Fahrzeuge und Gleisbau:Oberbau/en

Trackwork

The trackwork on light railways is, as the name already says, kept light, since there are usually no heavy axle-loads. In addition it should be easy to lay tracks, especially when track often has to be moved, as for example in sand-pits.

Ties can be made from wood and steel. The usage of concrete-ties on light railways is uncommon.
Steel-ties have the advantage, that the mounting-base for the rails is already provided. With light rails it is possible to mount rails and ties to prefabricated frame-track, which can be handled as a unit. These frame-tracks are easily laid or taken up. Their usage is preferred on construction sites or military light railways, where the track-layout is continuously changing. A special rail-type is named "Patentgleis", where the track-frames are not boltet together but simply snaped together like the snaptrack on model-railroads. It was preferred by farm- and logging railways. Steel-ties in addition have a better durability, especially when completely covered with ground - by the way, a little rust-proofing won't do no harm.

Wood-ties on the other side have the disadvantage to rot gradually, even if correctly treated. Their advantage is only the ease of handling. They are simply cut with a (hand-) saw and simply drilled for the tie-fastening-screws. From experience can be said, that standard-gauge ties cut to half-length provide a strong trackwork, while light railway ties made from steel are too light to hold the track permanently in alignment. The base for the rail is significantly longer with wood-ties and a tie-length of approximately 1.3m (4' 3") also gives a good crosswise stability. The maximum wheel-load (= 1/2 max. axle-load) on wooden ties of aprox. 5 to 5.5 in. is the same as with roof-ties type 175/9. The maximum tie-spacing remains 100 cm (39-3/8") even when lighter rolling-stock and rails are used.
No matter what kind of tie used, they are laid .5m (20") to 1.0m (39") apart, depending on the load-bearing capacity of the ground and the used axle-loads.

Usually the rails are fastened to steel-ties with bolts, and sometimes with additional clamp-plates.
The simplest method of fastening rail to wood-ties is the use of rail-spikes. These spikes have the disadvantage to loosen due to the rail's movement under load, so that they have to be respiked from time to time. Better experience has been made with screwed on rails. Therefore one screw is driven into the tie on the right and left side of the rail respectively, in which the use of additional tie-plates is not necessarily recommended. Only stretches of rail exposed to heavier loads, like turnouts and curves, the use of tie-plates is recommended. If no special tie-plates are available, it is absolutely sufficient to use some flat steel or sheet-metal of 3 to 5mm (1/8" to 3/16") thickness cut to size.

The rails of light railways are usually bolted together using fishplates. To weld the rails together would bear the danger that the rails would bend out of alignment when becoming warm, i.e. in summer, for the trackwork used on light railways is simply to light, and the missing play in the rail-joints won't allow for any compensation in length-changes.
Fishplates are available in a flat and an angled variety. The angled fishplates provide better stability against kinking in the rail's longitudinal axis, i.e. in curves.

Curves

The radii used on light railways are dependant on the landscape. Nonetheless it also applys to light railways, that radii are to be kept to the maximum possible, to minimize the wear on rail and wheel and avoid the danger of derailments.
In general the minimum radius of a railroad is dependant on the used equipment and the speed. The speed on light railways can be neglected. In respect of the equipment can be said, that the minimum radius is increased according to the increasing number of axles and an increasing wheelbase. The minimum radius locomotives can take is normaly supplied with the builder's manuals.
Attention must be paid to the fact, that the gauge has to be widened in curves. This widening is dependant on the radius and the fixed wheelbase, increasing the amount of widening with tighter radii and longer fixed wheelbases. On the other hand it is essential to observe the wheel-width of any car, to prevent smaller cars or such with narrower wheels from dropping between the rails.
If several opposing curves follow immediately behind each other it is essential to include a piece of tangent track between any two curves. The tangent should be at least as long as the longest piece of rolling stock, to allow any piece of equipment to first straighten before rounding the next curve.