Fuzzy multi-objective reconstruction plan for post-earthquake road-network by genetic algorithm

Abstract

According to the seismic experience of Japan and America, earthquakes have often caused damage to the road-networks, which are important for maintaining the quality of life and the daily transit after a disaster. Taiwan and Japan are both located in the Pacific earthquake region, which is very active and unstable. The Taiwanese people will suffer seriously after a large-scale earthquake because the population and road-network are both highly concentrated nowadays. If the necessary reconstruction strategies to cope with quakes are not available, mass travelers can't be efficiently conducted via the post-earthquake road-network. Thus, the convenience of transit after earthquake would be seriously hampered. To aid the reconstruction decision for post-earthquake road-networks, we intend to establish a fuzzy multi-objective model, which is an integration of work scheduling and task assignment for many work-troops. Multiobjective optimization is applied because of the following reasons: first, we do want to minimize the travel-time of travelers during reconstruction; secondly, we intend to minimize total time needed for reconstruction; furthermore, we also expect that each available and homogeneous work-troop on duty will share almost the same work-load during reconstruction. Since the aspiration level of the aforementioned goals are vague, a fuzzy multi-objective approach is used. The algorithm of this combinatorial optimization problem based on a two-step genetic algorithm is then developed and employed to reduce the computation complexity of such a problem. Study results show that a satisfying solution of this problem can be efficiently derived by thirty generations of our modified genetic algorithm- this solution not only instructs the reconstruction order for each damage point in road-network, but also assign the appropriate reconstruction work to relevant work-troops. Thus, for reasons of computational efficiency and practical applicability in this study, we do strongly suggest this research can't only be a basis for seismic simulation but can also be the reference of pre-quake exercises for relevant authorities.