The Toronto Transit Commission has fired two senior executives in charge of the over-budget and delayed Toronto-York Spadina subway extension.

In a memo released Thursday afternoon, TTC CEO Andy Byford said the two managers have been let go.

The 8.6-kilometre extension is reportedly $400 million over the $2.6-billion estimated cost and was originally supposed to be completed this year, but is now expected to be open in 2017.

Byford is expected to update the public on the extension’s new construction timeline on Friday.

Following Thursday's announcement, Mayor John Tory said he supports Byford's decision to shake-up management.

"During the election campaign and since taking office, I've been clear about the need for much stronger culture of accountability at City Hall, specifically in the management of major public infrastructure projects," Tory said in a statement.

"TTC CEO Andy Byford has my full support in his efforts to restore public confidence in the management of the Toronto-York Spadina subway extension. Torontonians have a right to expect better."