The relief line would connect St. Andrew station with Pape station. (TTC)

The TTC says that without a downtown relief line — a subway line to take some of the pressure off the Yonge and Bloor-Danforth lines — overcrowding on Toronto's subways will become the new normal.

A report to be presented at the TTC board meeting next week says that ridership in the downtown will grow by more than 50 per cent between now and 2031 and the city and the province have to make a downtown relief line (DRL) a priority.

The first section of the line, which would, according to the report, run from St. Andrew station on King Street West, along King and then swing north to connect with the Bloor-Danforth line at Pape station. The estimated cost of that section is $3.2 billion.

Currently, there is no money set aside for a downtown relief line.

"There's a number of revenue tools the City of Toronto has at its disposal, whether it's licensing fees, property tax increase, parking charges, so there's a number of things we're going to consult with the public on," said TTC Chair Karen Stintz.

Council's executive committee has given the green light for staff to start public consultations on implementing new revenue tools to fund transit expansion in the city and the Greater Toronto Area, although Mayor Rob Ford has said he opposes any new taxes or user fees.

Provincial body Metrolinx's Big Move transit plan for the Greater Toronto and Hamilton Area also has provisions for a Toronto downtown relief subway line, but it doesn't envision anything getting done for at least 25 years.

The TTC report published Wednesday says the Metrolinx timetable needs to be moved ahead by at least a decade.

TTC CEO Andy Byford stressed that building four LRT lines approved by council is something the commission "absolutely" wants to get on with.

"But equally, I would just like to just explore with my colleagues at Metrolinx — can we move up the order [of the DRL]?"

With files from the CBC's Jamie Strashin