On-demand transport
Public transport without a fixed route or timetable. Vehicles are booked and routed according to the requests that come in.
On-demand transport is public transport that has no fixed route or timetable. Passengers book a trip, and the route and departure are formed from the bookings. In German the family covers Bedarfsverkehr and On-Demand-Verkehre, and older forms such as Rufbus and Anrufsammeltaxi belong to it too.
It exists because fixed lines are efficient only where demand is concentrated in space and time. In rural areas, in the evenings, at weekends, and in dispersed settlement patterns, a scheduled bus either runs almost empty or does not run at all. Flexible service covers those gaps without committing to a line that cannot fill itself.
Two features change how it is planned. Stops can be virtual, meaning a location where a vehicle will stop on request without any physical infrastructure, which lets a service reach places no bus stop could justify. And booking channels decide who can actually use it: an app-only service excludes part of the population that most needs it, which is why phone booking usually stays. For analysis this matters because on-demand service is invisible to a stop-based accessibility calculation, so leaving it out understates what a region actually offers.