Abstract
Driving a car in the 20th century is complex. Excessive information inside the vehicle and odd road geometry contribute to driver workload. In this chapter, we first define workload and discuss several theoretical issues that underlie workload measurement. We then review several studies that provide insight on how to evaluate driver workload. We focus on secondary-task measures of workload and summarise the state of research in two areas: workload implications of in-vehicle information systems and workload implications of highway design.