During the use of a hydraulic excavator, the superstructure, arm, tools or entire machine move, frequently causing collision accidents during travel and rotational movements. In order to perform these manoeuvres, the machine operator must receive a range of information from the machine's surroundings. Where a direct view is not possible, visual aids are intended to permit an indirect view of obscured areas. Owing to the increased use of CCTV systems on construction machinery, both the volume of information and the form of its presentation have changed considerably in recent years. Besides the work task and the conditions under which it is performed, processes of information processing must also be considered for safe and usable design of aids to visibility.
In response to an initiative by the Sub-committee Civil and underground engineering of the DGUV Expert committee Construction and the German Social Accident Insurance Institution for the building trade (BG BAU), the use of aids to visibility was to be studied. Field studies were conducted in Project 5126. The analysis of eye movements focussed upon specific areas (such as aids to visibility) during selected excavator movements (such as reversing). Rotational movements and sideways travel were also found to be associated with collision accidents. Analysis of the eye movements was to be extended to further areas around the machine (such as the areas to the side). It also became clear that more detailed analyses of the duration of eye movements are required. These aspects were to be considered in this project.
Data on eye movements of machine operators and on excavator movements that were recorded in IFA Project 5126 were employed for the study. Eye-movement data recorded during rotational movements and sideways travel were prepared in advance for analysis purposes. Further relevant areas were also specified for assignment of the eye movements. Finally, eye movements were evaluated with respect to their frequency, progression, combination and duration. The results were documented and assessed in combination with those of the preceding project.
Based upon the analyses, critical rotational movements and sideways travel movements were identified and their relevance in the work process clarified. Interpretation of the eye movements revealed that during clockwise and anticlockwise rotational movements and during sideways travel, all aids to visibility (e.g. mirrors and CCTVs) were used both individually and in combination. Differences in usage were observed between different movements. Analysis of the characteristic of eye movements over time revealed that aids to visibility were used both before and during excavator movements, which suggests that they served different purposes (e.g. collision avoidance vs. navigation). This observation was extended by analysis of the duration of eye movements, which yielded similar results for certain aids to visibility. Finally, further frequently vie-wed areas were identified, such as parts of the chassis and parts of the area around the machine. Together with findings from the preceding project, a more comprehensive understanding was thus gained of the use of sources of information during work involving hydraulic excavators. This information can be exploited for the identification of measures by which collision accidents involving construction machinery can be avoided. These measures could include the extending of CCTV systems to cover the right-hand side, and the compilation and application of design requirements for aids to visibility on hydraulic excavators.
construction industryType of hazard:
design of work and technology, questions beyond hazard-related issuesCatchwords:
(digital) information processing, man-machine interface, technology designDescription, key words:
earthmoving machinery, hydraulic excavators, aids to visibility, CCTV systems, reception of information, eye-movement analysis, task analysis