Human Factors and Ergonomics

The aim of this chapter is to provide a brief understanding of the approaches to driver-vehicle modeling and the impact of driver, vehicle, and roadway characteristics on highway traffic safety. Descriptive behavioral models focus on what the drivers do. These models attempt to describe the entire driving task or some components of it in terms of what the driver does or has to do. The predictive power of such models is very limited because they do not take into account the forces that shape the different behaviors such as driver motivation, skills, capabilities, and limitations in different situations. Despite this severe limitation, these models have provided a strong impetus to driving safety research. The descriptive models can be divided into hierarchical models and control loop models. The hierarchical models describe behavior in terms of a hierarchy of three distinct types of behaviors, each building on the level below it. The lowest level is an operational, control level. At this level, most behaviors are automatic and consist of quick responses to the changing environment. The second level is a tactical, vehicle maneuvering level referring to how traffic situations are mastered. The behaviors are less reflexive and consist of conscious decisions in the driving, such as a decision to change lanes before exiting a highway. The third and highest level is a planning or strategic level, and it consists of long-term decisions such as which route to choose or even whether to drive at all. The second type of descriptive models is the control loop model. These models describe the operation of the driving task in terms of inputs, outputs, and feedback.