Z-Bend Track Module Ideas

Andy Hunting
Northwest Pacific Z Scalers
December 2002

This document is nothing more than a bit of brainstorming about how to make the most of the Z-Bend Track specifications for Z-scale model railroad modules. Any resemblance to ideas already discussed or tried by others, successfully or otherwise, is purely coincidental. Actually, I understand that Robert Albritton's modules embody some of these ideas, though with different dimensions and not to a particular modular standard. Anyway, I'd love to hear about any adventures or misadventures fellow Z-scalers have had with these or similar ideas.

Bent Z-Bend

Model railroad module standards in most scales discourage modelers from building mainline trackwork in anything other than a straight line, following the edge of each module. Curves on such modules are generally 90 degrees only, with the occasional S-curve made from two adjacent 90-degree elbows.

Z scale is small enough to permit modelers to curve the mainline away from the edge of a module, and still have room to return back to the necessary geometry at the other end of the module. However, even in Z scale, modelers must use fairly small curve radii to build much of a curve on a straight module of 4 feet or so in length.

With the Z-Bend Track standard, modules can be virtually any shape and still fit together into a workable layout. So if a modeler wants to build a curve, why not bend the whole module to fit it? I don't just mean regular-looking 90-degree bends as used in elbow and T modules, but any angle at all, especially more gradual and natural-looking angles. This way, the mainline can curve in one direction without having to dog-leg back again at the other end of the module. Sweeping curves with broad radii should be possible, even on a medium-sized module. There should still be room for secondary "scenery" tracks, as well as mainline features like turnouts or stations. There may even be more room available on such a module than on a straight module with a set of there-and-back-again curves.

A module bent at just a slight angle (say, 5 to 15 degrees) could make a big difference in the overall look of the mainline on a modular layout, adding to the variety and fun of modular railroading -- and further demonstrating the flexibility of Z scale. Even a 3-degree bend in a 4-foot module could result in more lifelike trackwork, and help break up the Great Plains straightaways so common on modular layouts without having to resort to cramped zigzags of track.

Some big questions are:

How easy would such a module be to build? If they're difficult or expensive to build, modelers will be discouraged from trying them.
How easy would such a module be to transport?
How much more floor space would a modular layout take up, when compared with a layout featuring straight and 90-degree modules?

To try to answer some of these questions, I've experimented with a few simple module layout drawings to see what they might look like. On these modules, I've used 15 inches as the minimum curve radius. The double-tracked Z-Bend curves are thus 15 and 16 inches.

Each curve is given an easement by offsetting the curve from the tangent track by a certain amount, and replacing a certain length of the tangent track and a certain portion of the curve with an easement "spiral" to transition from the straight track to the constant curve and then back again. For the longer curves, I've offset the curve by 0.5 inches and turned 5 inches of the straight track (plus a bit of the curve) into a spiral. On smaller curves, the offset is 0.25 inches, with 3 inches (plus part of the curve) as a spiral.

The background grid is drawn in one-foot squares. The dotted lines are the edges of the 5-inch interface zone required by the Z-Bend Track standard, in which only straight track is permitted.

Here are three sample modules, of 15, 30, and 45 degrees:

The dimensions shown are the smallest possible using the easements and curve radii I've chosen. The overall size of each module could be reduced further by:

using a smaller minimum radius;
using tighter, less gradual easements (or none at all, though I personally wouldn't recommend this);
increasing the radii of the curves on the outside elbow of each module;
beveling the pointed benchwork at the elbow of each module.

These modules are all reasonably sized compared to a 2-by-4-foot straight module, and would fit into a similar space for transportation. Each module could be built longer without increasing its width. To increase the length of a module without changing its width, the mainline curve radii must be broadened to fit. Of course, there's no reason why the module edges need to follow the right-of-way, if a builder wants to add more room here or there.

How easy and affordable would these be to build? Clearly, the 1x3 or 1x4 sides of the modules would need to be mitered to fit together snugly, though the benchwork could be squared-off in places so that most of the angles are 90-degree. More individual pieces of wood need to be cut and fit together than on a rectangular module. On sharper-angled modules, two of the four legs might have to be placed closer to the elbow to keep the module from tipping. These modules do not use sheets of plywood or foam as efficiently as rectangular or square modules might (if their dimensions are multiples of 2 feet). This could result in more waste of material, depending on the design. All these factors could discourage some modelers from trying such modules.

Hopefully, the scenic possibilities would outweigh the drawbacks. The mainline tracks along the outside of the elbows have been given 15" and 16" radii on the sample modules, and this provides some straightaway sections where turnouts could be placed to connect secondary tracks. The outside curves could be given even broader radii if a modeler chooses. The 15-degree and 30-degree example modules could be built longer, allowing ample room for secondary trackage while still remaining virtually the same size as a 2x4-foot rectangle. A four-foot bent module with a bend of 5 or 10 degrees should be able to hold almost anything that a 2x4-foot rectangle can hold.

Are Broad Curves Possible?

T-shaped and X-shaped modules are a particularly attractive feature of the Z-Bend Track standard to me. The small size of Z scale makes this sort of flexibility possible. But what happens if the minimum curve radius is expanded beyond 9 or 10 inches? I made a couple other experimental drawings to see what dimensions similar modules would have with a minimum radius of 15 inches.

First, here is a "balloon" end module similar to one of our club's modules.

Our club's module is slightly longer (about 50 inches), due to some generous easements. But a 3-by-4-foot module is possible.

Just by doing the math, it's clear that an X-shaped four-way intersection module with 15-inch minimum radii would be close to 6 feet square, without easements. A T-shaped module would need to be about 6 feet by 4 feet. Those 90-degree curves can take up a lot of space. How about a Y-shaped module?

It's a fat one compared to many Z modules, but at about 4 by 4.5 feet it may still be reasonably transportable. Shorter easements could shave 2 - 3 inches off the short dimension, and perhaps 4 inches off the long dimension.

The Big Picture

Finally, here are a few layouts using these example modules to see how much space they might take up, and how they might affect the overall look of a layout. The background grid is one-foot squares again.

Straight modules only, with 15-inch-radius balloon ends:

Replace one of the 2x4-footers with a couple bent modules:

Even with bends of 15 degrees or less, a layout can be given extra visual interest -- in almost the same amount of space.

Add a Y module and lots of caffeine, and...

It definitely bears little resemblance to the modular setups at most train shows -- a testament to the strange power of Z! :-) Note that this monstrosity fits in a space only 15 by 25 feet, with room to spare. With some careful planning, perhaps using cut-out graph-paper shapes, a number of module combinations could be arranged to fit in a given space.

All input and observations are welcome!

-- Andy Hunting zscale@retrograde.net