How do you make the risk of an accident at work measurable and comparable? And, perhaps more importantly, how big is the damage? Is a forklift driver who works for a construction company more or less likely to be injured than his colleague standing on a scaffold? And if the answer is "less likely," how much less? To answer these kinds of questions, RIVMNational Institute for Public Health and the Environment has developed the Occupational Risk Calculator (ORCA) model. 

The model was developed in commission of the Ministry of Social Affairs and Employment (SZW) and is based on the analyses of   (underlying) causes of serious accidents that are reported to and investigated by the Inspectorate SZW (see also the topic Storybuilder). 
The model predicts probabilities of an accident with serious consequences, which are fatality, permanent injury or recoverable injury with hospitalisation within 24 hours.

The model is described in the RIVMNational Institute for Public Health and the Environment -report 'The quantification of occupational risk. The development of a risk assessment model and software
Questions about the quantification of occupational risks based on this model, can be asked by sending an e-mail to

What questions can I ask about calculating occupational risks?

  • Benchmarking: the risk of the activities of 1 person in a company, or of different employees within a company can be calculated. This can be compared with the average risk employees run in the Netherlands in similar situations, so that companies can benchmark.
  • Risk inventory and evaluation: the ORCA model can support the preparation of the risk inventory and evaluation by ranking the risks of serious occupational accidents and proposing measures to tackle the risks.
  • Estimation of greatest risks: it is also possible to zoom in on specific activities of an employee, so the greatest risks become clear.  
  • Measures: with ORCA measures can be calculated to reduce the risk. The measures are based on known checklists, safety manuals, procedures, training programs, mandatory training levels and European and Dutch standards and guidelines.
  • Costs and effectiveness of measures: ORCA provides an estimate of the costs and effectiveness of the measure. The model then calculates various combinations of measures and costs and presents them to the user.
  • Injury estimation: ORCA predicts risks of accidents with serious injuries: death, permanent injury and injuries with hospitalization within 24 hours.


Until the end of 2020, you can also calculate work risks yourself using the web application WebORCA. Based on company-specific data about the activities and dangers to which employees are exposed, ORCA indicates the risks per year of serious injury per employee. You can then choose measures that limit the occupational risk and make an optimal assessment of the costs and benefits of those measures.

From the beginning of 2021, WebORCA will no longer be available online, due to  technical reasons.