Incremental search based multi-modal journey planning

A system, comprising:

• a processor-based journey planning incremental searcher for incrementally solving a current journey planning request from a user, wherein said journey planning incremental searcher incremental solves the journey planning request from the user by:
• incrementally solving a current journey planning request from a user, wherein said solving step includes:
• performing a current search for at least one journey plan that satisfies the current journey planning request by accessing a database storing journey planning information derived from results to a plurality of previous journey planning requests;
• storing, in the database, at least part of the information discovered during the current search for responding to a subsequent journey planning request;
• and
• providing, on a display device, the at least one journey plan to the user,
• wherein the at least part of the information discovered during the current search for responding to the subsequent journey planning request includes a reusable portion of a search graph, pairs of a state and a lower bound on a best arrival time and pairs of a state and an exact value for the arrival time, the lower bound employed to increase an accuracy of a pre-computer heuristic function which guides the search based on state dominance in one or more search spaces in which heuristic values are back propagated and stored in the database.