Flow-Based Guidebook Routing

Public-transportation route-planning systems typically work as follows. The user specifies a source and a target location, as well as a departure time. The system then returns one or more optimal trips at or after that departure time. In this paper, we consider guidebook routing, where the goal is to provide timeindependent answers that are valid over long periods of time. An example answer could be: Take Bus 10 to the main station, from there take Tram 11 or 13 (whichever comes next) to your target station. Trip duration: 30 minutes. Frequency: every 20 minutes. Valid: weekdays from 6am 8pm. We show how to compute such guidebook routes efficiently and with provably good quality. An evaluation on real-world data shows that few guidebook routes usually suffice for good coverage. We also show how guidebook routing can be used to speed up transfer patterns, a state-of-the-art method for public transportation routing.