Commuters had to wait as long as an hour for northbound shuttle buses at the corner of Bloor and Yonge streets on Wednesday evening, after the TTC shut down subway service between Bloor and Eglinton stations. (Robin Rowland/CBC)

Toronto commuters were back riding the subway Thursday morning, but some were still fuming over an accident Wednesday afternoon that threw the city's public transit system into chaos.

Just a day after learning the Toronto Transit Commission intends to hike fares in January, one of the city's most important public transportation routes was closed.

"It's very ironic," said TTC rider Sarah Twomey, "and it's just going to add to a lot of frustrated Torontonians. On every single level, Torontonians are really, really angry — very angry. And this is just one more thing."

The TTC wasn't directly responsible for the six-hour shutdown. Initial reports blamed the problem on a contractor who cut into the subway tunnel by mistake. Fearing that could lead to structural problems, the TTC shut down service on its Yonge-University-Spadina line between Bloor Street and Eglinton Avenue — a four-stop stretch of subway used by hundreds of thousands of commuters every day.

Instead of subway cars, passengers were moved up Yonge Street by 50 shuttle buses. But the process was a slow one, with huge crowds waiting outside every subway station waiting to board and make their way home.

From 3 p.m. to 9 p.m. the overcrowded buses moved north and south in a steady stream.

The TTC said the problem started with bridge repairs above a subway tunnel just south of the St. Clair station.

A contractor not associated with the transit authority was "cutting about an 18-inch-wide [46-cm-wide] trench — the kind of trench you see for laying cables and whatnot — not realizing that below that roadway was a subway tunnel," TTC spokesman Brad Ross said.

The TTC had "real concerns" the weakened portion could collapse into the tunnel, he said.

The TTC also intends to "sit down with the contractor [and] look at what we need to do to ensure that the tunnel is safe and it is structurally sound. Right now the fix, of course, is temporary, but safe enough to operate the subway. So again the long-term solution we have yet to determine," Ross said.

Torontonian Carline Carpenter may have been the only one of the thousands affected who saw the bright side.

She didn't wait to find out how long she'd have to wait for a bus; she just started walking. "You know, I didn't check to find out. I just thought, 'Exercise!' "