Developing, Evaluating, and Comparing Multiple Parcel Delivery Networks Using Agent-Based Simulation
Type of DegreePhD Dissertation
Industrial and Systems Engineering
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This dissertation focuses on assessing and developing multi-tier hub-and-spoke parcel delivery networks. The multi-tier concept has been developed to enhance network performance by reducing delivery time and operational cost while increasing client satisfaction under the pressure of e-commerce growth. In this dissertation, we examine different multi-tier parcel delivery networks: the two- and four-tier, and hybrid networks. The two-tier network simulates one of the traditional hub-and-spoke parcel delivery networks. The four-tier was proposed to substitute traditional delivery networks by introducing new concepts, techniques, and changing the network layout and structure. The hybrid network is proposed in this dissertation to combine the two- and four-tier networks to improve the network performance. Our objective is to develop, evaluate, enhance, and compare multi-tier parcel delivery networks. Due to the current massive demand, maintaining high service levels is difficult. Challenges such as providing fast, reliable, and low-rate services force logistics service providers to change their mindset about the fundamental concepts of parcel delivery service to escalate their success. In doing so, we leverage concepts of the Physical Internet to develop the four-tier network and implement the containerization technique. This work has four studies and was shaped by a multi-year, multi-university research project for one of the largest international parcel delivery carriers. The first study investigates the evaluation and comparison between two- and four-tier networks under traditional operations such as bagging of small parcels. Findings show that the two-tier network is superior to the four-tier network except for average driving time per leg. Operational cost analysis shows that four-tier networks have an average 25% increase in cost compared to two-tier netwroks due to the increased number of scans. Additionally, average driving time per leg was reduced from about eight hours for the two-tier to about four hours for the four-tier. Implementation of the containerization technique and comparing the performance of the two- and four-tier networks when using containers instead of bags is our second study. Results indicate that containerization is one of the crucial techniques to be implemented to enhance parcel delivery network performance. Moreover, the percentage of late parcels is affected by using containers and is lowered by around 55%. The operational cost analysis shows that using containers reduces the operational cost when increasing the maximum container fill level. Another study proposed and assessed a new hybrid parcel delivery network. The proposed hybrid network, which combines two- and four-tier networks, has better results compared to the four-tier network when managers' priorities are lateness, operational cost, or driving time per leg. Results show that the multi-tier parcel delivery network has a huge potential for improvement. The last study investigates the effect of changing container capacities and types. Findings indicate that the selection decision of capacities and types has a major effect on operational cost. Besides, increasing the number of container types to a certain threshold enhances network performance. Exceeding that threshold does not affect the performance, but it could increase loading time of containers into trucks due to the need to stack them in a way that increases trailer utilization.