The subway operators thought they’d made contact with something as they rolled up the Yonge line, but weren’t sure what. It turned out to be a drill bit. Up on the street, meanwhile, a work crew was reaching an awkward conclusion: It had accidentally broken into the tunnel far below.
The drill bit was barely a dozen centimetres across – roughly as wide as a pocket paperback – but had a lasting impact on Tuesday. The construction mishap shut down a heavily used section of the country’s busiest subway line, from St. Clair to Lawrence, for hours as the evening rush approached.
“They called us and said, ‘Uh, we think we’ve drilled through your tunnel,’” Toronto Transit Commission spokesman Stuart Green said.
“People went down there and had a look and they thought at first it was like a part of the tunnel had just sort of cracked or the concrete had fallen away or something. But they then found out that there was this hole being drilled from street level. So we put all of that together and figured out that’s exactly what it was.”
A temporary patch was in place by 6:30 p.m., about four hours after the incident happened, Mr. Green said. But this section of line would still have to be closed early Tuesday night to facilitate a proper repair, affecting fans returning from the Toronto Raptors home opener.
Although workers are supposed to research possible utilities before digging – and on this occasion had a permit to go 50 metres down, the TTC said – mishaps can still occur. This is the third time in a decade that a worker has accidentally broken into the subway.
In this case, the job was being done by a private company and the work was unrelated to the subway itself. A spokesperson for Metrolinx said it was not connected to the light rail line being built along Eglinton.
It’s not clear the exact nature of the work being done – the company whose name was on a truck at the scene did not return a call early Tuesday evening – but a TTC official said it appeared be soil-sampling or geo-technical analysis.
Whatever it was the crew was after, it was drilling deep. Although the Yonge subway is barely below the surface in much of the downtown, and above ground in places, it goes deeper as it heads north. After Eglinton station, the tunnel drops down to reach the station at Lawrence, which sits in a small valley.
During the disruption the TTC activated a protocol that allows their users to ride GO Transit for the same fare. It also put on nearly 100 buses to shuttle people through the closed section of the subway, while its crew was down below assessing the damage.
“We have to figure out if we can plug it and then secure and make sure the tunnel liner isn’t compromised,” Mr. Green said.
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