EURO 2024 Copenhagen
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1677. Scheduling ULD loading operations in air cargo hubs

Invited abstract in session TD-60: Resource constrained scheduling, stream Project Management and Scheduling.

Tuesday, 14:30-16:00
Room: S09 (building: 101)

Authors (first author is the speaker)

1. Ricardo Euler
Network Optimization, Zuse Institute Berlin
2. Ralf Borndörfer
Optimization, Zuse-Institute Berlin
3. Christian Puchert
Ab Ovo Deutschland GmbH
4. Tuomo Takkula
APS, Ab Ovo Germany GmbH

Abstract

Air cargo typically moves through airports that serve as hubs. A container or pallet, usually referred to as a unit load device (ULD), arriving at such a hub often holds shipments bound for various destinations. Consequently, its contents must be unloaded and moved into storage (ULD break-down). Once enough shipments for a single destination have accumulated, a new outbound ULD is loaded (ULD build-up). Both the build-up and break-down procedures need to be executed on a limited number of workstations and within the strict timeframe dictated by the flight schedule. Resource conflicts, therefore, need to be prevented by a careful scheduling of build-up and break-down processes.

We explore the structure and challenges of these interdependent scheduling problems, both from a mathematical and industry viewpoint, and discuss appropriate solution strategies. We find that breakdown scheduling is easily solved by simple mixed-integer programming (MIP) models on realistic datasets. The situation differs for build-up scheduling, where a desire to build up ULDs in batches introduces an additional objective. Here, we discuss a tailored approach based on logic-based Benders decomposition that decomposes the time horizon based on cargo availability. Finally, we discuss how to integrate both break-down and build-up scheduling into a unified network design model.

Keywords

Status: accepted

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