What type of mirror is required on the outside of a bus?

The requirement for an exterior crossover convex mirror on the outside of a bus is based on safety and visibility considerations. This type of mirror is designed to provide a wider field of vision, allowing the driver to detect pedestrians, cyclists, and other vehicles that might be in proximity to the bus, especially in blind spots. The convex shape of the mirror helps expand the area that can be seen, thereby reducing the risk of accidents during maneuvers such as turning or changing lanes.

In contrast, other mirror types may not offer the same level of visibility enhancement or are not specifically mandated for bus safety. A sideview mirror typically provides a direct view of adjacent lanes but might not adequately address blind spots. A rectangular flat mirror would offer a more accurate representation of distance but lacks the wide-angle advantage needed for larger vehicles like buses. A convex side mirror might assist with visibility to some extent, but the crossover convex design is specifically tailored for the unique safety needs of buses, making it the preferred and required choice for this application.