Two Key Questions for Track Plan Compression – Derby, VA Case Study

One of the toughest parts of prototype modeling is knowing where and what to compress to keep as true to the prototype as possible for a given space. In an ideal world, we wouldn’t have to compress any scenes, but that’s a fairy tale for all but the most compact of prototypes. We’re stuck with the challenge of trying to find the right balance of scenery elements and operations to model our prototype within our space constraints.

The coal mining town of Derby, VA on the Interstate Railroad offers a good case study of how to compress a prototype operation to fit into a range of spaces with different trade-offs, and it’s covered in good detail in Ed and Hugh Wolfe’s great book Appalachian Coal Hauler. The modest-sized tipple at Derby operated until the 1960s but is representative of operations built in the 1920s. Located at the end of a branch, it had a two-track tipple fed by a small mine railroad with an empty yard above the tipple that could be used to feed hoppers into any available loading track. On the load end of the operation, a single long siding was used to hold loads from both tipple tracks with a runaway spur at the end to protect from cars running away down the 3+% grade. A row of company houses lined the narrow valley in front of the tipple. Because the branch was so steep, the Interstate shoved empties up the branch from the yard at Andover, VA, and a cab, 10-12 cars, and a single locomotive was a typical train. Upon arriving at the tipple, the crew would drop their cab in the first tipple track, shove the empties past the tipple into the empty yard, retrieve loads from the load siding (and perhaps the second tipple track), back into the cab, and head back to Andover with the loaded train.

Track arrangement A shows what this operation would look like in HO scale if we modeled it to near scale. It includes all tracks (a tad shorter than the prototype), a near scale model of the tipple (compressed a bit from front-to-back in the scene), and six company houses to round out the scene. It also includes a portion of the mining railroad that fed the tipple. It holds about 9-10 empties and 9-10 loads (~80% of prototype), and because it’s based 100% of the prototype, it would allow 100% prototypical moves for model operators. That’s great, but the scene takes up a whopping 14 linear feet of real-estate, a premium most of us aren’t able to dedicate to a small operation on a layout. Some compression is in order. . .

The two questions I’d ask before compressing a scene are 1) what are the key elements that represent this scene, and 2) what tracks are key to reasonably prototypical operations. For the first question, the key elements at Derby are the tipple modeled near scale and a representation of the company houses that lined the tracks. You’ll notice in all three drawings the model tipple is the same size–some tipples are “compressible” without losing the feel (5 tracks to 3-4, shorter conveyors, etc.), in my opinion Derby is not. Answering the second question is a bit more complicated. The absolute minimum tracks required are the two that go under the loading portion of the tipple, but the third track of the branch beside the tipple is also important for the scene and to allow space for swapping empties and loads. The run-away track isn’t essential, but it does have scenic value and it helps communicate the steep grade to viewers. The single load track arrangement adds to the long feel of the scene and makes operations more prototypical, but it’s not “essential,” per se.

Track arrangement B shows what can be achieved in about 70% of the original space. The two small yard ladders behind the tipple are the biggest culprit in making this scene super long in arrangement A, so I’ve eliminated them here and instead merely extended the tail tracks of the tipple to hold the empties. Scenically, the tipple is the same, it still has the long feel of the prototype, it can still hold more than 9-10 empties and 9-10 loads, and you still get a bit of the town and mining railroad, but you save a lot of length behind the tipple. Operationally, the crew’s moves are just a little more complicated than the prototype–instead of shoving past the tipple to the empty yard, the crew would need to shove empties directly under the tipple, using the branch main to hold any loads that need to be moved out of the way first. A pretty reasonable compromise that cuts our scene from 14 to 10 linear feet.

But what if 10 feet is still too much? Now we’ve got to make some tougher choices. The biggest culprit here is the single load track, so if we eliminate it and just use the tracks directly under the tipple, we can save a lot of real-estate. Scenically, the tipple is the same, though it’s now pushed up against the end of the scene, and there’s less room for the town. Still, our tipple can hold about 8 empties and 8 loads, and operations aren’t all that different with the crew backing the train in and using the branch main to help remove the loads before spotting the empties directly under the tipple. In this case, our whole scene only takes up 6 linear feet, and if we eliminate the run-away track, it’s down to about 4.5 feet. That’s about 30% of the space of the prototypical arrangement in plan A while still preserving about 70% of the scene and 80% of the operations.

By applying this type of compression to an entire layout, you could accommodate considerably more scenes and operation for a given space. Of course, every compression is a compromise, and every prototype modeler needs to decide how much is good enough to meet their desires for their layout.