2000 vehicles are composed of one, two, or (in the case of rebuilt units) three sections, and in most cases operate in multiple. The tram network carries 202 million passengers trips per year, adding up to 368 million passenger-kilometres. Trolleybuses The city's tram routes are supported by 6 trolleybus routes, with a total route length of . As with the city's tram routes, most of the trolleybus routes run from suburb to suburb, although their penetration of the city centre is less complete than the trams. Like the tram network, the trolleybus network is electrified using overhead line at 600 V DC, and shares a common electrical supply infrastructure. Service is provided by 80 trolleybuses, which between them cover over 5 million vehicle-kilometres per year. All the city's trolleybuses are articulated buses, with 17 being extra-long double-articulated vehicles. All the double-articulated vehicles, along with a further 18 of the single-articulated units, are low floor. The trolleybus network carries 54 million passengers trips per year, adding up to 119 million passenger-kilometres. Motor buses The VBZ also operates 60 motor bus routes. The bus routes can be broken down into urban routes (18 routes), district routes (9 local minibus operated feeder routes within the city) and regional routes (33 routes in the region around the city). The VBZ operates 181 motor buses, of which 85 are standard buses, 73 are articulated buses and 23 are minibuses. With the exception of 8 articulated buses, all motor buses are low floor. VBZ buses on the urban routes cover just under 6 million vehicle-kilometres a year per year, with district routes adding a further 1 million vehicle-kilometres and regional routes contributing 2 million vehicle-kilometres. Additionally, much of the regional service is provided by contractors operating on behalf of the VBZ, with such services covering a further 4 million vehicle-kilometers per year. The urban motor bus network carries 37 million passengers trips per year, adding up to 75 million passenger-kilometres. The district bus network carries 2 million passengers trips per year, adding up to 3 million passenger-kilometres. The regional bus network carries 20 million passengers trips per year, adding up to 62 million passenger-kilometres. Funiculars and rack railways The VBZ operates two funiculars and one rack railway within the city of Zürich: The Rigiblick funicular, in the north-east of the city, connects a lower station served by tram and trolley bus routes with an upper station