# Towards a Reference Architecture for Cargo Ports
## 2 Background
### Cargo Ports
#### 2.2.3 Container Terminal Operations
To prevent multiple restows or misplaced containers, the efficient assignment of the location or address of the container is of primary importance. Without efficient ways to assign container addresses, multiple restows are likely [39]. Containers are assigned specific addresses before entering the storage yard. In automated or semi-automated container terminals, intelligent stacking cranes operate using the optimum path, overlapping horizontal and vertical motion. Multiple ASC cranes in the yard are coordinated to avoid waiting times, so stacking cranes are able to deliver variable volumes of containers in a short time. Automated equipment is operated without  
Figure 3: Modern container terminal. unnecessary accelerations and deaccelerations, and huge energy savings can be made. With intelligent automation, all the operations of the ACT can be comfortably handled from a central control room, which makes terminals safer and the working environment more ergonomic. Remote operation and on-board cameras provide better views than what is possible from a crane cabin in situations like landing containers on a ship or vehicle or handling hatch covers close to the ground [37; 38]. Another important element of a container terminal is the movement of containers between the STS cranes and the storage yard. STS cranes unload a ship and place the containers in trailers or shuttle trucks. These shuttle trucks move the containers to storage locations in the yard. This operation is a closed loop, as their only function is to shuttle the containers from the ship to the storage yard. These trucks are local, and they usually do not leave the terminal. A collection of shuttle trucks is called a gang, and they may be automated guided vehicles (AGV) in larger terminals. The road network for these unmanned robotic transport vehicles is defined by electric wires or transponders in the ground, which enable the accurate positioning of these vehicles [40]. The number of shuttle trucks also needs to be considered. Too many trucks in the system cause long lines at the crane and long waiting times for service; conversely, fewer trucks in the system will result in idle stacking equipment. Containers, which are stored in the storage yard, leave the terminal on input/output trucks to reach their final destinations. Because of the high cost of keeping a ship in port, it is important to keep the dock crane operating without delay to turn the ship around as quickly as possible [38]. A great variety of container terminals exist, mainly depending on what type of handling equipment is used in the system. The decision on which equipment to use depends on several factors. Space restrictions, economic reasons, and even historical reasons play an important role. A basic factor is the size of the space that can be used for a terminal. If space is restricted, gantry cranes to store the containers are preferred. A decision for AGVs and automated gantry cranes can be made in cases of high labor costs and new terminal construction. Historical and cultural reasons must be considered if container terminals are enhanced or modernized. Because space is becoming a scarce resource, a tendency toward higher storage is to be expected [41].