that horse's arse thinggy

[Bryn Watkins <bryn@tibinc.com>]

Poster: Bryn Watkins <bryn@tibinc.com>

I am also on a motorcyclist list, and that list finally received the
standard on train gauges, and while I suspect an eruption about it is
imminent there, this is what our resident brit says about it.
>a biker quotes:
>>The US Standard railroad gauge (distance between the rails) is 4
>>feet, 8.5 inches. That's an exceedingly odd number. Why was that
>>gauge used? Because that's the way they built them in England,
>>and the US railroads were built by English expatriates.
>
>Not that I want to dampen a plausible urban legend (it well may be
>that the final gauge settled on was the Roman one), but it's more
>complex than that.  This happens to be one of the few things in my
>history classes that I was actually interested in, so I remain
>somewhat informed on it.
>
>During the early years of the railroad in England, every railroad
>company used a different gauge.  Most were around 5 feet, give or take
>a bit, from 4'8.5" to around 5'6" (if I recall correctly).  For quite
>some years rolling stock was actually built to account for gauge
>changes -- you could switch from one gauge to another by moving the
>wheels on the axles.  Obviously, though, with the integration of the
>rail system this was not a tenable situation, and the need came to
>standardise on a single gauge.
>
>Why settle on 4'8.5"?  Because it was the *smallest* gauge of those
>major railroads at the time, and so picking anything larger would have
>entailed rebuilding a vast number of tunnels and bridges to allow for
>the wider trains.
>
>It's not as romantic as the Roman theory, but it has the alternate
>benefit of being fact. ;-) Of course, the company who plucked 4'8.5"
>out of the air in the first place *may* have picked the Roman chariot
>dimension, but if so it was probably by coincidence.  "3.5 cubits" (or
>whatever it was) can be approximated to anything from 4'6" to 5'6" or
>so...
>
>
>A side note:  the great engineer, Isambard Kingdom Brunel, eschewed
>these namby-pamby gauges and picked one for the Great Western railroad
>on *engineering* principles (what a novel idea!).  As I recall it was
>7'.  Here's your standardisation moral:  the standard gauge was chosen
>as the lowest common denominator -- had the railroad chosen 7', we'd
>now be reaping the benefits of larger freight volume and higher speeds
> on most high-speed railroads, the *rail* specifications are the
>limiting speed factor).
>
>>and the US railroads were built by English expatriates.
>
>To give credit where it's due, most railroads in England were actually
>*built* by poor Irish labourers forced to seek work in a richer (and
>less hungry) country.
>
>Martyn
> --sasmjw@unx.sas.com--(Martyn Wheeler)--SAS Institute Inc.--DoD #293-BGFY#
****************************************************************
Bryn Watkins                            
Tiburon, Inc. 
3333 Durham Chapel Hill Blvd. E100       919-490-0034
Durham, NC 27707                         http://www.unc.edu/~watkins/
Be kind to dragons, for you are crunchy and go well with ketchup!

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