Container terminals employ a variety of real-time locating services (RTLS) that range from DGPS/INS to RFID technology. Terminal equipment positioning systems, extended real-time monitoring systems, and auto hand off systems are all currently applied in container terminals that are operating today. Below are some of the existing RTLS technologies and their pros and cons, as well as an insight into how they are used in various types of terminals.
GPS is a viable option for any container operator that wants to visualise terminal processes with minimum investment. The GPS visualiser can track terminal trucks and gather basic information such as movement history, speed and status of trucks that are loading containers. However, there are limits to the accuracy of pinpointing locations. Weak satellite signals lead to low accuracy levels, and signal interferences are high due to thick layers of containers and heavy equipment such as cranes and reach stackers. Therefore we can state the positives and negatives as below:
• Pros: Inexpensive, easy installation and implementation, as well as less space required by small devices
• Cons: Relatively low accuracy, vulnerable to satellite interferences and this often leads to lost targets
DGPS AUGMENTED BY INS
DGPS (Differential GPS) decreases the margin for error to less than 1 metre by using the fixed position of reference stations in the terminal yard. However, DGPS is also vulnerable to signal interferences; therefore it requires additional sensors to enhance