran just next to the mid train locomotives. The locomotives set up to be lead could be identified two ways, one was black on white number boards as opposed to the standard SR white on black, and the other was two firecracker radio antennas instead of one. The first radio control cars were converted from old FT b units. 

It was a site to see three SD40, 40-2s or 45s on the point and two or three more mid train. 

Bill Michael

West USA

My layout is based on the Northern Californian and Oregon area in modern UP days. Videos I have (unfortunately I live 1,000s of miles away) of trains there often have mid train or rear DPU's. From what I've read rear units were often used when manned, where radio problems stopped reliable control, once that was solved more mid train unmanned DPU's were used. They are used on all sorts of trains.

Mike Ruby

They do exist on Spine line south of Mason City

DP Train makeup rules.

Rules require 5 cars of over 45 tons against a single DP unit, and 10 cars of over 45 tons against a 2 unit DP consist.  Exceptions abound, so what you see is what you get.  Sometimes DP is used as an ETD and is not worked in power.

At the moment, there is a ballast shuttle working the BNSF Stockton sub.  Two units are used on each end to allow a change in direction without running around.  The quarry is at Elsey, above Oroville on the former WP.  The train is cut into two tracks with all four units combined into one conventional consist.  This allows quarry personnel to move the cars for loading.

The 14,000 ton, DP grain trains coming from Canada, get cut into two empty trains going back.  This is to comply with 45 ton rule and to keep the trains small enough to clear in sidings.

Modeling DP?  Usual practice is to run DP linked to manual controls of the lead consist.  This would suggest that a model DP consist would run fine in DC, and would be part of the lead consist with DCC.  Leave a headlight on dim as a marker on the rear of the train.  UP DP will not link with BNSF DP, but all units will MU.  So, be sure that there is a unit of the same company as the lead unit, in each DP consist.

DPU in North Dakota

Just came back to Manitoba from Grand Forks ND today and saw an ~80 car sugar train (BNSF) heading south with one 6 axle Dash-8 on the head and two at the full rear. All of the units were under power judging by the smoke from each one.

- Bill