KANBrief 4/15

Diesel particulate filters on construction machinery: clean air or good visibility?

In the future, the Berlin regional administration will award public construction contracts only to companies using low-emission construction machinery. One means by which the required emission limits can be observed is by the retrofitting of diesel particulate filters to the machinery. This measure must not be allowed to compromise the existing safety level. In particular, the filters must not impair visibility from the driver's seat.

In order to reduce diesel particulate emissions from construction machinery to a minimum, the Berlin regional administration is adopting a new approach. Reduction of the harmful substances is not being made a legal requirement; however, from January 2016 onwards, invitations to tender and public construction contracts will specify higher environmental standards by which the emissions of harmful substances are to be reduced. These standards will require construction machinery and mobile machinery to satisfy certain exhaust emissions standards, either ex-works or by means of a retrofitted certified particulate filter (see "Senat für Umwelt, Verkehr und Klimaschutz, Berlin" (in german)). As a result, many construction companies will have to retrofit their machinery with diesel particulate filters in order to continue to secure public contracts. It can be anticipated that this approach will be adopted by other regional administrations in Germany. This will lead to retrofitting being necessary on a major scale in the coming years.

Diesel particulate filters generally take up a lot of space. As a result, they cannot always be accommodated under the bodywork of the machine and must often be fitted externally instead. From an OSH perspective, this is accompanied by the challenge not only of properly engineering the retrofit solution, but also of preventing the machine's safety level from being reduced as a result. The Berlin regional administration has drawn up a guide (in german) that particularly addresses the technical background to the filter technology, retrofitting itself, and operation of the machines with particle filters. The text also contains information on the safety aspects that must be considered.

Preventing new risks from arising

When particle filters are retrofitted, it must be ensured that the new elements do not result in changes to the machine that give rise to new or elevated risks. This entails more than mere selection of a suitable particle filter and assurance of its serviceability. For example, it must be ensured that fitting of the filters does not cause damage to safety equipment such as roll-over bars and roof guards, and that excessively hot components do not become accessible as a result. The emergency exits from the driver's cab provided by the manufacturer must also not be obstructed by the retrofit measure.

Consideration for current developments concerning visibility

A location for the filter should ideally be found at which it does not impair visibility from the driver's seat. Should this not be possible and visibility be impaired by the particle filter, the operator of the machine must take measures to restore the original visibility conditions; use of the machine must be safe in accordance with the state of the art. Preference should be given to technical solutions. Additional aids to visibility in the form of CCTV systems should be preferred to mirrors.

The relevant standards governing visibility conditions on earthmoving machinery should be observed during risk assessment and during the selection and siting of the aids to visibility. These standards are however currently in the process of revision (see KANBrief 4/14). In Germany, the DGUV Civil and geotechnical engineering sub-committee has therefore published recommendations (in german) serving to provide practical assistance to operators of earthmoving machinery for the purposes of risk assessment.

Provision of support

In consideration of the anticipated high number of machines requiring upgrading in the coming years, the OSH lobby envisages a need for information, particularly for construction companies, the majority of which are small. The industry associations are called upon to raise awareness of the issue and to provide practical information materials that describe the retrofitting measure consistently, and that also address its impact upon safe use of the machines.

Dr. Michael Thierbach