A transit service which operates on only a portion of a route. Regularly scheduled mass transportation service which is open to the public, designed or modified to accommodate the needs of school students and personnel which uses various fare collection or subsidy systems. Buses used in tripper service must be clearly marked as open to the public and may not carry designations such as "school bus" or "school special." These buses may stop only at regular bus stops. All routes traveled by tripper buses must be within the regular service areas as indicated in published schedules. School tripper service should operate and look like all other regular service.