KANBrief 2/10

See and be seen: the use of machinery on construction sites

The use of modern construction machinery is substantially responsible for construction work becoming increasingly more productive and also more ergonomic. The frequently close proximity of human workers and machinery on construction sites is not without hazards, however. Poor visibility is one of the aspects which repeatedly lead to accidents. BG BAU is tackling the problem by means of new provisions in standards and by the “Fight the Risk” campaign.

It goes without saying that on construction sites, standing within the danger zone around earthmoving equipment such as excavators, loaders, tracked bulldozers or compaction equipment is prohibited. Should workers nevertheless need to enter this zone for work-related reasons, they may do so only in observance of special safety measures. For example, the operator of the machine must interrupt work when persons are present in the danger zone.

Problem: poor visibility

Direct visibility of the machine’s path and working area from the operator’s seat is often obstructed on large construction equipment, owing to its design. On machines equipped in accordance with EN 474, Earth-moving machinery – Safety, rear-view mirrors aid the operator’s visibility. For measurement of the field of view, this series of standards refers to the methods described in ISO 5006, Earth-moving machinery – Operator’s field of view – Test method and performance criteria.

During the most recent revision of ISO 5006, requirements were formulated for the first time concerning visibility of the area immediately surrounding the machine. Manufacturers and OSH organizations worked closely together for this purpose. Whereas previously, a 12-metre radius was measured around the machine, measurement is now also performed at a distance of 1 m from the periphery of the main machine body. For this purpose, a test body (rod) with a height of 1.5 m must be visible from the operator’s workplace; no more than 30 cm of this rod may be obscured.

Owing to the reference in EN 474-1 to ISO 5006:2006, the requirements for the close field of view now also apply to new machines in Europe. Since 30 November 2008, only the updated version, EN 474-1:2006, has had the status of a valid harmonized standard. It alone gives rise to the presumption of conformity with the EU Machinery Directive, which governs placing upon the market.

Retrofitting for better visibility

As a result of the new provisions of the standard, larger earthmoving machines have been equipped with additional aids to visibility since around 2009. Such equipment is of course also available for all machines manufactured earlier. Many an existing obstruction to visibility can now be eliminated by design changes, for example by sloping engine covers, relocation of exhaust systems, etc. Additional rear-view mirrors which are more appropriate to users’ needs are in some cases a suitable solution, and in many cases, the fitting of CCTV systems is an intelligent alternative. Of decisive importance is that visibility is made possible. Detection systems and reversing horns are not adequate substitutes.

Upgrading, the cost of which is usually moderate, is urgently recommended, and not only for reasons of occupational safety. A machine driver who can actually see what he is doing rather than merely driving “blind” is able to work faster and more accurately and to avoid damage to the machine. The investment therefore really pays off.

In the context of the “Fight the Risk” prevention campaign, BG BAU is drawing attention to the subject of “seeing and being seen” (in german). The campaign aims to make clear that engineered measures for improving visibility for machine operators are important, but not sufficient on their own. Instead, the aim is for everyone working on a construction site to be motivated to behave (and to dress) in such a way that they are visible to machine operators at all times. “We’ll be seeing you” – a motto that may save lives.

Walter Ensinger