The R4 41st Ave (designated the 91 B-Line during planning stages) is an express bus route with bus rapid transit elements in Metro Vancouver, British Columbia, Canada. Part of TransLink's RapidBus network, it replaced the 43 Express that travelled along 41st Avenue, a major east–west route that connects the University of British Columbia (UBC) to the SkyTrain system's Oakridge–41st Avenue station on the Canada Line and Joyce–Collingwood station on the Expo Line.