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The heterogeneous fleet vehicle routing problem is investigated using some adaptations of the variable neighborhood search (VNS). The initial solution is obtained by Dijkstra's algorithm based on a cost network constructed by the sweep algorithm and the 2-opt. Our VNS algorithm uses several neighborhoods which are adapted for this problem. In addition, a number of local search methods together with a diversification procedure are used. Two VNS variants, which differ in the order the diversification and Dijkstra's algorithm are used, are implemented. Both variants appear to be competitive and produce new best results when tested on the data sets from the literature. We also constructed larger data sets for which benchmarking results are provided for future comparison.

SUMMARYThe vehicle routing problem with back-hauls involves the design of a set of minimum cost routes, originating and terminating at a central depot, for a set of vehicles to service a set of customers with known quantities to be either delivered or collected. This paper describes two route-construction heuristics that generate initial solutions quickly. These heuristics are based on the saving-insertion and saving-assignment procedures, respectively. The initial solutions are then improved by a reactive tabu search meta-heuristic. The reactive concept is used in a new way to trigger the switch between di erent neighbourhood structures for the intensiÿcation and diversiÿcation phases of the search. Special data structures are also used to manage e ciently the search of the neighbourhood space. Computational results are reported for a number of benchmarks. The results show that the proposed meta-heuristic is robust and competitive to the best approaches in the literature.

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Purpose -Most collaborative SCM research has focused on the ideal situation of a manufacturer engaging with all its downstream partners. In view of extensive entry costs, lack of trust or simply non-suitability of electronic data processing systems this, however, provides only limited support to actual problems of many companies. The paper seeks to investigate various common supply chain performance measures to show what impact increasing adoption of collaborative replenishment between manufacturer and several major customers has on each market participant. Design/methodology/approach -The study uses discrete event simulation to evaluate various adjustments within the distribution frameworks of two food-manufacturers and their major customers. Findings -The analysis suggests that manufacturer and customers can substantially benefit from even a partial increase in demand visibility. This nevertheless can be costly since favouring some customers due to sharing a collaborative replenishment system, while others often seem to experience heavier delivery delays and declining service-level.Research limitations/implications -The research focused on the delivery framework of the two involved manufacturers and the chosen products. Hence, research findings may differ and need to be modified before drawing conclusions for different products, companies or industries. Practical implications -The analysis aims to help practitioners to identify possible opportunities and threats within an expanding collaborative SC replenishment system. Originality/value -Investigating heterogeneous delivery frameworks within an emerging collaboration system has not been addressed much within prior SCM research. It aims to help mainly small-or medium-sized enterprises to reveal possible advantages and drawbacks within the process of emerging with a varying number of customers from a traditional predetermined reorder-point into a collaborative VMI/CPFR system.