Modeling Short Train Lengths

       As we strive to make our layouts larger and more realistic in representation of the prototypes we see, remember or imagine - a number of techniques and schemes are utilized.

       Selective compression provides for inclusion of an industry, scene or geological feature that is way too large to model in its entirety. Fast time clocks allow for the faster passage of time, more realistic operations and the sense of greater distances between towns or industries.

       Smiles were introduced in the late 50's as a means of providing scale speeds and distances to our layouts. The use of switch lists, way bills, and other control forms provide prototypical operations and a sense of purpose to our trains.

       Adherence to a specific prototype, its details and surroundings impart a feeling of "correctness" and sets the stage for both the trains and their operational behavior. So too, we look to impart more prototypical modeling in the use of lighter rail size, thinner wheel contours, larger frogs and radius curves and functionally scale couplers in our quest for realism and operation.

       In the operational area the use of speed restrictions, momentum starts and stops, situation cards, and realistic time intervals spent at locations for water, brakemen walking back to the end of the train, or waiting for the build up of air pressure prior to departure are examples of stretching the layout and capturing more enjoyment.

       Helpers are employed in simulated and real grade situations. Multi-unit consists are used to haul unit trains and fast freight loads. Conversely, a small switcher handles a few car task on the local. In fact, only a single car behind a Doodlebug is common even though the engine could (in our model version) easily haul 10 cars or more.

        I would like to add an additional element; the use of scale/speed restrictions based on prototype realism. The table is from the pages of "The Engineers Handbook" by AlcoGE (circa late 1940's) and represents an Alco GE 1000hp Switcher rated at 115 tons. The original table used speed and grade as the basis to determine the total trailing tons the locomotive could haul. This would perhaps be determined by the conductor adding the combined tare weight (LTWT on car sides) from each individual car plus the waybills load weights (don't forget the Caboose!).

        As each train is made up and blocked in a yard the appropriate motive power is matched by the tonnage and grade requirements of the terrain; real or modeled. I added 2 charts to make this job easier: a conversion to 40 ton cars (as originally stipulated in the handbook) and a 100 ton chart for ease of use. Just count the number of cars in your train and determine, based on your layouts grades and track speed requirements, if the motive power selected is capable of handling the cars required.

        Let's suppose for example that your layout has moderate grades of 1.5% and one mining section with a grade of 3.0% grade. When flat switching in the yard at under 10 miles per hour any size cut of cars we possibly model (over 55 cars of 100 tons each) is within the realm of the prototype's ability to move them.

        But, what happens as we get out on the mainline? As speed increases and the grade increases there is a sharp decline in car hauling capacity. Our moderate grade of 1.5% allows for only three 100 ton cars or up to seven 40 ton cars at 15 miles an hour.

        Allowing for partially loaded and totally empty cars, it appears that the "short" train lengths we model of 10-15 cars is just about right. The introduction of model grades above 2% decreases the number of cars drastically so that very short trains (3-5 cars) or the use of helpers are required.

        Now, not only can we add a prototype task to the yard list, but we can be aware of the road switchers hauling capacities under varying conditions and have a great reason to justify our very "short" trains…

Steve Lynch 1999