Effects of Intelligent Warning Systems on Drivers' Steering Wheel Angle in Fog Situations
Authors: Paula Larocca Ana , Calsavara Felipe 
Published: June 2023

Visibility is essential for the driving task and its reduction due to fog influences drivers' behavior. A solution to reduce accidents in fog is adopting intelligent transport systems that notify the driver in advance about the road conditions, allowing the driver to adapt his driving behavior. Intelligent Transport Systems (ITS) based on connected vehicle communication have increasingly been incorporated into vehicles to help overcome the abovementioned problem. They notify drivers of potentially dangerous road conditions, such as fog, to adapt their driving behavior better. Few academic studies link driver behavior with their safety in low visibility situations, leaving gaps in understanding a driver's directional change strategy in low visibility situations and the relationships due to the use of in-vehicle warning systems. In order to achieve the objectives of the work, this study proposes a controlled experiment with real drivers in a simulated driving environment. Through driving simulators, drivers can be repeatedly confronted in different circumstances, including specific weather conditions, without risk to life and with reduced costs, which is a tremendous advantage over field tests. This work investigated the effects of the presence or absence of fog on the steering wheel angle of drivers. A driving simulator was used to recreate real scenarios of a Brazilian highway with a high incidence of fog, showing the geometric and meteorological conditions of the site. The physical structure of the simulator is composed of a driving cockpit with a car seat, steering wheel with force feedback, gearshift lever and pedalboard with accelerator, brake and clutch pedals. The cockpit station also allows for height and distance adjustments between the seat and the steering wheel. The simulated environment was projected onto a 1.40 x 0.80 m flat panel by a DepthQ HDs3D2 projector with a resolution of 1080p and a refresh rate of 60 Hz. The projected field of view is 120º and 50º in horizontal and vertical views, respectively. For eye tracking, a device specifically designed for this purpose was attached to the simulator: Smart Eye, model Pro 5.10® (SE). A frame-by-frame analysis was performed on each video with gaze position superimposed on the field of view to identify participants' attentional allocation on the HUD when the fog warning was displayed. To investigate how often and when participants inspected the HUD, the fog alert region on the HUD was defined as a region of interest (ROI), as seen on the right of Figure 1 and only those participants whose fixation at the time of the warning was included in this area were part of the sample of this research. Rearview mirrors are also projected into the dashboard, as well as a Head-Up Display (HUD) to show fog warning messages and the speedometer. Speakers with 32 watts RMS of power were used to reproduce sounds similar to the vehicle's engine and the wind, in order to improve immersion. The simulated rural road is a 5 km stretch of an essential Brazilian highway. The stretch is in a mountainous region with a high incidence of fog and many curves in its geometry. The highway administrator provided the geometric design of the section necessary for the virtual modeling, the VDM (Average Daily Volume), as well as the location, type, and severity of accidents that occurred in recent years. The simulation period was the month of June, and the time was set to 6 am, which, according to data from the Federal Highway Police (DPRF, 2022), is the most frequent period of accidents with foggy weather conditions. The results agree with those found by Abdel-Aty et al. (2011), who observed in the state of Florida (USA) that fog was the leading cause of collisions in rural areas during the winter months and in the early morning hours. However, the results of the most common type of collision analyzed in Brazil differ from those found by Abdel-Aty et al. (2011). In Brazil, between 2017 and 2021, the fog's most common type of collision was “Exit from car bed” (23%) and involved only one vehicleIn the foggy scenario, the driver adjusted the steering wheel angle more times than in the no-fog scenario. This text, in addition to presenting detailed analyses of accidents that occurred under foggy weather conditions, also sought to clarify drivers' behavior when driving in fog with a warning system built into the vehicle.In Brazil, unlike what is found in the USA, the most common type of accident to happen is "Exit from a cart" and it does not involve multiple vehicles.