Validation of Heavy Work by TNO: Initial Insights and Key Considerations

Publication date: 11 June 2026

Since 1 April 2026, the helpdesk of the Expert Centre for Heavy Work at TNO has been operational. Collective labour agreement (CLA) parties can submit their delineation of the target group for the RVU exemption threshold for validation. The expert centre provides advice on this delineation. Although the first formal outcomes have not yet been published, clear lessons learned and points of attention are already emerging in practice. In this update, we outline the most important insights.

Two TNO approaches

In order to define the target group for the RVU exemption threshold, CLA parties must objectively substantiate which roles or activities qualify as heavy work. A sound application requires expertise in occupational health and safety, which in practice means that (external) experts need to be engaged. CLA parties and their experts can develop this substantiation via two approaches, after which TNO will carry out its validation.

1. Proprietary approach or existing documentation

CLA parties may opt for their own methodology. For example, the Dutch Railways (NS) have applied a methodology based on the Heavy Work Model developed by FNV Havens. When using a proprietary approach, existing sources such as a (validated) RI&E may be used. If this route is chosen, it must be clearly explained which roles are considered physically and/or mentally demanding, which job characteristics make the work physically and/or mentally demanding, and how this conclusion has been substantiated, including the methodology applied and the documentation used.

2. TNO methodology for demanding work characteristics

An alternative is to use the methodology developed by TNO, which can be applied through a practical online tool provided by TNO. Social partners and experts can use this tool to assess, per role or job category, the extent to which physically and/or mentally demanding work characteristics are present. The assessment is based on the now well-established demanding work categories: working hours, physical strain, environmental exposure, psychosocial strain, and cognitive load. These categories are further subdivided into specific work characteristics, which must be substantiated quantitatively and/or qualitatively.

Is it necessary to assess all burden categories in the TNO tool?

For validation purposes, it is generally sufficient to demonstrate convincingly that at least one category involves demanding work characteristics. If other categories are not applicable, this must be explicitly documented. In other words, omission is only permitted if properly substantiated.

Mitigating measures

A recurring element (within the TNO tool) is the focus on mitigating measures (such as lifting aids or phased retirement schemes). Even where demanding work characteristics are clearly present, it is expected that CLA parties explain which measures have already been implemented to reduce the burden, and why further measures are not feasible or do not provide sufficient impact. Notably, the TNO tool indicates that the existence of mitigating measures does not affect the final assessment that a particular role entails increased health risks.

Clustering of roles

Whether an individual employee actually performs heavy work is not decisive. What matters is whether the job category can objectively be classified as heavy work. In practice, this means that roles can be grouped into clusters. While this approach makes the analysis more manageable, it also imposes requirements on the classification. Roles within a cluster must be sufficiently comparable, meaning that the same demanding work categories apply. It is therefore important that the objective nature and characteristics of the job category are clearly described and substantiated.

Employment history and exposure duration

It is also notable that factors such as employment history or the duration of exposure to heavy work are not taken into account in TNO’s validation. The expert centre does not (yet) apply criteria for this, due to the lack of uniform scientific consensus. This means that the assessment is limited to the nature of the role and its associated work characteristics. CLA parties may, however, choose to incorporate such factors in the design of their scheme, but this is separate from TNO’s validation.

Conclusion

CLA parties aiming to delineate heavy work must make explicit choices, provide a methodologically sound justification, and demonstrate that alternatives have genuinely been explored. The first formal TNO opinions are expected to further refine this framework. Until then, one principle clearly applies: the stronger and more objective the substantiation, the greater the likelihood that work will be classified as heavy.