“…To overcome this difficulty and to make the analysis simpler, existing studies typically use 'sequential' modeling approach, which assumes sequential operations of different resources that can work at least partly simultaneous. For example, Yang, Choi, and Ha (2004) , Roy and De Koster (2014) , Dhingra, Roy, and De Koster (2017) , Roy et al (2015) , and Gupta et al (2017) assume sequential operations of quay/stack cranes and AGVs while modeling the seaside operations at an automated container terminals with AGVs. They assume that the quay crane's container retrieval process can only start after an empty AGV arrives at the quayside.…”