Lena Nilsson

The Effect of Road Transport Telematics

The introduction of road transport telematics (ITS, the most commonly used abbreviation for the topic, standing for “Intelligent Transport Systems”) may turn out to be the greatest and most comprehensive transformation of road transportation since the invention of the combustion engine. General objectives of ITS are to increase transport efficiency, to improve traffic safety and to reduce traffic related pollution (Franzen, 1993; Perrett and Stevens, 1996). The way ITS will influence future traffic, and how it will affect driving behavior is only to a certain extent predictable from current knowledge, therefore much research has been devoted to this topic during last decade. Obviously, the addition of advanced technology to the traditional driver-vehicle-environment interaction will increase the complexity of the road traffic system (Rumar, 1990a). Presumably also the task of driving will gradually change as the implementation of ITS functions proceeds. One possible development is that electronic communication between infrastructure components and vehicle components will replace several current driver functions, for example, detection of relevant traffic and roadside information and speed choice recommendations. Also certain parts of the vehicle-to-vehicle interaction, for example, distance keeping, may change from being performed manually to being performed by more or less automatic ITS.

Drivers’ Reliance on Lane-Keeping Assistance Systems as a Function of the Level of Assistance

ZusammenfassungWir untersuchten die Bereitschaft von Fahrern, die Kontrolle an ein Spurhaltesystem in Abhängigkeit vom Automatisierungsgrad abzugeben. 45 Probanden fuhren in einem Fahrsimulator (VTI, Schweden) und wurden durch ein Spurhaltesystem (hoher Assistenzgrad), ein Spurverlassenswarnsystem (geringe Assistenz) oder durch kein System unterstützt. Als Indikator für das Ausmaß, in dem sich Fahrer auf das System verließen, wurde ihre Bereitschaft verwendet, Aufmerksamkeit einer Zweitaufgabe zuzuwenden. Wir fanden, dass sich die Fahrer erheblich im Vertrauen an ein System unterschieden. Der jeweilige Fahrstil spielt dabei eine wichtige Rolle. Die Fahrer vertrauten um so mehr dem Spurhaltesystem, je ängstlicher und unsicherer sie sich einschätzten. Eine wesentliche Schlussfolgerung ist, dass der selbst eingeschätzte Fahrstil ein wesentlicher Faktor ist um vorherzusagen, in welchem Ausmaß Fahrer Systemen mit unterschiedlichen Automatisierungsstufen vertrauen. Im Design von Systemen sollte darauf geachtet werden, dass Systemgrenzen sichtbar bleiben, um „Übervertrauen“ zu vermeiden.AbstractWe investigated drivers’ willingness to allocate control to a lane-keeping assistance system as a function of the level of assistance. Operators were found to increasingly rely on automation with higher reliability. We assume a similar effect of the level of assistance on reliance resulting from operators’ perception of a reduced need to engage in automation controlled processes. Forty five participants drove in a moving base driving simulator wiTheither a lane-keeping control (LKC) system (high level of assistance), a lane departure warning (LDW) system (low level of assistance) or without lane-keeping assistance. The allocation of visual attention away from the road scene towards an in-vehicle display of a secondary task was used as an indicator of drivers’ reliance on the systems. We found that drivers diff ered significantly in their reliance on and trust in the LKC system. Individual driver characteristics, i.e., self reported driving style, had a significant influence on drivers’ trust. Drivers placed more trust in the LKC system the more they regarded themselves as anxious and unconfident drivers, and more trust in the LDW system the more they regarded themselves as unobservant drivers. A major conclusion is that self-reported driving style is an important factor to predict if drivers are prone to place their trust in, and rely on, higher level driving assistance. Study results call for transparency in the design of driver assistance systems to avoid false expectations regarding system capabilities. Functional system limits should be made easily identifiable for drivers in order to reduce the likelihood of overreliance.

End-users' Acceptance and Use of Adaptive Cruise Control Systems

An online survey was distributed to end-users of adaptive cruise control (ACC). In total 90 drivers answered the questionnaire, which covered e.g. ACC usage and how such use affects driver behaviour. According the responses: the ACC is used primarily on roads with higher speed limits; the end-users trust the system even though it has some functional limitations; they have a very positive attitude towards the system; and positive effects on comfort and safety are observed including reduced inclination to overtake and increased compliance with speed regulations.