at Rigiblick on the Zürichberg hill. It is both owned and operated by the VBZ. The Polybahn funicular, in the centre of the city, links the city centre with the university. It is operated by the VBZ on behalf of its owners, the banking group UBS AG. The Dolderbahn rack railway, in Zürich's eastern suburbs, connects a lower station served by trams with an upper station adjacent to the Dolder Grand Hotel. It is operated by the VBZ on behalf of its owners, the Dolderbahn-Betriebs AG. Tariffs and tickets All services operated by the VBZ operate on a proof-of-payment system. Passengers are required to purchase a ticket before boarding any vehicle. Passengers may board through any door and are not required to show tickets on boarding. Tickets may be purchased from machines found at all of the VBZ's tram stops, and many bus stops. At bus stops without ticket machines, passengers without tickets must board through the front door and purchase a ticket from the driver. Ticket checks are randomly carried out by roving teams of fare inspectors, and penalties are imposed on passengers found without a valid ticket. VBZ's passenger services are operated within the tariff and ticketing system provided by the cantonal public transport authority Zürcher Verkehrsverbund (ZVV). This system covers the whole of the canton of Zürich and thus covers travel on services provided by many other operators, and includes the Zürich S-Bahn suburban rail network. Free transfer is permitted between different vehicles, routes, modes and operators, provided a ticket valid for the whole journey is held. The ZVV system is zonal in nature, with fares for individual journeys set by the zones the journey passes through. Not all zones are equal, with higher fares being charged for travel in some zones. The whole of the city of Zürich is within a single zone, but as some VBZ routes travel beyond the city boundaries, a multi-zone ticket is needed for some VBZ journeys. Both single journey and day tickets are available, as are a number of passes with longer validities. Other activities Besides its passenger transport activities, VBZ, jointly with the city refuse and recycling department ERZ, operates the cargo tram to collect bulky waste. The cargo tram serves 9 different collection points around Zürich, calling at each on different days of the month. The collected refuse is taken to a specially constructed siding at the ERZ