Naturalistic Driving Study in China Showed In-Vehicle Navigation Enabled Drivers to Focus More on Driving Information Interaction Before Entering Tunnels, Increasing Eye Fixations by Up to 15.2 Percent.
Study Evaluating the Safety Benefits of In-Vehicle Navigation Systems at Seven Tunnel Entrances in Guangdong Province, China.
Guangdong Province
Effects of In-Vehicle Navigation on Perceptual Responses and Driving Behaviours of Drivers at Tunnel Entrances: A Naturalistic Driving Study
Summary Information
Perception and reaction behaviors of drivers at tunnel entrances could vary extensively, which could lead to accidents. This study investigated the effects of in-vehicle navigation on perceptual responses and driving behaviors. Naturalistic driving experiments were conducted with 20 drivers at seven tunnels along an 80.5 kilometer (about 50 miles) stretch of the No. G55 mountainous freeway in Guangdong Province, China. A comparative analysis was performed under a control condition and in-vehicle navigation condition, considering an area extending 200 meter outside the tunnel portal to 200 meter inside the tunnel portal, which was divided into four zones.
METHODOLOGY
In this study, naturalistic driving experiments compared the in-vehicle navigation condition, using voice warnings, to the control condition, normal driving without navigation. The in-vehicle navigation condition was set up so that, at one kilometer (0.62 mile) before the tunnel portal, the smartphone would send the voice warning message alerting the driver about the approaching tunnel. The interval of messages was five seconds, and the message was repeated five times for each tunnel under the in-vehicle navigation condition. For each experiment zone, two types of perceptual responses (visual responses and psychological responses) and driving behaviors were analyzed using six indicators: number of visual fixations of a driver in a specific zone, average duration of fixations, time interval between continuous waves of heartbeats of the driver, Skin Conductance Response (SCR) as an indicator of psychological stimulation, speed difference in zones, and maximum deceleration.
FINDINGS
- The results showed a 15.2 percent increase in drivers' average number of eye fixations before tunnels, indicating that in-vehicle navigation improved attention to driving information.
- The results also indicated up to 9.6 percent increase in the duration of the interval between driver heartbeats with in-vehicle navigation guidance compared to the control group, implying reduced mental workload due to the in-vehicle guidance technology.
- The study estimated that the total number of SCR decreased from 132 under the control condition to 120 under the in-vehicle navigation condition, a 9.1 percent reduction, indicating that in-vehicle navigation could decrease the driving workload while in the tunnel by limiting psychological stimulation.
