Risk evaluation for container ships
Lee, Jun Hong
Date of Issue2016-05-12
School of Mechanical and Aerospace Engineering
Due to the increase in demand in trades, more demands for new builds, increase in fleet characteristics and vessel sizes are being identified. Therefore, improvement in container vessels design has been looked into for the past few decades. With this being said, this report will summarize the results of the consequences in terms of societal, environmental and economical risks according to the casualty records registered from 1990 to 2012. Three accident categories are being considered in this analysis which includes collision, contact and grounding. Event tree technique is employed in this case to study the combinations of various sequences of events for each accident category. Probabilities used in this report are either extracted from previous research paper or assumed according to engineering judgments. All consequences will be shown using F-N graph format. For societal impact, collision suffered greater consequences as the average cumulative frequency is relatively higher as compared to the other two accident scenarios. However, the societal risk of collision lies within the ALARP region. In the case of contact situation, due to low possibility of occurrence as a major accident, the societal risk is relatively as compared to other two accident scenarios. Therefore, under the ALARP principle, it is regarded in the negligible zone. As for grounding scenario, those scenarios with low fatality rate has a higher frequency of occurring, however, the societal risk lies in the negligible zone. But for scenarios with full fatalities rate, the overall societal risk lies in the ALARP region. For both environmental and economical impacts, collision appears to be the accident scenario suffering the most consequences as the average cumulative frequency observed is the highest among the three categories. This is probably due to the higher initiating frequency for collision accidents to occur leading to larger amount of fuel and dangerous goods leakages and also higher losses in terms of ship damages and cargo losses. For grounding scenario, the amount of leakages and monetary losses are relatively high but not as high as collision accident. When multiple damages are sustained during a grounding event, it has higher chances of flooding to occur leading to unbalance mass system. Under these circumstances, majority of the times, structural failure will occur and lead to sinking of vessels. Therefore, high amount of leakages and damages are incurred. For contact, in most cases, only minor damages such as scrapping of paint work or small deformation on the hull surface are sustained; therefore, smaller amount of leakages and economic losses are sustained.
Final Year Project (FYP)
Nanyang Technological University