A study for optimisation of double cycling in container ports



Jang-Ho Song, Duty Manager, Pusan Newport Co., Ltd, South Korea


The following is a summary of a recent Masters Thesis by Jang-Ho Song, who was enrolled in the Port-logistics Programme at the Graduate School of Korea Maritime University, Busan, South Korea. In August 2007 it was awarded the Minister Prize from the Ministry of Maritime Affairs & Fisheries as the top thesis in the department.


In a rapidly changing marine environment, worldwide container terminals are concentrating on improvement in productivity to reinforce marketing power and to obtain competitive power. In modern terminals, equipment, and facilities, productivity is rapidly developing. Specifically, productivity is progressing with a great deal of  investment focused on improving equipment functionality and infrastructure.

Double cycling is a technique that can improve productivity without additional investment in current equipment and infrastructure. All it requires is operational training for manpower and research in operation methods.

If the research into double cycling is revitalised, crane productivity will improve dramatically because of double cycling’s operational technique of maximising  equipment efficiency (Quay crane, RMG/RTG, Yard tractor).

Unfortunately, it is very difficult for terminal operators to find out the starting point of double cycling because of the various loading & unloading patterns and conditions. Therefore, terminal operators are more likely to fail to find out the optimal starting point of a double cycle and maximise its frequency.


Experiencing these same challenges in the process, I made efforts to find out the optimal starting point and finally discovered a formula for it. It was verified that the formula’s precision is perfect through extensive testing. This theory on double cycling focused on making a formula to find out the optimal starting point of double cycling to maximise its frequency. It can be applied to various ships’ stowages in common. Double cycle’s progress direction types and decision element

In order to decide a double cycle’s stevedoring direction, the following major elements need to be taken into consideration: maximum frequency of the double cycle, convenience of QC operators and field workers and planning.

Terminal operators must compare these elements and variable work conditions in order to find an optimised method, and should refer to three formulas to find  respective optimal starting points of a double cycle for three kinds of stevedoring directions.

A double cycle’s stevedoring direction can be divided into ‘from starboard to portside,’ ‘from portside to starboard’ or ‘zigzag type.’ For greater influence on productivity and work flow, it will be more beneficial that the stevedoring direction goes in one way, such as ‘starboard to portside’ or ‘portside to starboard.’ The third type can maximise the frequency of a double cycle, but it is very difficult for field workers to understand work flow. Thus, sufficient preparation and training should be performed before its application.

Cookie Policy. This website uses cookies to ensure you get the best experience on our website.