A track problem has forced the TTC to take streetcars out of service on one of its busiest downtown commuter lines.

The TTC has temporarily taken all 501 Queen Street streetcars off their tracks and is running buses instead after crews noticed several streetcars’ brake systems had been damaged, according to TTC officials.

Communications specialist Stuart Green said TTC crews noticed the damage overnight and began pulling the streetcars from the route around noon.

“The 501 line is operating with buses until such time when we feel it’s safe to put streetcars back on the Queen Street route,” Green said.

About 35 streetcars typically run the 501 route during rush hour. The TTC is planning to have 90 buses fill that void, Green said — slightly less than their rated capacity of three buses for every one streetcar.

Green recommends passengers who regularly take the 501 Queen Street streetcar consider taking a different route until they are running again.

The TTC has deployed added additional vehicles to the 504 King Street route and the 506 Carlton Street route.

Green said there is no timeline for when the streetcars will be up and running again, but said the TTC hopes to solve the problem by Thursday morning’s rush hour.