Track Basics

This article first appeared in the November/December 1993 issue of AMRA's 'Journal'.
By Stephen J Chapman.

Railway track is something that we run trains on. We buy the track, we lay it on the board, and we run the trains.

It sounds so simple. Actually there are quite a number of things that need to be considered when we look at railway track.

 

Not all prototype track is the same. To start with there are a number of different rail profiles in use. The most common rail profile is called flatbottom rail (figure one), bullhead rail (figure two) has also been used on occasion. The idea behind bullhead rail was that by having the same profile top and bottom, the rail could be turned over when the top was sufficiently worn, doubling the life of the rail. This did not work out because as soon as a train was run over the track the chairs distorted the bottom of the rail making it impossible to use the rail the other way up. Both of these rail types are available in model form.

figure one flatbottom rail flatbottom rail figure two

A fairly obvious difference in prototype track is the type of sleepers that the rail is laid on. Wooden sleepers are common. Concrete sleepers are becoming more common. Both of these two sleeper types are available in model form and are normally represented by coloured plastic. Sleeper spacing can also vary from one prototype to another with narrow gauge branch lines often having a slightly wider spacing. The broad gauge of the GWR in England was laid on sleepers with a completely different orientation.

The track gauge is another obvious difference. Standard gauge and some narrow gauge tracks are readily available in model form while other gauges (particularly the broad gauge) are not. In some cases it may be possible to use a track intended for use as standard gauge in one scale as a narrow gauge track in a larger scale. In this case the sleepers will probably be too narrow and much too close together. This discrepancy can be disguised to some extent when you ballast the track.

 

The size of the rail also varies between main lines, branches, and sidings. The size also was varied over time, becoming more substantial as the size and weight of trains increased. This size is usually given as a weight for a given length of track. 100lb track is more substantial than 80lb track. In model form the size of the rail is indicated by a "code". This code is the height of the rail expressed in thousandths of an inch (Code 100 is l/10 inch). It is rare that a layout is built using more than one code of track but it can be done.

Most scales have a number of different codes of rail available for use with them. This is because larger (coarser) codes were used in the past, different manufacturers make rail that is different heights, and closer to scale codes (usually smaller) can be used with some wheel standards than can be used with others. An example of codes of rail available and how things have changed over the years, in HO. Triang super-4 track which was produced during the 1960s was code 140. Code 140 is now normally only used for O gauge. Peco and many other track manufacturers now produce track for HO that is code 100. Peco have also produced track using bullhead rail to code 90. Shinohara track is code 70. This is only half the rail height of the earlier Triang.

A similar range of codes is available in N gauge. Code 80 is the most commonly available but code 40 is also available. Peco have cheated a bit with one type of track by setting code 80 rail into the sleepers so that it looks like code 55.

 

The type of ballast that the track is laid on also varies from one line to another. To model this aspect mostly means choosing the right colour ballast to use.

The ballast on the prototype serves a number of purposes among which are helping to hold the track in place and drainage. The ballast is not completely flat across the tracks. There are a number of places here the ballast dips down into drainage trenches on either side of the tracks (see figure three).

flatbottom rail
figure three

 

If you go out and look at a section of real track you will notice that it is not all nice and neat and tidy like you see on many model railway layouts. There are weeds growing up through the track, more on little used sidings and less on main lines. There are piles of sleepers alongside the track. There are lengths of rail laying alongside, or even between, the running rails. These rails may be either old rails that have been replaced, or new rails waiting to replace the existing ones. In either case the rails usually have a somewhat rusty appearance.

Even the running rails themselves have a rusted appearance on those surfaces that the wheels do not come into contact with. The appearance of your model track work will be greatly improved if you paint the outside of your rails a rusty colour. Be careful when painting not to let the paint on the top or inside of the rail or you will have pickup problems when you come to start running your trains.

Look at where tracks cross bridges and other similar features. Quite often you will see that check rails have been fitted between the running rails to ensure that trains do not derail on the bridge.

 

Model track these days usually uses nickel silver rails. This type of rail has the advantage that it appears to be the right colour for shiny new track and it doesn't rust. Track is also available using steel rails which will eventually rust if exposed to moisture. Steel track allowed Triang to install what they called "Magnahesion" in their locomotives (ie. a magnet between the wheels). This gave the locomotive a better grip on the steel track and permitted the weaker motored locomotives to haul a longer train. Brass railed track has also been produced at a price intermediate between the cheaper steel track and the more expensive nickel silver. Brass track also doesn't rust, unfortunately the rail colour leaves a lot to be desired.

