Subway riders hoping to come downtown this weekend will need another plan . The TTC is shutting down the downtown portion of the subway – between Bloor and St. George Stations on the Yong-University-Spadina line -- for the entire long weekend.

The subway line will be shut down for signal upgrades, according to TTC officials.

As a result, trains will not be running north or south on the ‘U’ portion of the line between Yonge-Bloor Station and St. George Station between Saturday at 6 a.m. and Tuesday at 6 a.m.

During that time, shuttle buses will be running between the affected stations to replace regular subway service.

“The only way we can get done the work that we need to do this weekend is by closing the subway,” TTC spokesman Brad Ross told CP24 Wednesday.

Ross said that while the TTC tries its best to carry out repairs and upgrades during periods when the subway is closed to riders, the signal replacement work requires a longer stretch of time to complete.

“We do a lot of work overnight when the subway is closed for routine maintenance, but we do need a prolonged period of time that a long weekend gives us for this particular piece of work.”

The upgrades on the ‘U’ portion of the line are part of a larger upgrade that is expected to be complete on the entire line by 2018.

The new signalling system being installed this weekend will act as a backup to the current system until the work has been completed on the entire line. The move is expected to eventually allow more trains to move more quickly along the system.

The work will cost between $400- and $800-million and is being funded by both the city and the province.

Ross said similar work will eventually have to be carried out to replace the ageing signalling system on the Bloor-Danforth Line, but that work is not yet funded.