two shorter trains instead of one long one?

I admit I'm naive to how things work in the real world of freight rail, so be
gentle..

Suppose you have a LOOONG freight consisting of xxx cars, and require 6 locomotives
to move it where it is supposed to go, lets assume a long distance.

Would any thing be gained by breaking it down into 2 trainsets, each with
3 locomotives?

Will anything be gained in terms of starting and stopping difficulty? Is this
even an issue?

Would fuel efficency be equal between the two setups?

I'm guessing the disadvantages would include needing two crews, and the duplication
of routing of the two. But How about the reduced length of side track needed to allow
other trains passing?

OK fire away, educate me please!

We concur; until the Diesel brought about the use of multiple unit controls, freights usually topped out at around 75 cars, so "second sections" and extras were common. In the late Sixties, only Rio Grande held to a "short, fast, frequent ideology, and Reading experimented with siding-to-siding delivery, trains of less than ten cars with road crews doing the pickup and setout. This was called "Bee Line Service", and is referenced in the paint job on the NS "heritage" unit honoring the Reading, but it never worked out. Very long freights, however, probably peaked out in the early Seventies. Let's hear from some other members on this, please!

wborys wrote: needing two crews,

this
/thread

The problem with two shorter trains versus one longer train is four crew members versus two, and the two trains would occupy more track space than the single long train. The extra crew(and associated costs are obvious), the extra track space comes from the two empty signal blocks required to allow the following shorter train to stop safely. So if for example a single track section between sidings can handle 24 long trains per day, by cutting the long trains in half you would reduce capacity to the equivalent of 12 long trains.

On the other hand, if the line has a lot of restrictive curves, the longer a train is the longer it has to held to the speed for each curve, since the train cannot resume track speed until the last car is clear of the curve. If the curves are close enough together, the train may hardly ever be able to get up to the nominal track speed because the next restrictive curve is coming up just as the rear of the train clears the previous one. A shorter train might be able to speed up a little bit before having to reduce speed again. It's something that just has to be judged against the enhanced use of track capacity pointed out by JayBee above, based on the circumstances of each case.

Some times running 2 short trains is a lot more economical in places like the rocky mountains where there are steep grades to battle. Running a long train might be to heavy and to long and would require a mid train helper or a special car out fitted with an air pump to keep the air up in the train along with a pusher set and to help with stopping it.

In the winter months ice and snow can plug up air lines as well or cause air the line to bleed more than normal a longer train might take to long time to build up the air required to stop it. Running 2 shorter trains would take less time and have a better pick up time when getting ready to move and or stopping it.

DP is making longer trains more and more common. It is efficient to run fewer longer trains under many circumstances, as long as sidings and yards are long enough, and they don't get in the way of passenger trains. UP ran a 17,000 foot train with a 3-2-2-2 DP configuration a couple of years back just to show what they could do. In other countries, a lot of lines mix a lot more passenger and freight, so they tend to run far shorter trains that can accelerate and decelerate much more quickly. It also depends on the geometry of the line, although DP is quickly making that far less relevant. In the past couple of decades, sidings have also driven train length, and siding elongation projects have been undertaken in order to increase single-track line capacity with the same number of movements, although single track is inherently inefficient, and some re-double tracking and new double tracking have been undertaken recently.

Right now my employer is into really long trains. It seems to be a two edged sword. They can save crews, but parts of the route traverse urban areas. We also have many new dispatchers. I make the point that once we are under way, we need to keep moving. There are few areas where we can stop without having to cut crossings. Into the rural areas, the line is curvy. As was earlier stated, we must keep to the lower speed until the entire train is clear of the restriction. We haul many unit trains. Some use dp. The empties get filled out with general freight. This results in 8000' trains. The dp might exert too much force on the empty cars, so they run conventional. In a few months we will have freezing weather. 8000' might not ever be able to get enough air on the tail end. The brilliant managers get the idea for this large train to pick up a car. Now I have to pump air for ever. This is about the time that they ask what is taking so long. One time a boss asked this, and I told him he could help if he blew into the hose on the rear car.


Working in the east, I see long trains as a disadvantage. The terminals weren't designed for it, the sidings are too short. It is a nightmare. In unpopulated areas, it might be OK. I am waiting for the day we go into emergency in a city. It might take the conductor a half hour to get to the problem. Meanwhile an emergency vehicle is waiting, while some house is burning down on the other side. The method of long trains will change if the litigation of such an incident exceeds the cost of running two trains.

On my carrier, for the past 2 decades, 9000 feet has been the the normal maximum train length where siding length permits and even where siding length won't permit meeting opposing 9000 foot trains, 9000 feet will be authorized in one direction - opposing trains are limited to the siding length maximum (which on two routes I am familiar with it is 6200 feet on one route and 7500 feet on another).

Current practice when a train goes into emergency in a populated area - urban, suburban, small town etc - the local authorities get notified - so they can provide protection for their emergency services and potentially assist the Conductor in either fixing the problem or returning to the locomotive.

Long trains are a economic fact of life for US Class 1 carriers.