KANBrief 2/18
The accessing of construction machinery – in order to access the driver’s station, for refuelling or topping-up of other fluids, or for the performance of maintenance work – is a scenario in which occupational accidents frequently occur. In order to acquire a better understanding of the reasons for the accidents, the French National Federation of Public Works conducted ergonomic studies in a number of companies. These yielded a number of observations and strategies for solutions, aimed at both the operating personnel and the machinery manufacturers.
In order for the causes of accidents arising during the accessing of construction machinery to be understood, an ergonomics study was conducted involving 56 drivers at 31 construction sites in 14 French companies. The study revealed the actual conditions on the construction sites and the diversity of tasks performed by the machine drivers. It showed that besides performing their core task (reliable operation of the machine), the operating personnel are required to conduct numerous additional tasks. They must for example leave the machine in order to refuel it; complete simple maintenance tasks; coordinate personnel on the ground; assist with material transport, etc. The study showed that the drivers exited and accessed their machines up to 50 times each working day.
Personal, organizational and timing influencing variables (such as the driver’s experience, physical characteristics and flexibility; time pressure; technical outages; delivery delays) can be used on each construction site to analyse the tasks actually performed by the drivers and to understand the effects upon their movements. Maintenance tasks (such as lubrication, cleaning, refuelling, filter changes) may for example necessitate up to a hundred movements per day on the machine. Design solutions must make the tasks less onerous and must reduce the risk of tripping, slipping and falling caused by unfavourable postures and excessive use of force to a minimum.
The access systems must therefore be suitable for swift, practical and above all intuitive use by the user. Unfortunately, many manufacturers evidently continue to provide access arrangements that are unsuitable in practice: with bottom steps that are too high, steps that are offset with respect to the cab, insufficient support points, grab rails and handrails that are out of reach, platforms that are too confined, etc.
These deficits persist despite the fact that normative requirements have long been available for access systems on earth-moving machinery. The ISO 2867 international standard, Earth-moving machinery – Access systems, the most recent version of which (2011) has been adopted as EN ISO 2867, has been revised several times. It sets out requirements for access arrangements to the driver’s station and to routine maintenance points on earth-moving machinery. The standard describes the design of steps, ladders, walkways and platforms, railings, handrails and openings.
The standard’s suitability for use in practice is however still in doubt, particularly with regard to wheel excavators, on which it is no longer permissible for the wheels and tyres to form part of the access arrangements. Furthermore, the dimensions of walkways, platforms and ladders, which form the core of this standard, have not been updated for almost 20 years.
Access arrangements to machines continue to be a prime issue of concern across the sector. Improvements to organization on construction sites, the raising of awareness among construction machinery drivers, and also better design of the machines and corresponding amendments to the standards are required in order for the challenges to be met that are presented by work on construction sites, both today and in the future.
End users have a crucial role to play in standardization activity. They should assist manufacturers in gaining a better understanding of the interaction between human being, machine and conditions on the construction site. The requirements then become self-evident. Improving the design of machines is essential in order to ensure their safe use and their performance, and thus ultimately to ensure productivity on the construction site.
Further development of the drivers’ actual tasks must play an essential part in risk assessment: as a starting-point for design, it has a decisive influence upon human safety, for example with regard to access to the machine, and to visibility from the driver’s station – areas in which there is still much work to be done.
Catherine Jarosz
National Federation of Public Works
(Fédération Nationale des Travaux Publics [FNTP], France)