HI Folks: I am working on modeling a section of railroad that has a LOT of grain traffic in it, but will also have some oil and coal. the thing is most of the traffic isnt enough to fill a unit train at the grain loader, Mine or Pipeline terminal. I watched this video today of loading a grain shuttle -- it appeared to have 20 - 30 cars, and really REALLY fits what I am trying to model. What I need to know is what the procedures are for building up a unit train from this, and what the operating schedule would look like? Multiple shuttles? one shuttle going out and picking up cars from all the elevators along a section of track? how does that work. Then, do they bring them all back to the yard to build up the unit train? Im purposely not putting this in the BNSF folder, even though my railroad is BNSF, b/c I want to hear what lots of different systems do, so I can synthasize what is gonna work best in my situation Thanks TIM
As a rule, a unit train of ANYTHING remains as a unit train forever........unit trains are not made, they exist. In the case of grain, smaller quantities would most likely be sent to a larger elevator that has the volume to load a unit train......or the smaller quantity would be sent to a customer who needed the smaller quantity.
An example of a current operation could be the Washington Eastern Railroad. It is an out and back operation. On their way out to the end of their line, they drop off empty grain hoppers. The next day when returning "home", they pick up the loads and set them out at the interchange with BNSF.
In a situation like that, it's sort of what Dave said, it's not a unit train at the load out. Depending on delivery window and destination, it could remain in the small block of cars all the way to a customer or it would be moved to a yard where the blocks of cars from the small elevators all going to the same destination in the same delivery window would be combined into one train that's not truly a unit train but would appear as one in transit and at the destination point.
What a unit train is, is a group of cars traveling on a "unit train" freight rate on the same waybill. One waybill, many cars. How big the unit is depends on the rate structure the railroad offers. For coal and grain trains it could be 100-150 cars. For rock and sand it could be 25 cars. Railroads might have hundreds of unit train rate for different commodities and different routes. Unit trains may be made of smaller units, so a 75 car unit train could be made up of 3 25 car units. However the vast majority of unit train rates are for larger blocks, 75 to 150 cars. Unit trains stay together for duration of the trip, unless the cars are bad ordered. Once empty, the cars may be changed around. In my experience a consist of cars only made a max of 3 or 4 round trips before some of the cars changed. Grain trains, ethanol and rock trains are particularly subject to change. Coal trains and specialty units are more likely to stay together. Trains made of cars that are loaded and unloaded together as a train are more likely to stay together, trains made of cars that are split into groups to spot for loading and unloading are less likely to stay together. Modern coal loading is done with flood loaders and emptied with in train rotary dump or automatic bottom dump doors so the train isn't broke to load or unload. The only time coal train cars get swapped out is when cars are bad ordered. The BO car is set out and a replacement car is added. At N Platte NE, at the UP Bailey yard on the NW corner is an entire yard dedicated to handling empty spare coal cars. It even has a balloon loop to turn the rotary ends properly on the cars. After a while a unit train will be "purified" and added rail cars will be replaced with the proper cars for the service. If a 100 car Ameren train has had 15 Amaren owned/leased cars go bad order and replaced with 15 railroad owned/leased cars over the last dozen trips, when they get 15 Ameren cars in the spare yard, they will switch out the RR owned cars and replace them with the Ameren cars. Grain trains can be even more fluid since they use a lot more railroad owned/leased/pool cars. If grain is running heavy a railroad might put a dozen grain trains into an elevator in a week. The empties will come out as they are unloaded. The first 100 empties go on the first train, the 2nd 100 empties on the second train. Since most are railroad owned/leased cars, it doesn't matter. It was also common to route empty grain trains to a central location where the cars would be inspected and the grain sets filled out and purified. Once again trying to get Peavy cars in a Peavy train or taking a 95 car unit train and filling it back out to 100 cars. That changed a bit in the 1980's when railroads went to "shuttle" trains. A shuttle train on the UP was a grain train that had to be loaded in 24 hours, and had to be unloaded in 24 hrs. In exchange, the railroad offered a lower rate and agreed to keep the power with the train so the load could move as soon as it was loaded and the empty could move as soon as it was empty. Those trains tended to stay together more than a regular grain train. Since aggregates, ores and ethanol tend are often loaded as cuts of cars, rather than as a solid single train, they are less likely to stay together on subsequent trains. Also unit trains may tend to cycle between "families" of origins and destinations. Arkansas Power & Light might have three power plants and buy coal from 2 different mines, so the unit trains will tend to stay in that service, but a train loaded at mine 1 might go to any of the three power plants, and when empty could go to either of the two mines. Railroad owned sets of coal cars are even more variable, since the railroad can shift them to different mines thus different utilities as the business demands. They might also change cars as required. If a utility wants to load a 125 car train, but all of it's leased sets are out running, the railroad might have a 100 car set on standby, and fill it out with 25 cars, and then send it to the mine to protect the loadings. When it comes back empty it might reduce down to 100 cars to load for a mine that handles 100 car trains.
Excellent explanation - a Unit Train can be virtually anything the Carrier and Customer agree to place a Unit Train rate and loading/unloading requirements upon. I have seen Unit Train rates and conditions applied to as few as 20 cars. The loading/unloading requirements are to enhance the car turn times - maximizing revenue on equipment investment.
