Ergonomic assessment of a memory seat for a bus driver's workplace

Status:

completed 06/2001

Aims:

Bus drivers spend a large proportion of their working day in a seated position. In order to avoid occupational health hazards, it is therefore essential that drivers' seats fulfil not only technical but also ergonomic criteria. The driver's workplace in new buses generally includes an ergonomic driver's seat which offers drivers a wide range of adjustments, enabling them to find a seating position which is both comfortable and conducive to good health. These adjustments are often not exploited to the full in everyday use, owing to time constraints, inconvenience, or lack of instruction. In order to simplify selection of the various seating parameters, a seat memory was therefore developed in which the ideal seat position for each individual driver can be stored on a memory card. This system has previously only been tested in a laboratory, however. Consideration therefore had to be given to whether a memory seat is of benefit in everyday use and actually contributes to a more ergonomic seating posture at the bus driver's workplace.

Activities/Methods:

A proband collective comprising approximately 25 bus drivers of both sexes, who are familiar with the new bus driver's workplace (without seat memory function), is selected for the purpose of the study. The study is divided into four phases. The bus drivers are given the opportunity to acquaint themselves with the adjustment facilities of the seat during a familiarization phase. This is followed by a measurement phase performed upon the collective, during which the trunk angle and the seating position selected by each proband are recorded continuously as they work. The trunk angles are recorded by a measurement system developed by the BG Institute for Occupational Safety. The associated seat settings are stored on a computer connected to the memory seat. At the same time, video recordings are made of the workplace situation. During the subsequent laboratory phase, the optimum seat position is identified for each individual proband which leads to assumption of an ergonomic trunk angle determined by a previous research project. These data are then available for the final (confirmation) phase. This phase evaluates whether the settings of the memory seat determined during the laboratory phase actually result in the subjects' assuming the ergonomic angle, and also provides the opportunity for consultation of the subjects with regard to their acceptance of the new seat position.

Results:

The study revealed considerable ergonomic deficits in the driver's seated posture when the memory seat was not used. The use of the memory function resulted in a considerable improvement in the seated posture for the entire bus driver collective. Four particular seat setting functions should be memorized: seat height, fore/aft seat adjustment, seat back inclination and seat cushion inclination. The subjective impression of ease of use and seat comfort was almost exclusively positive.

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