Most cities that I know have one or more major downtown streets where parades and other major civic celebrations tend to occur. San Francisco's Market Street, Chicago's State Street (pictured), and New York's Fifth Avenue are obvious examples.
These same cities, if they value transit, often want this same street to be the core of their transit system, because they want transit to deliver customers to the "front door" of the city.
So it's normal to see huge, complex reroutings of transit service when one of the civic events is happening. The legibility problems of this shift are accepted because they happen only a few times a year.
Vancouver, however, does something different, and I want to verify how unusual it is. Vancouver's core downtown transit street, Granville Mall, is closed to buses (and all vehicles) every weekend evening. Specifically:
On Fridays, Saturdays, Sundays, Holidays and the day before a Holiday, buses will run along Granville each day until 9pm, then switch to the re-route, travelling northbound on Seymour and southbound on Howe. The re-routes will stay in place until the close of service.
So many of Vancouver's most important street-running transit lines (mostly trolley buses in this case) shift from one downtown street to another at 9pm on almost half of all days. So the process of explaining and remembering where to find the bus is complicated all the time, which is quite different from finding the street closed for a very rare parade.
What North American cities do this routinely with their main transit street? Nicollet Mall in Minneapolis is the only example that comes to my mind, but its role in the transit network is much less important than Granville's.
To be clear, I'm not interested in reopening the Granville Mall debate, where many advocated closing the street to buses entirely. I am interested in the precedent as it might apply to other important transit streets, in Vancouver or elsewhere.