A busy stretch of the Yonge Street subway line could be closed for up to two months as the TTC contemplates badly needed upgrades to the aging tracks between the Eglinton and St. Clair stations.

The transit commission hasn't yet decided how or when to proceed with the track replacement, but one possibility involves temporarily shutting down the Eglinton-to-St.-Clair portion and running shuttle buses along Yonge Street between the stations.

"Anyone who uses the Yonge line between those two stations... knows that it's a very frustrating ride. The trains have to creep through that area very slowly," TTC CEO Andy Byford told CBC Radio's Metro Morning this morning.

"What we have to do at some point yet to be determined is completely replace that stretch of track... It's a big job, but I won't give the go ahead until I'm certain that we've found the best way to do it — in other words the way that will inconvenience customers the least."

One idea Byford floated involves converting a lane of traffic into a dedicated bus lane for the duration of the project and running "a fleet of buses" along Yonge. Byford said the city and police would have to be consulted first.

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TTC CEO Andy Byford says he won't give the OK for a major, disruptive shutdown on the Yonge Street subway line until 'I'm certain that we've found the best way to do it.' (CBC)

It's unclear how long the work could take or when exactly it will happen. Byford said his best guess was it will take "probably between six weeks and eight weeks," adding that "if there's a quick way of doing it, that's the one we'll choose."

He said the transit commission is looking to nail down a proposal for the timing within the next couple months. "They'll then be an extensive communication and consultation period."

The TTC will obviously avoid doing the repairs during the 2015 Pan Am Games in Toronto, Byford said, but other than that not much has been determined.

"It may well not be 2014," he said.

The tracks on that stretch of the Yonge Street subway line are 60 years old, which is years beyond their originally expected lifespan.