Ongoing technical developments in recent decades have led to an increase in the information presented to the operating personnel on these machines. In order for operator stations on construction machinery to be designed that are safe and usable, consideration must be given to the processing of information by the machine operator. This must include conditions such as the work activity, equipment, work environment and work organization. Field studies were therefore to be conducted into the use of aids to vision, such as mirrors and CCTV systems, in actual operations during selected manoeuvres involving hydraulic excavators. At the same time, the acceptance of protective measures, such as safety belts, was to be estimated.
The activity of excavator operators was first analysed in order to structure the activity and to identify tasks and manoeuvres relevant to the subsequent studies. A mobile eye tracker was trialled on construction sites and adapted for this context. A device was also developed for recording the work tasks by observation. Field studies were then conducted in which the eye movements of machine operators were recorded by the eye tracker whilst working tasks and manoeuvres were recorded at the same time by observation and by video recordings. The use of aids to vision and of protective measures was estimated in addition by means of questionnaires and interviews. Following preliminary processing of the recorded data, the eye-movement data were merged with the observation data for evaluation of the use of aids to vision and other sources of information during selected manoeuvres, such as reversing.
A task recorder was developed and used successfully in the field studies for analysis and documentation of tasks during work. The eye tracker was also converted for the performance of measurements over a period of several hours on operators of mobile machinery on construction sites. Based upon analyses of the activity and individual tasks, discrete excavator movements, such as reversing, were identified as being critical, and their relevance in the work process was demonstrated. The analysis of the tasks combined with the eye movements ultimately showed that all aids to vision (e.g. CCTV systems and mirrors) were used both on their own and in combination during reversing. Variations in the frequency of use were observed as a function of the work equipment, work environment and work organization. This in turn yielded further findings concerning the use of sources of information and the mode of working of machine operators during critical excavator movements. These findings can be examined further in future studies. The questionnaires concerning the acceptance of protective measures yielded preliminary information for the improved design of safety belts.
construction industryType of hazard:
machine safety, man-machine interface, technology designDescription, key words:
Earth-moving machinery, hydraulic excavators, viewing aids, camera monitor systems, information acquisition, eye-movement analysis, task analysis