A mass transit pupil transportation bus shall be equipped with a system of mirrors that gives the seated driver a view of the roadway to each side of the bus and the area immediately in front of the front bumper, so that when a rod 30 inches long is placed upright on the ground at a point along a traverse line 1 foot forward of the forwardmost point of the bus and extending the width of the bus, at least 7-1/2 inches of the length of the rod shall be visible to the driver either by direct view or by means of an indirect visibility system.
67 Pa. Code § 171.135