The driver of a Boston Public Schools bus that collided with an MBTA bus early this morning has been hospitalized, a schools spokesman said.The collision occurred at Washington Street and Columbus Avenue in Roxbury at 5:43 a.m.Transit police said there were no children on the school bus. Five passengers on the Route 44 T bus reported minor injuries.T police said their preliminary investigation suggests the school bus driver was at fault, That driver was transported to an area hospital, according to BPS spokesman Daniel O'Brien.