Model Train Trackwork Basics
This is not the definitive article on trackwork. It is, however, a reliable guide on ready-to-use products that can make your first layouts easier to build, easier to rebuild, and more fun to run. The suggestions that I am going to make come from the experience accumulated over the years of operating a model railroad-oriented hobby shop and, of course, from my own modeling.
It has been said many times that good trackwork is the most important part of successful model railroad operation. This is the truth. The temptation to lay track down quickly to get the trains running is great, and I've succumbed to it myself, so you probably will have already tried your hand at tracklaying by the time you read this. Some of what I will say will already be beginning to make sense to you. As the majority of active modelers are in HO, that is the product area that I will concentrate on, although most of what I will cover will apply to N scale and other gauges as well.
Track is generally made of one of four materials: brass (the gold-colored metal), zinc-coated steel (dull whitish gray colored), steel and nickel silver (the color of a five-cent piece). The first two types have been most common in train sets, but I would suggest the nickel silver. Brass conducts electricity well, but it needs the most care and cleaning. The oxide that it forms is a poor conductor. This means going over the rails with a track cleaning block or car frequently. With the zinc-coated steel, the zinc coating wears away and leaves the steel exposed and steel will rust. The nickel silver is not quite as good a conductor, but its oxide is about as good a conductor as the original This will provide reliable operation.
Sectional track: Not only are the materials for making track not equal, but track comes in different lengths and shapes as well. New modelers generally use the 9 inch long pieces of sectional track that come in sets. Atlas, one manufacturer, calls their line "Snap Track." Others make similar track, too; some mounted on plastic roadbed. It is made in straight and curved sections with radii of 15", 18" and 22". In addition, "Snap Track" pieces may be bought in 1/3, 1/2 and 2/3 lengths, as well as in small straight and curved fitting pieces.
There are a few simple but important rules to remember when you lay track. The tighter the curve, the smaller the cars and locos you can run. A 15" curve will limit the size of the equipment that can run without jumping the track. For example, an old-time 4-4-0 and 34-foot freight cars may work well on such tight curves, but a modern SD4O-2 six- axle diesel hauling a bunch of piggyback flats will be off the track more than on. It takes about 40" to lay out a circle of 18" radius track, and 48" for a 22" radius. The 22" is better to get around, but if you use a 4x8' sheet of plywood as a basis for your railroad, you will find that 22" does not fit well. You will end up using 18" much of the time as many modelers do through both choice and necessity.
- Click for larger graphic - Let's lay out an oval of sectional track on a 4x8' board just to get the feel of things. The radius is measured from the center of the track to the center of the curve. A circle of 18" radius is 36" across, which is why about 40" is needed. An oval made of twelve 9" straights and a circle of 18" radius will fill out most of the plywood, but won't come to the edges. There is room for another line of track, if you wish, with 22" radius. One less straight piece would be used on each side of the inner oval.
Sectional track uses a slotted clip called a rail joiner to connect the pieces. This piece provides both electrical and physical connections. The fit must be firm and not sloppy Now, it becomes obvious why the track should be fastened down. The movement of the trains will work it loose, derailing the train or breaking the electrical circuit. The holes in the middle of the ties may be used to tack the track in place. This is one way that HO differs from the 0-27 trains many of us grew up with.
- Click for larger graphic - The rail joiners slip over the end of the rail, but they can be misaligned to the point that one rail is on top of the joiner, causing a bump which would be very large on a real railroad. That kind of bump can derail a train, scale or real, so fit the sections together carefully.
There should be no gaps at the ends of the rails on either the curves or straights. Gaps are something for the wheels to fall into, with the same result as humps.
- Click for larger graphic - When you deviate from the basic oval when using sectional or "Snap Track", you begin to see the need for the small fitting pieces. Adding turnouts (track switches) for sidings and crossovers may change the way the sections fit and cause gaps of an inch or more when you bring the oval together. Don't force the sections! Somewhere this will cause a bind or misalignment in the track. Use the short lengths to make a smooth fit.
Adding power and turnouts: To get electrical power to your track, most of the sets come with a terminal section. Atlas has a set of wires fastened to two rail joiners; these help hide the wires. You can solder wires to the outer faces of the rail, but you run the risk of melting the plastic ties and losing the correct gauge of the track (the distance between the rails).
Rerailer track sections are also made; some look like road crossings. I prefer the straight ones over those that are curved. There are also track crossings at various angles to allow tracks to cross one another or to make figure eights. The sectional track from different manufacturers is normally interchangeable.
A loop will let you run your trains, and a loop within a loop can let you run two trains if you have the power packs for them. However, it isn't until you add turnouts (switches) to connect them or for sidings for industries or yards that the fun of operation comes.
Turnouts come in different sizes and quality of construction. The most common sectional track type is a No. 4, which fits roughly in the space of a 9" straight section. The turnout that goes to the left is simply called a left or lefthand and the right, a right or righthand turnout. Both of these have a straight route through them. A wye turnout curves off to both the left and right, but does not have a straight ahead part. The turnout numbers describe the size, and the smaller the number, the sharper the turnout. On a No. 4 the diverging route moves away one inch for every four on the straight side; a No. 6 has a one in six ratio, which means it is not as sharp. It does take up more space, though, since it is longer. In sectional track. you could consider the No. 4 to be like an 18" radius curve and the No. 6 a 22".
While the least expensive turnouts will work fairly well right out the box, they use a thin metal stamping for the movable point rail. The point will occasionally need to be straightened with a needle nose pliers, and the pivot location sometimes needs to be tightened with a small center punch on the riveted types. The better turnouts have points made from the same rail as the stock rails (the outer fixed rails). They may have a notch cut in the stock rails so the points do not pick at passing wheels.
Another area of difference can be seen in the frog of the turnouts. This is where the rails cross each other. Some turnouts have metal frogs and some bring the rails up to each other, then insulate them with plastic. If a metal frog is insulated but not powered, you may have some locomotives that will stall on the switch. This is more likely in N than in HO. Even in HO, some locos don't pick up power on all their wheels, giving trouble on some No. 6 switches. Atlas has a product called a "Snap Relay" that will power their Custom Line Mark II and III turnouts if you experience this problem. Some turnouts come with a long switch machine mounted on one side, while others have removable machines, and there are also 'under the table' electrical switch machines. There are manual 'ground throw' switch machines, too. Caboose Industries makes one that looks much like the real ones, and it works well. Atlas, Bachmann, AHM, Life-Like, Model Power, Roco and Tyco turnouts are all electrically interchangeable and all use the same size of rail.
Now, after talking about all of this, there is another kind of turnout which matches the above types physically, but is electrically different. Those listed above have the siding electrically live with the same power as the mainline unless an electrical toggle switch is installed. The other kind of turnout is called a selective turnout. It selects the way the power is routed by which way it is thrown. When it is thrown for the siding, the siding is powered and the straight route goes dead. When it is set for the main, the siding is dead. This creates a different wiring situation, and you must be certain that the rails leading out of the turnout are properly insulated to prevent shorts. This is no problem at all, but it is different from the turnouts that you will usually use on your first layout.
Although I don't want to go too deeply into this matter, I will point out that rail comes in different sizes. Most HO sectional track products are code 100, which means that the rail itself is .100" high. Code 70 and 83 are also used in HO; they scale out closer to actual common rail sizes, and are .070" and .083" high, respectively Some of the manufacturers that make products with these sizes include Walthers/Shinohara, Rail Craft, BK and Railway Engineering. This is not a complete list, by any means.
