There will be significant closures this weekend on both the TTC and GO Transit’s Lakeshore East line.

Until Monday the Lakeshore East line will be closed for routine track maintenance. For those coming from Durham, 90B GO buses will run in the meantime between Oshawa, Whitby, Ajax Pikering and the Union Station bus station.

“The work carried out this weekend will stretch across almost 50 kilometres,” Metrolinx said in a statement. “It includes upgrades that will add two decades onto the lifespan of a major bridge as well as signal upgrades and station improvements.”

On Saturday the TTC will close the Yonge-University subway line from St. Clair to Union station until 8 p.m.

On Sunday, the line will close again between Bloor-Yonge and Lawrence station, reopening on Monday morning.

All stations except Summerhill will remain open for bus and streetcar service. Shuttle buses will run by each of the stations impacted.

The closures will make way for the installation of the TTC’s automatic train control system, which allows trains to run and stop automatically, rather than manually.

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