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Journal of Applied Mathematics
Volume 2014, Article ID 418689, 12 pages
http://dx.doi.org/10.1155/2014/418689
Research Article

Double Girder Bridge Crane with Double Cycling: Scheduling Strategy and Performance Evaluation

1School of Computer Science and Engineering, Southeast University, Nanjing 211189, China
2Key Laboratory of Computer Network and Information Integration, Ministry of Education, Nanjing 211189, China
3Department of Civil and Environmental Engineering, University of Washington, 121E More Hall, P.O. Box 352700, Seattle, WA 98195-2700, USA

Received 19 February 2014; Accepted 7 August 2014; Published 25 August 2014

Academic Editor: X. Zhang

Copyright © 2014 Dandan Wang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

This paper introduces a novel quay crane design, double girder bridge crane (DGBC). DGBC is capable of handling containers of two adjacent bays simultaneously, avoiding crane collisions, saving travelling and reposition cost, and eventually improving terminal efficiency. This problem is formulated as a resource-constrained project scheduling with objective to minimize the maximum completion time. A two-stage heuristic algorithm is proposed in which an operating sequences on each bay is obtained by double cycling, and the integrated timetable for both bays is constructed by solving resource conflicts using the proposed minimum cost strategy. We examine effectiveness and performance of applying DGBC with double cycling. A case study is presented to illustrate how DGBC works with the two-stage method. Three extreme cases with respective conflict types are investigated to develop the performance bounds of DGBC with double cycling. The results show that DGBC can significantly improve terminal productivity, and outperforms single girder crane in both makespan and the lift operation percentage. The highest DGBC efficiency does not require maximum double cycles in two bay schedules; rather the integrated timetable for two bays is the main contribution to the DGBC performance as it yields better cooperation between two spreaders and the driver.