Road closures across the city complicate travel in the GTA this weekend, adding to issues caused by a continuing downpour and slippery driving conditions.

Closures from two marathons, the Global Marijuana March, a Khalsa Day parade and spring maintenance will affect areas of the downtown, North York, Etobicoke and Mississauga.

For those looking to avoid traffic snags via public transit, there are two major TTC service changes to be aware of.

Line 3 of the subway will be closed for track work Saturday and Sunday. Also beginning Sunday, the TTC is replacing its Queen streetcars with buses for the next four months.

All weekend

Allen Rd. will be closed for maintenance between Sheppard and Eglinton Aves. from 11 p.m. Friday to 5 a.m. Sunday, the City of Toronto said. Motorists are encouraged to use Dufferin and Bathurst Sts. instead, and to expect delays, although the city has made timing changes to traffic signals nearby to account for congestion.

The rainy weather means some sewer work and Toronto Hydro inspections may not go ahead, but the city says other fixes — such as bridge maintenance, streetlight inspections, catch-basin cleanings, line repainting and guiderail repairs, among other things — will be completed as planned.

Other closures will be caused by the Mississauga Marathon, which has races both Saturday and Sunday.

Saturday’s races start in Port Credit at 6 p.m. and Clarkson at 6:30 p.m., with both the 10K and 5K routes winding along the waterfront to Cumberland Dr., eventually finishing at Lakefront Promenade Park. A full list of closures and times can be found on the marathon website.

On Sunday, races start at 7:30 a.m. at Celebration Square near Square One Mall and 12:30 p.m. at Hiawatha Park.

The main closures will be along Burhmanthorpe Rd., Mississauga Rd., Indian Rd. and the lakeshore. For a full list, check the marathon website.

Saturday

From noon to 4:30 p.m., 5,000 people are expected to participate in the Global Marijuana March in downtown Toronto. Starting at 1:30 p.m., the crowd is expected to begin in North Queen’s Park and walk north along Queen’s Park Cres., east on Bloor St. E, south on Yonge St., west on Wellesley St. and back north along Queen’s Park Cres.

Certain TTC routes, including the 94 Wellesley and 5 Avenue Rd. buses, will be diverting around the march. A full list of exact closures and times is available on the Toronto police website.

Sunday

More closures downtown will be caused by the Goodlife Fitness Toronto Marathon, which is going ahead despite soggy weather conditions.

Race routes start in North York’s Mel Lastman Square, north of Yonge St. and Sheppard Ave., on Lake Shore Blvd. near Strachan Ave. and on Rosedale Valley Rd. near Alymer Ave.

Various races will run along Yonge St., Bayview Ave., King St. E, Wellington St. E, Front St. E and Lake Shore Blvd. The earliest closures begin at 5:30 a.m., with the latest stretching until 4 p.m.

A full list of what will be closed with exact times is posted on the Toronto police website. TTC routes will be running through gaps in the run where possible and when safe, police said.

The Sikh Spiritual Centre’s Khalsa Day Parade will also be running Sunday, causing some road closures between 1 p.m. and 10 p.m.

The parade route will begin at Airport Rd. and Morning Star Dr., running along Morning Star Dr. until it enters Toronto at around 2:45 p.m. Then, it’ll turn north along north on Humberwood Blvd. and Humberline Dr., east on Finch Ave. W, north on Westmore Dr. and west onto Carrier Dr.

The TTC will experience delays. A full list of closures and times is on the Toronto police website.