Effective ready mixed concrete supply adjustments with inoperative mixers under stochastic travel times

Abstract

The purpose of this study is to develop a systematic scheduling model that will help ready mixed concrete (RMC) carriers/suppliers with effective scheduling adjustment after temporary breakdown of mixers under stochastic travel times. The model is formulated as a mixed integer network flow problem with side constraints that is characterized as NP-hard. The authors employ problem decomposition and relaxation techniques, with a mathematical programing solver, to develop an algorithm that is capable of efficiently solving the problem. A simulation-based evaluation method is also proposed to evaluate the model, joined with a deterministic model, as well as the method currently used in actual operations. Finally, a case study is performed using real operating data from a Taiwan RMC firm. The preliminary results demonstrate that the stochastic model and the solution algorithm could be useful to reduce system cost for the RMC carrier in actual operations.

Keywords:

• Ready mixed concrete
• Stochastic travel times
• Truck dispatching
• Network flow

Acknowledgments

We would like to thank the ready mixed concrete firm for kindly providing the test data and their valuable opinions. We also thank the two reviewers for their helpful comments and suggestions to improve the presentation of the paper.