This paper on VTS (vessel traffic service) operator stress explores the relationship of stress to workload, stress-management strategies, and how cooperative humanmachine systems can reduce stress. The trials detailed and the solutions offered are the result of work conducted by maritime group ‘Designing Dynamic Distributed Cooperative Human-Machine Systems’ (D3CoS) – a research project funded by the ARTEMIS Joint Undertaking. The goal of D3CoS (which concluded February 2014) was to create methods, tools, and techniques for developing distributed, cooperative, human-machine systems that reduce development costs and time. The project asked questions such as ‘how can machines ‘cooperate’ with users during stressful and high workload situations that will result in higher safety’, and ‘what tasks can a system take on to ease the burden on operators?’
Why reduce operator workload?
In VTS areas that are not busy, operators may experience what is called ‘underload,’ meaning there are periods of inactivity that can lead to boredom and distraction. Here, organisations are not looking for ways to reduce workload, but rather to increase it. Some VTS areas, such as Singapore, Rotterdam, Hong Kong and the Dover Straits are remarkably busy. Other VTS centres are expanding their area of responsibility, which will increase operator workload, while not increasing staffing levels. But for those individuals who work in, or whose organisation is responsible for either a very busy area or a very large area, managing operator workload is important. Operators need to identify and respond to critical situations but if they are overloaded with tasks – no matter how appropriate to their responsibilities – they might not be alerted to circumstances that require their attention.
Why reduce stress?
In the short term, being stressed can make one more alert. Stress in an emergency situation can be a positive thing. Too much stress, however, can potentially lead to several negative consequences. In the short term, when stress has accumulated over a period, it can lead to headaches, bursts of anger, physical pain or discomfort, poor judgment, fuzzy thinking, and loss of precise motor skills. In the long term, stress can lead to a number of illnesses, including depression, anxiety, heart attack and stroke. The wellunderstood consensus is that experiencing stress in appropriately engaging situations is necessary and good, but if stress persists over a long period, the effects are overwhelmingly negative. Stress levels, therefore, should be managed and relieved in VTS operators to ensure safe shipping. The need to reduce stress and the effects of stress in operators are well-known. It is why operators rotate positions in the Dover Channel Navigation Information Service and why the Maritime Port Authority of Singapore hands over operations to another operator every 45 minutes for its busiest VTS areas. It is also why the IALA VTS operator course V-103/1 Module 7 teaches VTS operators about the causes of stress and how to manage it.
How is operator workload and stress connected?
Some people point to the composition of traffic as a stressing factor. The berthing of a supertanker is more stressful than the berthing of a small container vessel, one harbourmaster noted. Others point to task type, not task load. A collision in one’s area of responsibility creates more stress than multiple VHF requests for weather data, for example. The D3CoS project carried out trials with real VTS operators to understand the relationship between workload, type and stress. These trials consisted of simulated VTS control tasks. They were conducted in two rounds, with experienced maritime traffic operators from Halifax, Canada and the Norwegian Coastal Administration acting as the VTS operators. They were instructed to control a specific area and execute realistic tasks with physical responses measured by connecting the operators to monitoring equipment. Operators also finished a post-testing questionnaire and the trials were recorded by video and audio.
