Path: utzoo!censor!becker!eric
From: eric@becker.UUCP (Eric Siegerman)
Newsgroups: tor.general
Subject: Re: TTC Subway fault-tolerance
Summary: Subway power-zoning hypothesis
Keywords: TTC, Subway, delay, fault,turn-around
Message-ID: <383@becker.UUCP>
Date: 23 Mar 89 08:15:49 GMT
References: <810@mv03.ecf.toronto.edu> <446@ontenv.UUCP> <1989Mar20.211818.27937@sq.com>
Reply-To: eric@becker.UUCP (Eric Siegerman)
Distribution: tor
Organization: There ain't no organization here.
Lines: 37

In article <1989Mar20.211818.27937@sq.com> msb@sq.com (Mark Brader) writes:
>> Wednesday's problem made it necessary to shut off power to the rails, I'm
>> pretty sure the power is "zoned" but likely Davisville and St. Clair
>> are in the same zone.  There are certianly other reasons too.
>[...]
>Eglinton station has turnback switches on *both* ends
>[...]
>but it must be in the same zone too.
>[...]
>Apparently because Bloor is in the same zone too.
>[...]  So it seems there was no power on the
>Yonge line at Bloor either.

According to a friend of mine, who once worked as an inspector of
equipment in the subway stations, the emergency power cutoff
switch (there's one at each end of each subway platform, with a
blue light and dire warnings as to the consequences of misuse)
cuts power to trains in both directions, at the station in
question and at the two adjoining stations (ie. a total of three
stations are affected).

This suggests that each station is in its own zone, with the
cutoff switch sending a control signal to the neighbouring
stations.  Two- or three-station zones would not seem to permit
the interlocking scheme I've described.

A way to test this hypothesis:  when riding in one of the old red
subway cars with the incandescent lighting, see how often the
lights go off.  I've always assumed that they flicker when the
train crosses the insulated gap between zones (and that the newer
cars' lights don't flicker because they are equipped with
batteries -- necessary because fluorescent lights would take too
long to come back on once power was restored.)

-- 
Eric Siegerman, Toronto, Ont.
eks@kneller.UUCP,  eric@becker.UUCP,  ...!utzoo!mnetor!becker!kneller!eks