Whole-body vibration of railway locomotive drivers

Status:

completed 03/2002

Aims:

Back pain suffered by railway engineers frequently results in increased disability. The whole-body vibration impact arising over longer work periods must be regarded at least as a contributory factor in the incidence of back pain. Suitable seats which also have facility for vibration damping in the horizontal plane may be considered as a preventive measure. The purpose of the measurement campaign was to analyse the vibration impact and to draw up criteria for effective prevention measures.

Activities/Methods:

The vibration impact was measured on the seats of a range of freight and passenger train locomotives in the USA. The seat cushions and the mounting points of the engineer's seat, frequently also the seats of the conductor and the stoker, served as the measurement points. The recorded vibration data was analysed with regard to characteristic over time, isolated and repetitive shocks, and dominating frequencies taking also the maintenance condition of the locomotives and rails into consideration. A suitable test spectrum for engineers' seats, both vertical and horizontal, was to be drawn up.

Results:

The results of measurements performed on 22 locomotives, in routine and typical operation but in some cases on track in very poor condition, reveal that vibration impact perpendicular to the direction of travel and in the vertical axis of vibration (spine) is in the same order of magnitude and is higher than in the direction of travel. The results were assessed in accordance with international standard ISO 2631-1:1997 "Mechanical vibration and shock - Evaluation of human exposure to whole-body vibration - Part 1: General requirements". The mean frequency-weighted acceleration in the vertical axis was 0.32 m/s². This value is in the same order of magnitude and lower than the corresponding values for road and off-road vehicles. Detailed analysis revealed however that the vibration impact is characterized by frequent shocks. In some cases, the guide values for the parameters stated in ISO 2631-1:1997 were exceeded; were the usual equivalent values alone to be employed, the vibration impact may therefore be underestimated. A seat test spectrum was calculated for the vertical axis and another spectrum for the axis of vibration perpendicular to the direction of travel. In addition to reduction of the shock impact, proper support of the body by the seat is important for an improvement of the worksituation; this applies particularly to the axis perpendicular to the direction of travel. Continual monitoring of the seat function and its mounting is required; excessive play can lead to non-linear amplification of the vibration.

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