Eglinton Avenue (if I remember correctly) is Toronto's longest east-west street. I've been there multiple times and Eglinton has a horde of bus lines and both Eglinton subway stations are packed during rush hour.
Enter the Eglinton/Scarborough LRT (15.5 miles) that somewhat shadows their current east-west Bloor-Danforth HRT subway. The plan is to construct this and connect it with their current Scarborough LRT. Scheduled to open in eight years.