Model Railroading Rail Weights and Codes
There is one other
measurement for track that is important. On a real railroad, the actual rails
are rated by their weight per yard, which loosely translates to how the rail is
to be used. Heavier rails will be used on high speed main line areas, where a
lighter rail will often be used in a lower speed or less heavily traveled
siding or yard area. Real rails typically have a rail profile height somewhere
between slightly under five and slightly over seven inches, depending on the
railroad and the standard that it uses. If we were to model the exact rail
profile in N-scale, the height of each rail should be between about .031 and
There’s no ‘weight’
measurement in model railroading, but there is a ‘code’ description. The code
of the rail refers to the actual rail height in thousandths of an inch above
the tie. In N-gauge track, you will see Code 40, 55, 65, 70 and 80 which
correspond to .040, .055, .065, .070, and .080 inches tall. You can see that
the only rail code that matches actual real world railroads would be code 40.
However, this poses a problem that is not unique to N scale
It’s important in both real
railroading and modeling for the trains to remain on the tracks. Modern
prototypical railroad cars have wheels that have a rim, or flange that holds
the wheel on the rails. Modern cars are also heavy, and the combination of the
flange and the weight of the car generally keeps the car on the track. In
modeling, the wheel sets also have a flange, but the weight of the car is not
proportional to the weight of the real thing. To compensate and keep our small
trains on the tracks, the flanges on the wheels are much larger than scale.
This is where the rail height comes into play. A code 40 or 55 rail may cause
the flanges on some cars, particularly older ones, to ride up over the ties as
the car moves, promoting rather than reducing derailment.
There are replacement
trucks and wheel sets available for most rolling stock, but the wheels of
locomotives are not generally easily replaced. Some modelers have reported
success in machining their locomotive flanges to a smaller diameter, but this
is a very advanced modeling technique that also requires specials tools and
skills. A much easier solution is to use a larger code rail and try to divert
the viewer’s attention from the inaccurate proportion.
Code 55 and code 80 rails
are the most commonly seen layout standards. Both come in fixed rail and
flextrack products. Manufacturers such as Peco, Shinohara,
Micro-Engineering provide a complete range of products for mainline track as
well as turnouts, crossovers, and other special arrangements.
It is possible to mix
manufacturers on a layout, but careful attention has to be paid to the
transition between different types and codes of track. At the very least, some
shimming will be required to match the railheads precisely enough to prevent
derailing. Mixing products is not a good idea for the beginner, however, and it
would be wise for you to build a layout or two with homogeneous products before
trying to mix and match.
Like other scales, it is
possible to hand lay N scale track. If you are a beginner or have poor eyesight
and hand-eye coordination, hand laying may not be for you. If it seems
attractive, try creating a small diorama with hand laid track before committing
to a substantial layout project. There are tools and jigs available from most
model railroading hobby suppliers that will help the process, but it is work
intensive to say the least. The up side is that it can be marvelously realistic
if done well!
Now that the gauge-scale
issue should be clear, N-scale will be the convention used for the remainder of
this piece. However, before we move on to that, it is worth quickly explaining
another point that confuses many who are new to the hobby.
Enjoy your N scale
railroading, and get the two books shown at the top of this page. You'll find
then really helpful.