It's going to be quite the nightmare getting around Toronto using public transit this weekend, with a series of overlapping TTC and GO Transit outages threatening chaotic conditions in the city.

Metrolinx has announced that trains will be replaced with buses due to construction and maintenance work along the Lakeshore East and Stouffville GO Lines, while the TTC will be shutting down service on a stretch of Line 1.

Commuters relying on the GO Lakeshore East Line will have to manage with replacement buses starting Friday evening and through the entire weekend. Meanwhile, Stouffville Line trains will be replaced by buses on Saturday and Sunday.

Metrolinx warns that "Buses do not have the same capacity as trains, so customers may wish to see what other GO Transit bus options are available, including some that connect to the TTC."

The GO Line closures are to accommodate early works for the Ontario Line subway project, along with GO expansion and maintenance.

Local commuters will also suffer the indignity of shuttle buses, as the TTC will be shutting down subway service on Line 1 between Finch and St Clair stations on Saturday and Sunday.

The full Line 1 will also close early at 1:30 a.m. on Saturday, with both closures to accommodate commissioning of the new Automatic Train Control system serving the route.

A portion of Line 2 will also be out of commission for a portion of the weekend, with a late opening planned Sunday between St. George and Broadview stations, due to beam replacement work on the Prince Edward Viaduct, resuming by noon.

The closures coincide with several weekend festivals, concerts, markets, and other events all but certain to result in packed TTC and GO shuttle buses.