【正文】 n models. In order to do so, we started from one of the current stateof the art fully automated facilities, and added latest improvements to the model to see whether we could increase the performance to levels that we do not experience in practice (yet). We used TBA‘s own proven container terminal simulation suite TimeSquare to quantify the effects of each adjustment individually. In this article we describe this stepwise improvement approach from an imaginary existing terminal with Dual RMGs and AGVs, as would have been constructed in the 1990s. For each step towards a stateoftheart terminal with TwinRMGs and LiftAGVs we show the effect on productivity of the various involved equipment types. Starting scenario: a Year 2020 automated terminal Our starting terminal is a fictitious terminal with 16 double trolley quay cranes (backreach interchange, with platform between the legs) on a 1,500m quay. The yard consists of 35 stack modules with dual crossover (or nested) RMGs. Crossover RMGs are stacking cranes that can pass each other (one is smaller and can pass the larger one underneath). Because of the passing ability, both RMGs are able to serve both the waterside and the landside transfer area in the perpendicular stack layout. Waterside transport is done by lifton liftoff (LOLO) Automated Guided Vehicles (AGVs), which are pooled over all quay cranes. All modeled equipment has technical specifications as is appropriate for 10yearold equipment. The terminal is suitable for a yearly throughput of million TEU (TEU factor )。 they are pooled over all QCs). We will see how the bx/hr can be improved by implementing several changes. Step 1 – improvement 1: replacing dual RMGs by Twin RMGs The first step in which dual RMGs are replaced by Twin RMGs consists of a couple of related adjustments as well. We summarize the different adjustments and describe their expected influence on the terminal productivity: Use Twin RMGs instead of crossover RMGs: twin RMGs are identical RMGs that cannot pass each other. As a result they can only serve one side of the stack (under typical yard layouts, either landside or waterside). This reduces flexibility and can have a negative impact on productivity. On the other hand, those RMGs are slightly faster than the ones in the standard scenario ( m/s instead of m/s gantry speed). The yard layout is adjusted: ? There is no need for two pairs of rail to support a large and a small RMG。 it will be increased later. Results As shown in Figure 2, our simulations show an overall productivity increase in quay crane performance of to bx/hr (+ bx/hr at 5 AGVs per QC, equals +4%). This is the bined result of having more and faster RMGs in the terminal against having less flexibility in job assignment. The highest impact can be seen on the landside. With dual RMGs we had a two RMGs per stack module that could work on the waterside, but because of their limited speed, both actually needed to work on the waterside to achieve acceptable performances. This had a negative impact on the landside with long service times: over 10 minutes service time, meaning trucks had to wait at the RMG transfer zone for more than 10 minutes before their container was processed, on average! The truck service times drastically decrease when we use twinRMGs, with one RMG dedicated to the landside. Trucks are processed six minutes faster in the ?Improvement 1‘ scenario with twin RMGs, as shown in Figure 3. Step 2: increasing terminal throughput In Step 1 we mentioned a 19% increase in storage capacity because of the fact that more stackmodules with twinRMGs fit in the same space as stackmodules with dualRMGs. In this step we also increase maximum stacking height from four to five. The dualRMG layout cannot cope with a higher stack because the RMGs were already performing at their maximum capacity (consider the long truck service times caused by vessel productivity demand requiring both RMGs for vessel jobs from time to time). The twinRMGs should be able to process a larger volume because they are faster (4 m/s instead of m/s) and there are more cranes (82 instead of 70). The overall throughput increase equals 119% * 125% = 48%.This means the yearly throughput can be million TEU. The gate volume increases to 470 boxes per hour. If the 16 quay cranes should be able to achieve 48% higher peak throughput as well, the cranes must perform 40 to 42 bx/hr. Note: We consider linear increases in throughput and peak course these numbers are dependent on other factors too (such as berth capacity), but we ignore those factors in this study. The increased volume causes a larger demand on landside peak handling and a higher stack leads to more unproductive moves too (shuffles), so the demand on the RMGs is significantly will find out how badly this influences the performance. Results The impact on quay crane performance is negligible. With an increasing amount of AGVs the performance drops with 1%, as shown in Figure 4. The landside performance shows a bigger impact. Although the RMGs can handle the increased volume, the service times increase. Trucks delivering a container to the yard need to wait a minute extra on average。 this represents waiting for a free transfer point under the quay crane or waiting for correct sequen