No certificate of public convenience and necessity shall be granted to an applicant proposing to operate over the route of any certificated common carrier unless it is proved to the satisfaction of the Department that the service rendered by such certificate holder, over such route, is inadequate to the requirements of the public necessity and convenience; and if the Department is of the opinion that the service rendered by such certificate holder over such route is in any respect inadequate to the requirements of the public necessity and convenience, such certificate holder shall be given reasonable time and opportunity to remedy such inadequacy before any certificate shall be granted to an applicant proposing to operate over such route. For the purpose of this section, the transportation of passengers by an urban-suburban bus line, hereby defined as a bus line, the majority of whose passengers use the buses for traveling a distance no more than forty miles, measured one way, on the same day, between their places of abode and their places of work, shopping areas, or schools, shall not be deemed an operation over the route of any common carrier of passengers holding a certificate of public convenience and necessity.