The driver may not permit the transportation of any article within the body of the motor bus that would interfere with passengers or with the safe operation of the motor bus. The driver may not permit any article to obstruct the aisle, stepwell or steps. This section does not apply to a dog trained to lead blind or deaf persons or to provide support for mobility-impaired persons under s. 106.52(3) (am), Stats.
Wis. Admin. Code Department of Transportation Trans 330.05