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Upcoming events:


Workforce Management in Delivery Operations
(ProLog/ PLIS Colloquium)

       by Maciek Nowak (Quinlan School of Business)

 

Date:           29th May 2017 - Time: 13:30

Location:      Hörsaal 12
                   Faculty of Business, Economics and Statistics
                   (Oskar-Morgenstern-Platz 1, 1090 Vienna)

Abstract:
Service quality and driver efficiency in the delivery industry may be enhanced by in-creasing the regularity with which a driver visits the same set of customers. However, effectively managing a workforce of drivers may increase travel distance, a traditional metric of the vehicle routing problem (VRP). This research evaluates the effect that workforce management has on routing costs, providing insight for managerial decision making. The analysis is presented in the context of the period vehicle rout-ing problem (PVRP), an extension of the VRP with vehicle routes constructed to ser-vice customers according to preset visit frequencies over an established period of time. We develop models to apply workforce management principles. Through a computational study with standard PVRP test cases and real-world delivery data, we show that multi-objective PVRP models can achieve a balance between workforce management and travel distance goals. With the proper parameters in place, work-force management principles may be successfully applied without sacrificing other operational objectives.


Exact Methods for Non-Hamiltonian Routing Problems (ISOR Colloquium)
       by Hande Yaman (Bilkent Univ.)

 

Date:           29th May 2017 - Time: 16:45 - 17:45

Location:      Hörsaal 7
                   Faculty of Business, Economics and Statistics
                   (Oskar-Morgenstern-Platz 1, 1090 Vienna)

Abstract:
The classical traveling salesman problem (TSP) seeks a Hamitonian cycle (a cycle that visits every node exactly once) of minimum cost. Even though early routing problems focus on finding Hamiltonian cycles, many routing applications also require the choice of nodes that are to be visited or the number of times a node is visited. In this talk, we present exact methods for three non-Hamiltonian routing problems; namely, the split delivery VRP, the time constrained maximal covering TSP and the VRP with roaming delivery locations. We propose an iterative approach to solve the split delivery VRP where a relaxation is tigthened at each iteration by adding new variables and constraints. For the time constrained maximal covering TSP, we give a new family of facet defining inequalities and use them in a branch-and-cut approach. Finally, we present a branch-and-price algorithm to solve the VRP with roaming delivery locations. This is joint work with O.E. Karasan, M. Savelsbergh and G. Ozbaygin.

Faculty of Business, Economics and Statistics
University of Vienna
Oskar-Morgenstern-Platz 1
A-1090 Vienna


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