What is a Schematic?
September 6, 2012 by markpaulson
Remember to double-click on the photo to actually be able to see it! A “schematic” is a simplified version of the track plan, laid out with the main line running horizontally on the drawing. Note that this does not depend on the compass direction of the main line in reality. East, West, North, South….it all becomes left and right on a schematic. The way distances are represented also changes from a scale version of reality (the track plan) to a kind of “what comes next” arrangement. If there are no diverging tracks, industries, stations or points of interest, the length of a track, from one point to another, is truncated on a schematic. Compare the way distances are represented here with the revised track plan I just published.
The schematic for my Denver, Durango & Silverton took four photos to represent, end to end. For operators, if I ever get that far :-), portions of the schematic will be posted along the fascia in the areas to which they correspond. The purpose of this is to make the layout easier to understand, and to facilitate communication. I did a little color-coding, making the main line track red and the siding tracks blue.
I used my track planning program to create this schematic, so the track lines are not so rectilinear as they would be if I had drawn all of this free-hand. Also, the grid lines have no meaning. On the track plan they represent square feet, but not here. Eventually every item of note (tunnel, track, bridge, etc.) on a railroad needs to have a name, so that engineers can communicate their location to the dispatcher, and the dispatcher can instruct engineers on how far to proceed along the line, where to meet opposing trains, etc. For the time being, I have just started identifying some things by their location in the layout room, like “North Wall Tunnel”, shown here. Speaking of meets, on a railroad with a single track main line, like this one, sidings (blue) must be provided where trains going in opposite directions can get past each other. The length of sidings dictates how long the trains can be. Take a look at the Densel Washington film, “Unstoppable”, to see what happens when the siding is too short! My freight cars will all be seven inches long, and my passenger cars will be nine inches long. Lengths of locomotives, tenders and cabooses may vary, but must also be taken into account. I have indicated by each siding what the capacity is, with or without locomotive and caboose.
Durango is the most complicated trackage I have, but the schematic makes it much easier to understand. I also started to number the turnouts in this area, because they will have controls mounted in the fascia.
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