Driving behaviour

The driving behaviour impact area addresses the driving dynamics of single vehicles with and without CCAM system by examining their longitudinal and lateral movements and their interaction with the environment and other road users.

Driving behaviour evaluation focuses on the driving dynamics of the vehicle under study (the ego vehicle). These dynamics are the product of how the vehicle and driver interact with the environment and other road users. In other words, driving behaviour evaluation observes how a vehicle moves on the road within the traffic flow.

An automated driving system (ADS) may partly or completely replace the human driver. The vehicle may be driverless, or, when partially substituted, the human driver may take or be given back control of the vehicle. In this chapter, “driver” may refer either to a human or to the ADS; in other words, the entity responsible for deciding the vehicle’s longitudinal and lateral movements. In manual vehicles it is a human, and in automated vehicles operating in automated mode it is the ADS.

Driving behaviour can be observed in the real world in field experiments and, to some extent, with driving simulators and microscopic traffic simulations. Virtual methods allow for analysis of driving scenarios that are difficult to test in real-world conditions, such as safety-critical situations, platoons of automated vehicles, or near-capacity traffic flows. It is essential, however, to validate the extent to which the simulation accurately reflects the vehicle’s real behaviour.

Often, the driving behaviour of automated vehicles is compared to that of fully human-driven vehicles. Additional comparisons can be made between the driving behaviours in different environments, including when entering and exiting the operational design domain, under varying sensor configurations, or with and without vehicle-to-everything communication. Finally, the evaluation can include both how the automated vehicle affects nearby road users and how the driving behaviour of other road users influences that of the automated vehicle.

Within the scope of this chapter are:

• Ego vehicle and how it drives through traffic: vehicle trajectories, speed and acceleration, lateral movement including lane change, position in lane, following behaviour, interaction with other road users and objects nearby.
• Frequency of and duration spent in specific driving scenarios: how often and for how long the automated vehicle engages in certain driving scenarios. For example, whether the vehicle makes fewer lane changes, more cut-ins occur, or the vehicle spends more time following a lead vehicle.

Driving behaviour is often described as the result of interactions between the driver, the vehicle, and the environment.

Main components of the driving behaviour impact area.