Re: the origins of 4' 81/2" standard gauge: There are more "urban
legends" on this subject abounding than Carter has pills. However,
all have some basic elements, however narrow, that have some ground
in truth. The basic fact to keep in mind is that standard gauge as we
know it is distinctly arbitrary, and results from an accident of
history.
Standard gauge of 4' 8-1/2" is what we know it today because that is
the gauge to which George Stephenson built his first railway
(Stockton & Darlington); and the reason that Stephenson chose that
gauge is that it happened to be the pre-existing gauge of the
long-pre-existing Darlington Collery wagon-way (tram way) for which
Stephenson built his first locomotive.
The Darlington line was just one of a vast network of wood collery
wagon ways around Newcastle that started to arise in about the 1770s
to enable coal to be more easily transported to the nearest water-
the only transport then available to supply fuel to the onrushing
Industrial Revolution..
These tramways were built to handle the freight wagons of the day.
Common wagon width would of course have been that which would
practically allow passage of two such vehicles on an ordinary road,
and what could ordinarily be pulled by a single horse, or two horses
side by side. The exact width of the axles would have of course
reflected this pragmatic "standard", but would also have would and
could have been a wide variety of widths.
As a result, these wood (and then wood and iron, and some eventually
iron alone) tram ways had no common standard. Some were as narrow as
about 4', while others were as much as 6' or more. Pick a number
between, and there was an excellent chance that there was a wagon way
for that gauge as well. One can only speculate on the reasons for a
chosen gauge in any instance, but it is reasonable supposition that
what was built depended upon the particular type of (road) wagons
that the collery had already in hand (or could purchase). A common
requirement, however, was that the "rails" had to be wide enough
apart to allow clearance for a file of single horses to safely
walk/trot down the center.
Just why the Darlington Collery line was originally built to 4'
8-1/2" is of course totally lost to history.
The overwhelming success, fame, and influence of the Stephensons
became such that their inherited and completely arbitrary gauge of 4'
8-1/2" became the eventual standard in England,and then in this
country. BTW, this was not even standard gauge here until Abraham
Lincoln made the momentous decision (1863?) that the Transcontinental
Railroad was to be built to this exact gauge.
Quite a bit of this information comes from a very thick English
scholarly work in my library on the wood tramways of England (not
currently in hand) purchased many years ago. I do hope that I have
recalled the details accurately.
Denny
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Denny S. Anspach, MD
Sacramento, CA
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