2.1 The driving task
Consideration of the requirements of the driving task is fundamental to assessing a person’s medical fitness to drive.
Driving is a complex instrumental activity of daily living. It involves a complex and rapidly repeating cycle that requires a level of skill and the ability to interact with both the vehicle and the external environment at the same time (refer to Figure 1).
The demands of the driving task can vary considerably depending on a range of factors including those relating to the driver, the vehicle, the purpose of the driving task and the road environment (Box 1).
Information about the road environment is obtained via the visual and auditory senses. The information is operated on by many cognitive processes including short- and long-term memory and judgement, which leads to decisions being made about driving. Decisions are put into effect via the musculoskeletal system, which acts on the steering, gears and brakes to alter the vehicle in relation to the road. This repeating sequence depends on:
- Sensory input
- visuospatial perception
- Cognitive function
- attention and concentration
- decision making
- reaction time
- Motor function
- muscle power
Given these requirements, it follows that many body systems need to be functional in order to ensure safe and timely execution of the skills required for driving. The driver’s sensory, motor and cognitive skills may require detailed assessment to determine the potential impact on driving.
Box 1: Factors affecting driving
Driving tasks occur within a dynamic system influenced by complex driver, vehicle, task, organisational and external road environment factors including:
For commercial or heavy vehicle drivers there are a range of additional factors including: