The signal systems used on the real railroads have grown so elaborate and complicated that it is really impossible for the average miniature railroader to keep up with them. Some of the big metropolitan model-railroad clubs, and a few exhibition layouts built by the railroads themselves do actually reproduce these complex features, but the individual who operates his own layout in basement or attic is better content with something more simple.
To a modelmaker, signals can fulfill any of several basic functions. First of all, they can look real; that is, they can be inserted solely for the purpose of making the right-of-way look like a big railroad’s. That puts them in a class with station buildings, telegraph poles, and whistle posts. To fulfill this function, the signal only has to have the outward appearance of its prototype, and construction can be correspondingly simple. Just a wooden dowel for the mast, a cardboard semaphore arm, bits of wire, wood, and other miscellaneous parts, when painted, can make a very effective looking replica.
The next step is to make the signal look as if it is working the way a real one should. If you have ever watched a signal when a train approaches, you will see that the indication remains at “clear” until the locomotive reaches the signal, then changes to “danger,” and stays in that position for an interval. When the train has passed on into the distance, and the block is clear, the signal goes back to green.
On a model layout. this is the simplest type of automatic signal you can use. Semaphores working like it are made by Lionel, and color-light signals formerly were manufactured. The type we are discussing shows “clear” when the train approaches, and has a normal “danger” setting. It is just a matter of changing the construction to suit.
A third development in model signals is to make the signal show whether or not a previous block is occupied, to indicate whether or not it is safe to enter. Such a setup is similar, of course, to the function of a real signal, which is placed as a warning to the engineer. On a model railroad it finds its chief application where an attempt is made to reproduce the actual operation staff of a real railroad, with one enthusiast acting as “engineer,” another as towerman, and so on.
It should be noted that such a signal does not actually stop the train, either in real life, or on a model, but in both it can be made to do so by the addition of “train control.” On real railroads, train control comes into operation only if the engineer fails to obey the signal, but on a model layout it comes into play each time if a locomotive approaches a danger signal. The Lionel Corporation makes a train control that stops the train on a red light, then keeps it standing for an interval. The light turns green, the train proceeds, and as the last car leaves the block, it turns yellow.
There is still another class of signal having wide application to models – the remote-control signal. A switch, at the “signal tower” or any other convenient point, controls the indication of the switch, making it go to “clear” or “danger” as desired. If the indication should be “danger,” trains cannot operate past the signal until the operator throws his control switch the other way.
The final type of signaling that is practical on the average model railroad is the block system. Tracks are divided into sections, or blocks, and each block is protected by a signal. If a train is in any one block, no other train can enter, but when the train leaves the block, the signal protecting that stretch of track goes to “clear” permitting another train to come in. Such a block system is purely an electric proposition. Model semaphore or color-light signals can be installed alongside the tracks, and connected to work with it, but they serve no purpose except as ornaments to make things more realistic. Electrical relays hidden under the baseboard do the work.
A block system as described above is not necessarily an impractical or highly complicated proposition, but it does call for careful planning and intelligent installation.