Effect of block length and yard crane deployment systems on overall performance at a seaport container transshipment terminal

As more and more container terminals open up all over the world, terminal operators are discovering that they must increase quay crane work rates in order to remain competitive. In this paper we present a simulation study that shows how a terminal's long-run average quay crane rate depends on (1) the length of the storage blocks in the terminal's container yard and (2) the system that deploys yard cranes among blocks in the same zone. Several different block lengths and yard crane deployment systems are evaluated by a fully dynamic, discrete event simulation model that considers the detailed movement of individual containers passing through a vessel-to-vessel transshipment terminal over a several week period. Experiments consider four container terminal scenarios that are designed to reproduce the multi-objective, stochastic, real-time environment at a multiple-berth facility. Results indicate that a block length between 56 and 72 (20-ft) slots yields the highest quay crane work rate, and that a yard crane deployment system that restricts crane movement yields a higher quay crane work rate than a system that allows greater yard crane mobility. Interestingly, a block length of 56–72 slots is somewhat longer than the average block in use today. The experiments provide the first direct connection in the literature between block length and long-run performance at a seaport container terminal. The simulator can be suitably customized to real, pure-transshipment ports and adequately tuned to get an appreciable prescriptive power.