A method of determining data indicative of an individual driver workload is disclosed. The method involves obtaining a generic driver workload parameter, the generic driver workload data being based on data indicative of the behavior of multiple drivers when performing a maneuver at a node or traversing a set of one or more segments of an electronic map. An individual modifier representative of the behavior of an individual driver is generated and used to determine an individual driver workload parameter indicative of the workload of the individual driver when performing the maneuver at a node or traversing the one or more segments of an electronic map based on the generic driver workload data for performing the maneuver at the node or traversing the one or more segments of the electronic map.