 

Model turnouts come in three basic varieties. There are the (so called) live frog turnouts which have metal rail throughout. The "frog" of a live frog turnout is switched to the appropriate polarity to match the appropriate point setting (figure four) and any train on the other track is therefore isolated because both rails have the same polarity. Live frog turnouts have the advantage of minimizing rail gaps and hence the chance of a locomotive stalling on the turnout. Dead frog turnouts have the "frog" moulded in plastic. There are two varieties of dead frog turnouts. These are isolating turnouts (figure five) and permanently wired (figure six). Dead frog turnouts allow you to simplify the way in which you wire your layout.

live frog
figure four
 
dead frog - isolating
figure five
 
dead frog - premanently wired
figure six

 

Other features may need to be built into the track work before or during the time that you are laying your track. Some uncoupling ramps need to be fitted below the track or come ready built in their own separate piece of track. If you are going to be fitting ramps of either of these types then you will need to determine where you will want to be able to uncouple your trains prior to laying the track. If you are using a type of uncoupler that fits on top of the track then you will not have this problem and will be able to decide where to put the uncouplers after you have laid the track and possibly even shift them if their locations don't suit the operating pattern.

 

You can buy all of your track ready made (if the type of track that you want is available). You can buy the component parts (rail, chairs, sleepers) and make the track yourself. You can make the sleepers yourself from (for example) wood or printed circuit board. You can use a combination of all three methods.

Which method that you use depends on

  1. the scale that you are working in,
  2. the effect that you are trying to achieve, and
  3. the availability of ready made track and/or component parts required to achieve that effect.

Track is not just something to run your trains on, it will add to or detract from the overall effect of the whole layout.

 

The way in which you lay your track is also important. Care is required to ensure that your straight track is at least reasonably straight and that you don't have any kinks in the track on which the trains might derail. The spacing between the tracks on double (or multiple) track lines needs to be properly maintained. Minimum radius curves need to be double checked to see that they are even and don't get too tight at one point.

Sleeper spacing needs to be maintained across rail joins. Too many times on model railways we see rail joins with a wider than normal sleeper gap under them. On the prototype the sleeper spacing is normally less under rail joins to what it is elsewhere. With plastic sleepered track it is a simple matter to cut away the moulded chairs on the sleeper on either side of the join to make room for the rail joiner without having to leave an unsightly gap.

Gauges of various types are available to assist with track laying. There are a number of different types available. One type of gauge checks the track itself to ensure that the rails are the correct distance apart and that check rails are positioned in the right place. Another type of gauge ensures that the correct spacing is maintained when laying double track (this type of gauge can be created by yourself by cutting slots into a piece of wood). Tracksetta gauges are available in a number of scales to allow curves of specific radii to be laid effortlessly and accurately.

The tracks that you lay should be checked thoroughly using all of the appropriate gauges when it is first laid and again once all of the ballast and other scenic features have been added. This will ensure trouble free running.

When fastening down track, drill holes in the sleepers to put your track pins through. Don't just force the pin through the plastic (unless you are using the type of tool specifically designed to insert the pins this way). Leave the top of the pin slightly above the sleeper. If you force the pin right in then the sleeper may be bent downwards and the track gauge will be affected.

Cut rails through cleanly. A razor saw or appropriate power tool (eg.Dremel) will cut through the rail. A sharp knife can be used to cut through the plastic sleeper webbing and to trim chairs so that joiners can be fitted. If you need to cut through a track that crosses a board join then make sure that you cut each rail perpendicular to the rail itself (NOT parallel to the edge of the board unless the track crosses the board at right angles).

Your tracks will need cleaning regularly. Access to clean tracks inside tunnels will need to be maintained otherwise those tracks will slowly get dirty and trains will tend to stall inside the tunnels (the worst place to try to reach them to get them going again). The simplest way to clean the tracks is using a track-rubber. Track cleaning fluids may also help and can even be deposited on the track by specialized track cleaning wagons. High frequency generators are also available to help trains over slightly dirty spots.

 

Choosing the right track and adding all of the smaller features seen on the prototype can turn a piece of rather plain looking track into a scenic feature in its own right.

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Copyright Stephen Chapman