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Yonge subway line faces early closing times

Stretch from Lawrence to Finch in need of repair

BY JUSTIN SKINNER
March 27, 2008 11:02 AM

TTC commissioners have adopted a recommendation that will see subway service end at 12:30 a.m. six days a week along a stretch of the Yonge line over the next two years.

The proposal, put forth at Wednesday’s TTC committee meeting, calls for all stations from Lawrence to Finch to close at 12:30 a.m. Sundays through Fridays starting in June until September 2009. The stretch of subway tunnel between the Davisville and Sheppard stations would then be closed Sundays through Fridays from March 2009 through July 2010. The TTC would run normally on Saturdays, and shuttle buses would pick up the slack left by the early closures.

The early closures will enable work crews to repair degraded and deteriorated sections of concrete lining within the subway tunnel. Should those segments not be repaired in the near future, the northern end of the Yonge subway tunnel could be at risk of collapse.

Warren Bartram, the TTC’s track and structure superintendent, said the work has been underway for some time, with workers spending a few hours every night reinforcing concrete liners within the tunnels. Because the subway runs from roughly 6 a.m. until 2 a.m. most nights, however, that gives workers little time to finish the work.

“The problem is the amount of time (work crews) have to work,” he said.

At the current rate of repair, the work could take until 2013 to complete. By giving maintenance workers more time with which to work, Bartram said he hopes to have all repairs completed by July 31, 2010.

Problems within the tunnel revolve around the fact that water and salt leeching through the earth have caused cracks and degradation along portions of the tunnel. Crews have already repaired the cracks, but must keep an eye out for new ones.

“You plug a leak here and it shows up down the track a little bit,” Bartram said.

Because the tunnel was installed primarily in the early 1970s, degradation is some sections is fairly advanced.

Complicating matters is the fact that as crews inspect portions of the tunnel and remove asbestos and other sound insulation from parts of the concrete lining, they continue to find new sections in need of repair. Bartram said this could impact the TTC’s timetable.

“As we clean off more (liners) and conduct a complete inspection, we’ve added more rings (that need repairing),” he said. “If conditions change dramatically, the 2010 date could change.”

Bartram stressed that the tunnels are currently safe, and are considered twice as sturdy as they need be to ensure that the tunnel will not collapse. That, however, is a marked difference from when they were first installed, when portions of the tunnel were 4.4 times as strong as needed to prevent cave ins.

“If we can keep the tunnel liners as good as they are right now, then it’s safe to continue operating,” Bartram said. “If they get worse, then we can’t ensure that the tunnels will remain as safe as they should be. The concrete’s two times as strong as it needs to be, but that’s not a lot in engineering terms.”

The early subway closures are expected to affect as many as 29,000 riders per week, though TTC chief general manager Gary Webster said it was a necessary move.

“We believe 12:30 a.m. is late enough in the evening, and traffic’s light enough at that time that it’s the best time to do this,” he said. “At midnight, 12:30, we’re down to less than 1,000 riders a night at that time.”

TTC commissioner and Ward 8 (York West) Councillor Anthony Perruzza said that simply reinforcing concrete made it seem like the committee was “sticking a Band-Aid over something that has potential structural issues over it.” He said this seemed particularly true given the fact that the tunnel has changed in shape over the years, going from a round tunnel to a more squished, egg-shaped one.

Webster, however, said that the tunnel does not seem to be becoming any more compressed, and that the maintenance work being done, which includes spraying the reinforced concrete with a protective spray, would be a marked improvement over current conditions.

“Is this a long-term repair? Does this extend the life of the tunnel? The answer is yes,” he said.

Even after work is complete, the TTC will continue to monitor the tunnels, including regular inspections by leading engineering experts.




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