The TTC’s success has landed it a $17.4-million deficit, a shortfall that could eat up potential savings from the summer civic workers’ strike.

Ridership is running at a record high, projected to hit 473 million rides this year, without even a recessionary dent. But revenue per passenger is lower because more people are buying cheaper, transferable Metropasses — at a loss to the farebox of about three cents a ride. Sales of discount senior and student fares are up as well.

Savings from the civic workers’ strike may be used to offset the TTC shortfall. Preliminary figures presented to the budget committee yesterday show the 39-day walkout saved the city at least $20 million.

However, that number doesn’t reflect costs or savings from the waste and water departments. The final tally will be presented to the executive committee Oct. 2.