This paper proposes a multiagent-based route optimization method as a next-generation transportation system to generate a sustainable route network which can transport stranded persons effectively even if the road conditions are changed in a disaster situation. For this purpose, we apply a multiagent approach into the route optimization method where an agent corresponds to one route. Such an approach is very useful in a disaster situation because it is easy to add/delete routes and modify their routes according to the dynamic condition change and constraints. Towards a sustainable route network by multiagent approach, our route optimization method (1) employs the bus stop clustering method to generate clustered routes, (2) introduces a cluster-extension method to connect routes in different clusters and (3) adopts the evaluation function in consideration of damage by a change in the condition of roads. Intensive simulations on Mandl's urban transport benchmark problem have revealed the following implications: (1) the proposed method has succeeded in reducing stranded persons, detour persons, detour time, all of which are caused by road condition changes; (2) detour routes have emerged, which contribute to an increasing network sustainability; and (3) we have succeeded in reducing both the passenger's transportation time and the number of buses in a non-damaged situation.

Abstract. This paper focuses on the passenger traffic bottlenecks occurred in the bus route network in disaster situations and proposes the multi-agent based bus route optimization method to resolve such bottlenecks by generating the networks which can effectively transport many stranded persons including ones who wait around the station as the passenger traffic bottlenecks. For this purpose, the proposed method modifies the bus route networks generated as usual conditions to suitably pass many bus lines to and redistribute the buses among the bus lines according to the number of passengers. The intensive simulations have revealed the following implications: (1) the proposed bus route network optimization method generates the route network which is suitable for passenger traffic bottlenecks; (2) the proposed method decreases a risk of the bottlenecks; and (3) our method transports the passengers faster than those by the conventional one in various virtual disaster situations.

To optimize the problem composed of (i) the common components which should be optimized from the viewpoint of all objective functions and (ii) the special components which should be optimized from the viewpoint of one of the objective functions, this paper proposes a new multi-objective optimization method which optimizes not only the common components for all objective functions but also the special ones for each objective function. To investigate the effectiveness of the proposed method, this paper tested our method on the test-bed problem which is an extended version of the 0/1 knapsack problem. The intensive experiments have revealed the following implications: (i) Our method finds better solutions which have higher fitness than the conventional method (NSGA-II); (ii) our method can find the solutions that had a large norm (which corresponds to a high profit of an airline company in the flight scheduling problem) with the high rate of the common components; and (iii) since the crowding distance employed in our method contributes to keeping the diversity during the solution search, our method has high exploration capability of solutions.