Véronique Huth

Intersection Support System for Powered Two-Wheeled Vehicles: Threat Assessment Based on a Receding Horizon Approach

This paper reports a novel intersection support (IS) system for motorcycles developed through the SAFERIDER project (IS). The IS function described is built on a receding horizon approach that is designed for a set of predefined intersection scenarios. In the receding horizon scheme, a nonlinear optimal control problem is repetitively solved in real time, yielding a reference motion plan. The initial value of the longitudinal jerk (control input) of each plan is used as a measure of the correction that the rider has to apply to conform to an optimal-safe maneuver. This technique has the advantage of yielding a homogenous measure of the threat independent of the scenario, and it is directly linked with the control variable that the rider should use to accordingly change the vehicles longitudinal dynamics. Additionally, the receding horizon approach naturally accommodates road geometry and constraint attributes, motorcycle dynamics, rider input, and riding styles. Warning feedback is given to the rider by an appropriate combination of human-machine interface elements, such as the haptic throttle, the vibrating glove, and the visual display. This paper explains the IS concept, discusses the implementation aspects of the proposed receding horizon approach, and presents the results of pilot tests conducted on a top-of-the-range riding simulator.

Drivers' phone use at red traffic lights: a roadside observation study comparing calls and visual-manual interactions.

Phone use while driving has become one of the priority issues in road safety, given that it may lead to decreased situation awareness and deteriorated driving performance. It has been suggested that drivers can regulate their exposure to secondary tasks and seek for compatibility of phone use and driving. Phone use strategies include the choice of driving situations with low demands and interruptions of the interaction when the context changes. Traffic light situations at urban intersections imply both a temptation to use the phone while waiting at the red traffic light and a potential threat due to the incompatibility of phone use and driving when the traffic light turns green. These two situations were targeted in a roadside observation study, with the aim to investigate the existence of a phone use strategy at the red traffic light and to test its effectiveness. N=124 phone users and a corresponding control group of non-users were observed. Strategic phone use behaviour was detected for visual-manual interactions, which are more likely to be initiated at the red traffic light and tend to be stopped before the vehicle moves off, while calls are less likely to be limited to the red traffic light situation. As an indicator of impaired situation awareness, delayed start was associated to phone use and in particular to visual-manual interactions, whether phone use was interrupted before moving off or not. Traffic light situations do not seem to allow effective application of phone use strategies, although drivers attempt to do so for the most demanding phone use mode. The underlying factors of phone use need to be studied so as to reduce the temptation of phone use and facilitate exposure regulation strategies.

Predicting the acceptance of advanced rider assistance systems

The strong prevalence of human error as a crash causation factor in motorcycle accidents calls for countermeasures that help tackling this issue. Advanced rider assistance systems pursue this goal, providing the riders with support and thus contributing to the prevention of crashes. However, the systems can only enhance riding safety if the riders use them. For this reason, acceptance is a decisive aspect to be considered in the development process of such systems. In order to be able to improve behavioural acceptance, the factors that influence the intention to use the system need to be identified. This paper examines the particularities of motorcycle riding and the characteristics of this user group that should be considered when predicting the acceptance of advanced rider assistance systems. Founded on theories predicting behavioural intention, the acceptance of technologies and the acceptance of driver support systems, a model on the acceptance of advanced rider assistance systems is proposed, including the perceived safety when riding without support, the interface design and the social norm as determinants of the usage intention. Since actual usage cannot be measured in the development stage of the systems, the willingness to have the system installed on the own motorcycle and the willingness to pay for the system are analyzed, constituting relevant conditions that allow for actual usage at a later stage. Its validation with the results from user tests on four advanced rider assistance systems allows confirming the social norm and the interface design as powerful predictors of the acceptance of ARAS, while the extent of perceived safety when riding without support did not have any predictive value in the present study.