The assessment of mental workload of train dispatchers
Mental workload is a concept that can be interpreted in many different ways. Therefore it is possible that the discussion about mental workload leads to confusion between different parties.
There can be many reasons why people experience a high mental workload and often the discussion about mental workload is mainly based on emotional point of views.
Intergo uses the Integrated Workload Scale (IWS) to assess the subjective mental workload in working conditions. IWS is especially designed for train dispatchers, but is also applicable for other monitoring functions.
For a reliable picture of the subjective mental workload, a representative sample of train dispatchers participates in the IWS study. An IWS observation takes an hour to complete, in which every five minutes the train dispatcher gives his or her score on the Integrated Workload Scale. Also, an observer notes which tasks are carried out by the train signaller during the observation hour.
By putting together the IWS scores and the tasks carried out by the train dispatcher, we can get insight in the subjective mental workload experienced by the train dispatcher. Also, it is possible to see which tasks contribute to a high (or low) mental workload.
The results show that train dispatchers experience a higher mental workload when communicating with third parties (mostly train drivers and engineers). This kind of communication is generally needed when rail traffic is delayed or heavily disturbed or when safety is very important. In these situations one has very little time to inform and understand each other, whereas the interests of the different parties are not always the same.
By combining the results of an IWS study with the objective mental workload – evaluated with the TaskWeighing instrument – it is possible to differentiate objective causes and possible directions for future solutions.
An IWS study has a thermometer function for the present situation and a predictive function for future situations.