…design choices for T-Trak modules
You thought T-Trak was simple, didn't you? Then you took a closer look at the T-Trak data sheet, browsed the Web sites, and discovered that things were a little more complicated than you thought. Don't panic. Let's walk through the various options…
25mm or 33mm track spacing?
The T-Trak data sheet lists not one, but two standards, which differ mainly in spacing between the two tracks. The 25mm track spacing, given as suitable for "trolleys, small steam, and up to 4-axle engines," simply butts both straight tracks against each other. This yields a center-to-center track spacing of about 25mm. By NMRA standards, that's a little tight, and it requires some clever manipulation of track pieces on corner modules to make it work.
The more common spacing places the two tracks at 33mm, which happens to be the spacing designed into the Unitrack product line, from curve radii to double-track pieces to turnouts. Even the rerailer is designed for it. The 33mm track spacing is adequate to ensure that trains won't sideswipe each other on curves.
The 25mm spacing remains as a legacy of T-Trak's modest beginnings, but is functionally obsolete in a world where many hobbyists are using T-Trak modules for modern American railroading. Most modules in use today are built to the 33mm standard, which is just as easy to build (easier, if you're building something other than a straight module), and much more versatile.
Bottom line? Build to 33mm track spacing, unless you have a very specific reason to do otherwise.
The length of a standard T-Trak single module is 12-1/8", which seems odd, right? There is a logic at work here: straight sections of Unitrack are manufactured in increments of 62mm. Multiply 62 times five, subtract about 1/16" to permit the track to overhang the module a little, convert to English measurement, and there you have it.
A double module is just that—24-1/4" long, good enough for an extra structure, a crossover, or a short siding.
Longer modules, such as triples or quads, are useful in situations where you'd rather not break up a complex track arrangement over multiple modules. (For example, I'm in the process of building a Timesaver into a quad module.) As length grows, however, the module becomes more cumbersome to transport and store, and you're in danger of drifting away from the T-Trak philosophy. If you find yourself planning many large modules in pursuit of your hobby goals, maybe you're better served by a different modular standard.
Bear in mind that module lengths are by no means limited to multiples of 12-1/8". Non-standard lengths can be useful in certain situations.
Standard depth of a T-Trak straight module is 8-1/4". I find that to be plenty of room for a slim yet evocative slice of scenery, complete with lineside structures and a siding or two. A more complex scene, such as an industrial district or yard, may call for greater depth, but this is easily accommodated with T-Trak.
Some clubs encourage straight modules built to a depth of 14-3/8", which matches the depth of the "alternate" corner design. With this size, back-to-back modules meet each other, thereby avoiding the "hole-in-the-donut" look that assembled T-Trak layouts often have. If contiguous scenery is important to you, this is a worthy consideration. (For myself, that extra depth means more layout to transport and store, but not necessarily more railroad to run.) The choice is yours. Check around to see what the T-Trakkers in your neighborhood are doing.
What size corners?
The published "alternate" corner design, 14-3/8" (365mm)wide, has curves of 11" (282mm) and 12-3/8" (315mm), good enough for most N scale rolling stock. It's popular, too; most of the corner modules out there are built this way. The major choice seems to be whether to build your corners as published, or glom a pair of them together into a 180-degree curve. People have done both. The wide range of curves available in the Unitrack line suggest that you could tailor your corner module size to fit your space or equipment with little difficulty. I haven't yet seen a wide-radius corner module built with those lovely superelevated double-track pieces, but I'm sure somebody is working on it.
Skyboard or no?
The nifty curved-edge skyboard on Lee Monaco-Fitzgerald's original module has caught many a modeller's eye. Should you include skyboards on your modules? Many do. I'm going to make two arguments here against skyboards: one artistic, one pragmatic.
From a typical viewing angle, a T-Trak skyboard should not show sky! Rather than launching into a long-winded discussion of art theory or two-point perspective, let me just point out this: when you look out upon the landscape, the horizon line (bottom edge of the sky) always appears at your own eye level. This holds true whether you're standing on the beach, or on the observation deck of a skyscraper. Now consider a T-Trak module, sitting on a folding table. Ground level is about 32 inches above the floor. The top edge of the skyboard would be a few inches above that. Unless you're under the age of seven, your eyes are higher still, looking down upon your trains. Directly behind the trains would not be sky, but more land. Under such viewing conditions, a convincing illusion of unending countryside will be difficult to obtain.
Skyboards block the view across the layout. I don't know about your club membership, but Type 2 Diabetes and knee replacements run rampant in ours. Rather than hovering about during a show, we grab folding chairs, retreat to the operating pit, and tend the layout from there. The presence of skyboards impedes our view of the layout's far side, and any potential problems — stalled locomotives, open turnouts, errant young fingers — that may arise. This cuts both ways: children and the wheelchair-bound on the spectator side of the table aren't able to see the back row of modules, either. Granted, there may be circumstances where view blockage is desirable — say, for a staging yard — but in general, it's good to let everyone see all the modules.
Once you've made your decisions, it's time to start building. Have fun!