From: msb@sq.sq.com (Mark Brader)
Subject: Re: toronto subway gauge
Organization: SoftQuad Inc., Toronto, Canada
Date: Wed, 7 Oct 92 23:16:25 GMT

In an article with an invalid Distribution line, we see:
> The fascinating things you learn on this net!  I never suspected that
> the Toronto subway and tram systems used a non-standard gauge (4 ft,
> 10-7/8 ins) ... Whatever made the builders pick **that** gauge? 

Hmm, I think I've posted about this before.  The reason for the particular
gauge is lost in history -- the only explanation I've seen is that it's
exactly 1500 mm, which is (a) historically unlikely, and (b) wrong, as
the correct equivalent is 1495 mm.

The reason the streetcar tracks were built to *some* nonstandard gauge
was to make sure that, no matter what the politicians wanted to allow in
the future, it would *never* be economically feasible to route *trains*
(with those horrible steam locomotive things) along our fair streets.
This was a reasonable worry, considering that in those days a fair number
of places had such routings; there are still a few of them today.

Then, when the initial segment of the subway was built, it wasn't felt
worthwhile to have a place for doing major overhauls of the motors
and such; instead, the bogies ("trucks") were removed from the subway
cars and towed along streetcar track to a carhouse.  If the subway
used a different gauge, this trick would require more equipment.  (It
stopped happening in the 1960s when the subway grew larger and separate
overhaul facilities become worthwhile.)

Incidentally, the people who made that original gauge decision probably
didn't realize that the entire system of streetcar tracks would be torn up
and relaid later -- the tracks had been set too close together to accommodate
the later cars.  However, they were rebuilt to the same gauge, so that the
existing cars could be used alongside the new Witt model.  This was in the
early 1920's.

> It's so close to the standard 4'8-12'' that I can't see any obvious
> advantage in being different.  It'd certainly make it harder to sell
> off obsolete equipment.

Actually, standard gauge is often 4 feet 8 3/8 inches these days, on
lines with superior track standards.  The wheel flanges are at 4 feet
8 1/4 inches in either case.

Having decided to choose a nonstandard track gauge for no reason other
than incompatibility, it seems clear that a gauge slightly wider than
standard is best: standard gauge equipment can be converted at a relatively
small cost by simply moving the wheels out a bit.  If want to sell it, you
you just move them back in again.  Incidentally, the Halton County Radial
Railway streetcar museum has similar quantities of what were TTC and
standard gauge vehicles, or did when I last visited; and their track is
TTC gauge.

Pittsburgh also has a nonstandard streetcar gauge; someone might like to
comment on how many of the above issues also exist there.
-- 
Mark Brader, SoftQuad Inc., Toronto, utzoo!sq!msb, msb@sq.com
	A standard is established on sure bases, not capriciously but with
	the surety of something intentional and of a logic controlled by
	analysis and experiment. ... A standard is necessary for order
	in human effort.				-- Le Corbusier

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