A week ago this morning, a fire broke out near York Mills station,
knocking out subway service on the north part of the Yonge line for almost
an hour. Trains were back running by 7 a.m., but some riders had to
evacuate the train in which they were riding, and many tried to board
buses that were reassigned from nearby routes.
On Tuesday, Nov. 18, another fire affected the north Yonge
line, cancelling service until fire crews ensured there was no danger. In
both cases, a wooden board over the electrified third rail caught fire,
sending smoke through the subway tunnel.
Gary Webster, the TTC’s manager of operations, says that
while both fires involved these “coverboards”, the causes were different
and the TTC is taking steps to ensure such incidents don’t occur again.
Smaller fires happen more often when paper contacts the electrified rail
and ignites, but these usually result in only minor delays.
Ever since a serious tunnel fire in 1997, the TTC looks
closely at combustible products in the tunnels, but Mr. Webster says the
recent coverboard incidents are not part of a trend. “This is a new
problem -- this is not an ongoing problem that we’ve had.”
The wooden planks, which do not conduct electricity, protect
track maintenance employees from coming in contact with the third rail
from which the trains get their power.
The fire in November occurred when a corroded metal support
holding the board in place broke, and the wood came in contact with the
power rail. The metal rusted because of a nearby water leak in the tunnel,
a relatively common problem that the TTC is currently fixing right across
the underground system. Crews inspect the subway system every 72 hours,
checking the supports, coverboards and rails, but “we missed it” says
Webster.
“This is something we should have noticed and we did not.
TTC has to accept responsibility for that. We’ve inspected, subsequently,
the whole subway system with that particular view in mind to see if we
have any other... leak locations with similar problems. We found two or
three and the coverboard was removed and the repairs have either been made
or will be made as soon as we can do so.”
Ironically, the more recent fire last Friday may also have
been caused indirectly by water. The TTC cleans its subway tunnels with
high pressure hoses, which wash all manner of dust and other junk
(including human hair) into drains. Webster says that some of this
detritus may have wrapped around the ceramic insulator that holds up
the electrified rail.
“We believe that... there was an accumulation of dirt and
guck that built up... and the combination of the guck and the water became
a conductor. The electricity found a path around the insulator and...
overheated the insulator. A small fire took place, and that caused the
coverboard to combust.”
He says that officials are now examining the way the TTC
washes the tunnels, as well as the possibility of using different
materials than wood for the coverboard. As part of a strict examination of
all such emergencies, the TTC is probing the causes and possible
prevention of similar incidents.
Subway closures, especially during rush hour, can
inconvenience many thousands of riders caught underground, as well as
customers whose buses are used to replace trains in what the TTC calls a
“subway bridge.” Closures due to events such as the recent fires occur
only every few months, but buses simply can’t fill the gap.
Says Webster, “When you’re running a subway service every 2
minutes and 25 seconds, you need a lot of buses. The problem we have is,
we simply cannot provide acceptable replacement bus service when the
subway goes down.”
The TTC’s heaviest bus routes can move 2000 to 2500 people
per hour in one direction -- the subway’s capacity is ten times that. Say
Webster, “All you can do is do the best you can, put buses out there, and
communicate with the public. Hopefully the delay will not be that long and
they can get back on the system.”
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