More than 25,000 runners from 70 countries will participate in a marathon snaking through downtown Toronto, resulting in a number of road and transit closures for commuters this weekend.

The 2018 Scotiabank Toronto Waterfront Marathon is scheduled to take place on Sunday, but some roads will be closed as of 11 a.m. on Saturday in preparation for the event.

These are the roads closed from 11 a.m. on Oct. 20 to 8 p.m. on Oct. 21:

- Bay Street from Queen Street West to Dundas Street West. Motorists wishing to access hotels and parking garages can do so from Dundas Street West.

- Hagerman Street from Bay Street to Elizabeth Street

- Elizabeth Street from Hagerman Street to Dundas Street West

- Albert Street from Bay Street to James Street

- James Street from Queen Street West to Albert Street

The following roads will be closed on Oct. 21:

4 a.m. to 11 p.m.:

- University Avenue from Dundas Street West to King Street West

- Armoury Street from Centre Avenue to Chestnut Street

- Bay Street from Queen Street to Lake Shore Boulevard

- Queen Street from University Avenue to Yonge Street

5 a.m. - 1 p.m.:

- Lake Shore Boulevard from Windermere Avenue to Bathurst Street

6 a.m. - 1 p.m.:

- Lake Shore Boulevard from Bathurst Street to Don Roadway

- Harbour Street from York Street to Bay Street

- Bay Street from Lake Shore Blvd to Queens Quay

- Exceptions include the following locations:

- Eastbound curb lane on Lake Shore Boulevard West from Windermere Avenue to Oarsman Drive to allow access to the Boulevard Club, Royal Canadian Legion

- Access to HMCS York, Coronation Park, and Ontario Place shall be provided from Stadium Road

- Jameson Road eastbound off-ramp is scheduled to reopen at 11 a.m. for access to Exhibition Place

6 a.m. - 3:30 p.m.:

- Front Street Eastbound lanes only from York Street to Jarvis Street

- Wellington Street from Church Street to Bay Street

- Church Street from Simcoe Street to Yonge Street

- Richmond Street from Simcoe Street to Yonge Street

- Adelaide Street from Simcoe Street to Yonge Street

7 a.m. - 1:30 p.m.:

- Queens Quay West from Bay Street to Parliament Street

- Cherry Street from Lake Shore Boulevard to Mill Street

- Mills Street from Cherry Street to Bayview Avenue

- Bayview Avenue from Mill Street to River Street

8 a.m. - 11 a.m.:

- University Avenue / Queens Park Crescent from Dundas Street to Bloor Street

- Bloor Street from Queens Park Crescent / Avenue Road to Bathurst Street

- Bathurst Street from Bloor Street to Lake Shore Boulevard

- Fort York Boulevard from Bathurst Street to Lake Shore Boulevard

8 a.m. - 3:30 p.m.:

- Lake Shore Boulevard East from Carlaw Avenue to Coxwell Avenue westbound lanes only

- Lake Shore Boulevard East full closure from Coxwell Avenue to Woodbine Avenue

- Queen Street from Woodbine Avenue to Beech Avenue

- Eastern Avenue / Front Street from Carlaw Avenue to Jarvis Street

There are a number of GO Transit closures due to the marathon and construction work scheduled across the network.

All trips along the Lakeshore West and East lines are expected to take 15 minutes longer than scheduled.

Lakeshore West trains will not be stopping at Mimico or Exhibition GO Stations. There will be a train making special trips to Exhibition station from Union Station.