Monorails, heritage tramways, miniature railways and funiculars also exist in several places. Carris operates Lisbon's buses, trams, and funiculars. Famous funiculars are among others the Hungerburgbahn in Innsbruck and the Mendel funicular in Kaltern. The Monte San Salvatore funicular is one of three operational funiculars within the Lugano area. The Akbil ticket is valid on all metros, trams, funiculars, ferry boats and buses. Poma has built numerous funiculars which are cable driven railways that can climb steep pitches. Sometimes passenger elevators are used as a city transport along with funiculars. The funiculars range from short urban lines to significant multi-section mountain railways. Cable cars are distinct from funiculars, where the cars are permanently attached to the cable. The line was at the time one of the lengthiest funiculars in Europe. The line opened in 1888, and is one of the few funiculars with water propulsion. Its track makes it one of the shortest public-transport funiculars in the world. Some of funiculars of this type were converted later on to electrical power.