[net.railroad] Gauge and Scale

hanss (01/08/83)

I'm surprised no one has answered the requests that have been appearing
over the last few days to explain what all the scale and gauge stuff in
model railroads is, so here goes:

Gauge is the separation between the wheels or rails.  American
railroads, and much of the rest of the world too, use a standard gauge
of 4' 8.5".  This happens to have been the gauge of the Roman chariots,
and during the mid 19th century when the standard was being adopted was
considered quite wide, and therefor stable and providing a smooth
ride.  For various reasons other gauges have been used various places,
mainly to fit in narrow mountain cuts, or to provide an especially
smooth ride.  Of course they are incompatible with everywhere else, and
the narrow gauge railroads had to go through pretty remarkable
contortions to move freight between their areas and the rest of the
country.  The great god compatibility looms his ugly head everywhere!

Scale is the ratio of a models size to the prototype.  When model
trains began appearing in the late 19th century standard scales were
used, and these scales were numbered in increasing size, 0, 1, 2, etc.
Scale 0 was 1/48 of the real size, and used a 1.25 inch gauge.  A
little arithmetic shows that 1.25 inches is a scale 5 feet, a little
bigger than the real thing.  And with a little lazyness, you can see
how '0' got turned into 'O'.

As technology improved and modelers became more critical,  correct
gauge O scale models were developed, not only for standard gauge but
for narrow gauges as well,  Smaller scales were developed, now
attempting to be correct correct gauge for the scale , but of course
always sacrificing something for the sake of reliability.   S scale was
developed by American Flyer at 1/64 real size.  HO (Half O) was
developed in America at 3.5 mm to the foot for 1/87.1 scale and 00 in
England at 4 mm to the foot, both advances coming, I believe, during
the '30s.  Brain damaged mixed measurements apparently stem from
feeling the need to step up to 'modern' metric units without really
understanding the point of the modern measurements...

In the 50's, TT (tiny trains) were developed at 1/120 scale, but they
never caught on.  In the late 60s N scale, at 1/160, almost half the
size of HO, was a very big hit, particularly in the toy train market.
I understand there is a move afoot to go even smaller.   Last I heard
HO was still the most popular, and I'm sure the people that are
concerned about precise to scale modeling will stay there or larger.

To the people asking these questions, I greatly recommend Model
Railroader or one of the other magazines available from your hobby shop
or by subscription.  Among other things they provide a very good list
of hobby shops that carry a lot of train stuff, and more magazines.
While I no longer subscribe or build trains (building compilers and
video games is even more fun!)  I learned a heck of a lot, including a
lot of simple electronics, use of tools, and other stuff too numerous
to mention from reading them during my adolescence.

				-Hans Spiller
				decvax!microso!hanss