The Basic Stats

Let's look at the basic "layout description" statistics and how to compute them. We list each stat name (with its units), define it briefly, tell how it is calculated, and then discuss what that stat tells us about the design.

ROOM AREA (sq ft): Calculate the layout room's square footage. If your room is much larger than the layout -- such as a 4x8 layout in a large family room -- then only include a reasonable amount of access space around the layout -- don't include all that extra room space. For instance, with a 4x8 layout in a large recreation room, you might add a 2 foot aisle all around the layout. This means the total "room area" for a 4 x 8 layout might be 8 x 12, or 96 square feet.

This stat tells us the approximate space requirement for a given layout, regardless of its shape. This is a clue that two differently shaped layouts could be altered to fit into each other's space. This won't always work, but at least it's worth exploring.

LAYOUT AREA (sq ft): Calculate the total area taken up by just the layout "tabletop" itself. This does not include aisle space. For the 4x8 layout, this will be 32 square feet.

This stat allows us to see just how much layout we really have, and is a valuable design statistic since it allows us to directly derive the amount of benchwork and scenery the layout needs. By comparing the room area with the layout area, we can ascertain how well the layout design fills its space. For instance, the 4x8 layout's space usage is 32/96, or 33%. Most along-the-wall designs have an space usage of 50% or more, which shows us the 4x8 layout doesn't fill the space nearly as well as an along-the-wall design.

Filling the space isn't the only issue, since we could build a wall-to-wall table and fill the space 100%. Access, however, would be abysmal. As long as good access is maintained, this stat is useful --but it must be viewed in context with your other design needs and goals.

NUMBER OF TURNOUTS: To compute this stat, just count the number of turnouts on the track plan. Also count a crossing as a turnout, and count a single slip switch or three-way turnout as TWO turnouts. Count a double slip switch as THREE turnouts.

This stat is a good indicator of trackwork complexity, which tells us many useful insights. Given that the most costly trackwork is a turnout, the most maintenance intensive trackwork is a turnout, and the most interesting trackwork operationally is a turnout -- depending on what trade-offs we're after (less cost, less maintenance, more interesting operation), more or fewer turnouts may be preferable. Combining this stat with the next one on total trackage gives us enough information to do a rough estimate of the trackwork and wiring costs for the layout.

TOTAL TRACK (ft/cars): Determine how many feet of track are on the track plan by measuring it. Record the result as both total footage and as the equivalent number of 40 foot cars. Using 40-foot cars in the stats allows us to directly compare track plans across scales. To determine the 40 foot cars equivalent for a track plan, use the appropriate factor from the following table:

Scale	Cars/ft
O	1.0
S	1.5
HO	2.0
N	4.0
Z	5.0

For instance, if an S scale layout has a total track of 211 feet, then the cars equivalent will be 316 cars (211 x 1.5). Drop any fractions -- don't round. It's best to deal only with whole car lengths and lean to the conservative side when computing car capacities.

This stat, in combination with the other track stats below, tells us much about the operational possibilities of the track plan.

MAINLINE TRACK (cars): Measure the length of the mainline in feet and convert it to the cars equivalent. The main route of a branchline is also considered mainline for the purposes of computing this statistic. Also, one track running through any visible yard and any staging yard needs to be designated as part of the "main" and included in this total.

As an exception, the offstage portion of a single track that runs into staging to be used as car storage/interchange is not "mainline" but instead is "staging" (see below).

From this stat, we get a sense of how much "mainline" running is available on the layout.

PASSING TRACK (cars): Measure the length of each passing siding in feet and add them together. Do not count track where the main would be fouled if cars were on the siding. That short chunk of track from the turnout points to the clearance point is connecting track (see below), not passing track. Convert this figure to the cars equivalent.

This stat helps us determine mainline traffic levels (more on this later).

STORAGE TRACK (cars): Storage track is the amount of track in industrial spurs and yard storage (but don't include staging, that's a separate category below). Measure and total up the length of track in this category, and convert it to the cars equivalent. Like passing track, don't count track in this total where the connecting track would be fouled. Remember one track running through any yard was counted in the mainline total and is not to be included in this total.

STAGING TRACK (cars): Measure the total amount of track used to stage trains and compute the cars equivalent. Again, don't count track where the connecting track would be fouled. Don't forget that one track running through any staging area was counted in the mainline total and is not to be included in this total.

Remember the one exception -- the offstage portion of a single-track car storage/interchange track is "staging", not "mainline".

SERVICE TRACK (cars): Service track is loco storage, servicing, turntable, turntable leads, and so on. The rule of thumb is: if the track is used to store cars, then it is storage (or staging if it is "offstage"), if it is used to store locos and is traversed primarily by only locos, then it is loco service track. Measure the total amount of track used to service locos and compute the cars equivalent.

CONNECTING TRACK (cars): Connecting track is what's left. Compute it as:

Connecting track = total track - mainline - passing - storage - staging - service

Connecting track is what allows us to make up and break down trains, and to maneuver cars from the main to industrial spurs and yard tracks. It turns out this track is ESSENTIAL to getting a layout that can move a LOT of cars.

PASSING SIDINGS: Record the number of passing sidings.

PASSING TRAIN LENGTH (Cars): Write this stat as three values separated by slashes -- longest/average/shortest. Longest is the length of your longest passing siding in cars. Average is the length of an average passing siding in cars, computed as: passing track / number of passing sidings. Shortest is the length of your shortest passing siding in cars.

STAGING TRACKS: Record the number of staging tracks.

STAGING TRAIN LENGTH (Cars): Write this stat as three values separated by slashes -- longest/average/shortest. Longest is the length of your longest staging track in cars. Average is the length an average staging track in cars, computed as: staging track / number of staging tracks. Shortest is the length of your shortest staging track in cars.

Ideally, staging train lengths should more or less equal the corresponding passing train lengths. Significantly smaller staging train lengths mean extra switching will be involved in getting a "full length" train into or out of staging. Larger staging train lengths mean full length opposing trains from staging will clog the main. The longer of passing or staging train length should rule in determining typical long train length. The shorter of passing or staging train lengths should rule in determining typical average and short train lengths.

You may notice that staging tracks and passing tracks appear somewhat interchangeable in these formulas. This either/or use of staging and passing sidings reflects an operating session reality (one that was actually exploited by Tony Koester on his AM, by the way) where the layout's staging can be viewed as "virtual passing sidings". For example, the dispatcher could set up a "meet" between opposing trains to occur offstage. To do such a "meet", one train exits the layout into staging, after which a different train enters the layout -- as if a meet had just taken place in an offstage passing siding. If some of the passing sidings on the layout are rather short, this can be a useful technique for arranging meets between longer trains.

article index
page 1 : Find out if your layout will work before you build it
page 2 - current : The basic stats
page 3 : Operation potential stats
page 4 : Some examples
page 5 : Summary form
page 6 : Estimating building time and cost
page 7 : Some additional insights
page 8 : Comments and rating

The Basic Stats

Search Joe Fugate's Siskiyou Line

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September 2010

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