Efficient multi-request route planning on road network

Given a source node, a destination node and a request list, the result of the requirement-oriented route planning is a path which has minimum distance/travel time/money and could satisfy all the requests at the same time. Most of the previous studies supposed that each Point-Of-Interest (POI) provides only one type of service, which is known as the trip planning query (TPQ). The problem is more complicated if each POI provides multiple services, which is called multi-request route planning (MRRP) problem. The existing MRRP method is designed based on A∗ algorithm in the POI network. However, they need a huge amount of calculations to get the heuristic values based on the detour distances, which is inefficient especially for large scale road networks. Moreover, it doesn't pay attention to the request on the list which is hard to satisfy. If some required service can be provided only by one node, this node should be regarded as a key point, who will definitely be visited. Based on the above observation, we propose a new framework to solve the MRRP problem, which takes the overall distribution of the POIs who provide the required services into account. Furthermore, we design two algorithms GOD and SPGOD using the framework with the help of a grid index. They can identify the POIs that will definitely be visited earlier, and guide the expansion towards such POIs which can further improve the effectiveness and efficiency. Extensive experiments have been conducted to evaluate and compare the performance of the proposed algorithms and the existing algorithm.