Skip to main content

Breakdown in human adaptation: Performance decrement


It was the aim of this CA to deal with performance decrements at the working place in transport systems. As such, it was mainly focused on the population of traffic operators, ie on those who are professionally employed in the guidance and control of surface, sea- and airborne vehicles.

The integration of operators into modern transport systems gives rise to frequent conflicts with the limits of human adaptability. There are indications that these conflicts lead to an increase in medical, psychological and social problems. As a consequence, this maladaption results in higher risks of performance decrements, human errors and traffic accidents. It was the purpose of this CA to address these issues and to identify the most significant parameters, methods, and results related to medical, psychological, and social problems affecting operator performance in transport vehicles. Special attention should be paid to issues being uniform or similar for different transport systems.
European countries have collaborated in research into human performance in transport operations, the safety and reliability of which are of vital interest for the economy of the European Community. The efforts focused on irregular and abnormal work and rest hours, medical and psychological care, automation, and simulation.

From analysis of statistics it was concluded that human factors are far more likely to be the cause of accidents than technical failures. This is true for all transport systems, and it appears that operator performance is of central significance for traffic safety and reliability.
There are indications that limits to human adaptability in handling modern transport and the permanently high workload and time pressure on operators may lead to increased stress reactions and to higher health risks.
Due to automation and new technologies in traffic systems, a shift can be observed from physical to mental activity and from executive to controlling and monitoring behavior. Consequently, mental processes play an increasing role in determining the workload in most transport operations. Automation has been offered as one solution to the increasing number of workload related problems, while it often simply replaces one source of workload for another, rather than accomplishing a significant reduction.
In some cases, apparently human limitations reflect the consequences of poorly designed controls, displays, and automatic subsystems. In other cases, the imposed demands simply exceed human capabilities either momentarily or for extended periods. Finally, the operational environment imposes additional demands (eg irregular work and rest), combining with other sources of workload to exceed operator's capabilities and to enhance the risk of breakdown in performance (human error).
Human error is poorly understood and inadequately recorded, partly due to the data collection in many accident reporting systems being determined by accidental consequences, rather than by accident causation. Transport systems cannot be designed and run efficiently simply by reference to objective risk estimates, calculated from official accident statistics. The key to safer transport systems is a better understanding of subjective risk.
Breakdown in human adaptation to the rapidly changing conditions of modern life has become a matter of serious concern throughout the world. Considerable research activities have been initiated to study the basic mechanisms underlying adaptation and maladaptation. There is much evidence the poor adaptation to adverse environmental conditions and lead to impaired well-being and a variety of disorders. At the work place, a breakdown in adaptation results in performance decrements, when an individual is unable to cope with the demands of his task. This may be caused by excessive mental or physical workload, including social and psychological conflicts as well as task requirements which range from simple, monotonous and repetitive operations to complex, fast and decision-taking actions.

Efficient transport of goods and people is essential to the functioning of modern society and will remain so, in spite of the growth of information technology. Human performance is a crucial component of most transport operations, and human errors can have serious impacts on the public. For the economy of the European Community, safety and reliability of transport systems are of vital interest.

Funding Scheme

CON - Coordination of research actions


Deutsche Forschungsanstalt für Luft- und Raumfahrt eV (DLR)
Linder Höhe
51140 Köln