The loader problem: Formulation, complexity and algorithms

G. Tang, F. Chen, Edwin Tai Chiu Cheng, Chi To Ng, Z. L. Chen

Research output: Journal article publicationJournal articleAcademic researchpeer-review


In this paper we consider a new transportation model, called the loader problem, which is frequently encountered by third-party logistics service providers in practice. It is a tactical staff-planning problem with the objective of minimizing the total labour cost of staffing a sufficient number of loaders on a given fleet of trucks that serve a given set of customer sites. We formulate the problem as an integer program and show that it is strongly NP-hard. We then consider two special cases of the loader problem that occur in certain practical situations, and propose polynomial and pseudo-polynomial time algorithms for solving these cases. We also propose a linear programming relaxation-based random rounding algorithm for the general problem and report the computational results of the algorithm.
Original languageEnglish
Pages (from-to)840-848
Number of pages9
JournalJournal of the Operational Research Society
Issue number5
Publication statusPublished - 1 May 2010


  • Algorithms
  • Integer programming
  • Loader problem
  • Logistics
  • NP-hard

ASJC Scopus subject areas

  • Management Information Systems
  • Strategy and Management
  • Management Science and Operations Research
  • Marketing


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