Container ships that lose some of their cargo not only suffer an economic loss, every accident leads to major ecological damage. The "TopTier" project is investigating how cargoes can be better protected in extreme weather.
Anyone who has ever had the chance to look at a loaded container ship up close is probably impressed by its size. Up to 25,000 of these steel boxes are stacked on deck, right up to the sky. Most of them are transported across the oceans without incident. But in heavy seas, cargo can slip and containers can go overboard. They are measured in TEUs, where a TEU is equivalent to a 20-foot container - that is, about seven meters long. The World Shipping Council, an advocacy group for shipping companies, reported a loss of 1,400 TEUs in 2020. But the numbers are rising, with more than 2,500 containers going overboard from October 2020 to March 2021 alone. In November 2020, the container ship ONE Apus alone lost 1,816 containers, and in January 2021, Maersk Essen complained of a loss of 750 of the metal boxes. This not only leads to ecological and economic damage, containers floating in the water additionally pose a collision hazard. With its Institute for Design and Strength of Ships, TU Hamburg is involved in the industry project "TopTier" with tests. The aim of the project is to reduce the probability of containers being lost at sea and to identify improvements in ship safety for the coming decade.
Shipping: discussion on safety and environmental impact.
"Container shipping is essential to the modern global economy. Although accident rates are extremely low in percentage terms, the absolute numbers are too high. At least 1,000 containers are lost at sea every year, and many people are injured during handling operations," explains Prof. Sören Ehlers, who is responsible for the TU project. In the past, there has already been serious damage to the coastal marine environment. This has led to discussions among the public and politicians about the safety and environmental impact of modern container ships - so that both politicians and industry are now being called upon to respond to potential problems in container securing.
But why is it so difficult to adequately secure containers on ships in the first place? The answer lies in the construction of the ships. They have become larger and larger in recent years to accommodate more cargo. Experience with new ship sizes, their operating conditions and loading mechanisms is therefore still limited, and in the case of extreme events such as particularly bad weather at sea, these uncertainties increase. "Current limits do not cover all factors involved in the newest classes of ultra-large container ships. A better understanding of these conditions and mechanisms of action is therefore necessary," says shipbuilding expert Ehlers.
Measuring container ship loadings and wave motions
The TopTier project is divided into several tasks. The first is to identify the most important aspects of cargo stowage and securing on container ships identified in 2020 and to verify them with the help of interviews and questionnaires with, for example, shipping companies, ship crews and terminal workers. "We then focus on how to deal with current cargo securing practices. To this end, project coordinator MARIN has tested ships in the wave channel and measured ship movements. From this data, we can deduce how size, cargo and loading condition react under certain wave conditions," says Prof. Ehlers, explaining the individual criteria. In the further course of the project, things will get particularly exciting: The researchers want to find out how it is that containers slip. To do this, they are studying the ship's movements; in particular, horizontal bending and torsion, a helical twist. These effects are tested through a combination of measurements, model tests and numerical studies. Finally, the behavior of the ship's crews also plays a role. Ideally, they should be able to actively prevent incidents. The results of the project will be passed on to the relevant shipping authorities, where they will be implemented for all concerned - so that a level and safe playing field continues to apply both at sea and on land.
The international project is led by the Dutch research institute MARIN. For more information, visit https://www.marin.nl/en/jips/toptier.
