The abbreviation AST in German means “Anruf-Sammel-Taxi”, in English “call-collective-taxi” and ALT means “Anruf-Linien-Taxi” – call-line-taxi. Both are demand-oriented special forms of public transport in urban, local or even regional traffic. With a small number of passengers, a large bus in regular service is uneconomical. That’s why there are the AST and ALT services – they are only in operation there is need and demand – “on-demand” in a manner of speaking.