Achieving Full Plan Multimodality by Integrating Multiple Incomplete Journey Planners

Although in principle, providing a fully multimodal journey planner supporting the planning with all types of transport services and their combinations is now algorithmically possible, providing such fully multimodal journey planning in practice remains elusive. This situation is largely caused by the fact a fully multimodal journey planner requires a wealth of detailed data about all transport services and these are often difficult and/or costly to obtain. In this paper, we present a novel, elegant approach to overcome this problem. Our approach is based on journey planner integration -- it obtains a fully multimodal journey planning capability by interconnecting, in a smart way, multiple incomplete journey planners, each with only limited modal and/or geographical coverage. The integration relies on a planning metagraph, a simplified representation of the underlying transport system which can be build with only a minimum amount of data. We have successfully tested our approach in real-world conditions of the greater metropolitan area of Barcelona, confirming the feasibility of our approach to achieve high-quality fully multimodal plans with a reasonable response time.