Yes, whenever they have marathons or bike races in Toronto they close the highway into downtown and a bunch of streets. It's pretty awful to get anywhere. I don't know why they don't just hold it along the lakeshore. 

Whenever big races like these take place, many roads gets closed. The most awesome road closure I've ever experienced was when I ran the half marathon in the Rock n Roll Marathon series in Seattle. They friggin' closed all the south bound lanes on a large section of I5 near downtown Seattle. It was pretty wild, and awesome at the same time, to run in the middle of a very wide very busy section of an interstate highway.