• Driver warning systems actively warn the driver of a potential danger, e.g. lane departure warning, blind spot warning, and forward collision warning (FCW) systems [12]. This
Figure 1. Total number of road accidents and fatalities per total distance travelled, normalised on 1965 data for the EU [1]. In addition, the graph shows when passive safety systems (which reduce fatalities in case of an accident) and active safety systems (which assist in avoiding an accident) have been introduced, as well as the expected safety potential of ADASs [8–10].
warning then allows the driver to take appropriate corrective actions in order to mitigate or completely avoid the event.
• Intervening systems provide active support to the driver, e.g. an adaptive cruise control (ACC) system [13]. ACC is a comfort system that maintains a set cruise control velocity, unless an environment sensor detects a slower vehicle ahead. The ACC then controls the vehicle to follow the slower vehicle at a safe distance, see figure 2. ACC is intended for speeds above 30km/h, but is currently being extended to a stop-and-go application for automated longitudinal control in low-speed complex environments, such as traffic jams and urban areas [14].
• Integrated passive and active safety systems. In addition to passive safety systems that are activated during the crash, a pre-crash system can mitigate the crash severity by deploying active and passive safety measures before a collision occurs [15]. Pre-crash safety measures, such as brake assist and seat belt pre-tensioners, have recently been introduced on the market [16].
• Fully automated systems are the next step beyond driver assistance, and operate without a human driver in the control loop. Automated highway systems, using fully automated passenger cars, are expected to significantly benefit traffic safety and throughput, but are not considered for short-term introduction [17].
According to several surveys ADASs can prevent up to 40% of traffic accidents, depending on the type of ADAS and the type of accident scenario [8–10]. Despite this safety potential, market penetration of ADASs has gone slow. Main challenges in this respect are customer acceptance and understanding of the added value, liability exposure, and regulatory issues [6, 18]. Drivers also expect an ADAS to meet high requirements in terms of (subjective) performance, reliability (low rate of false alarms), and safety (low rate of missed detections). Therefore, the ADAS must be tested for the wide variety of complex traffic situations that the system should be able to recognise and handle [19]. Unfortunately, exhaustive testing of an ADAS prototype is usually impossible due to constraints in costs and time-to-market. Not only the design, but especially the validation of ADASs, thus requires a growing effort in the development process. To address these issues, efficient