Introduction: Driving environment in tunnels is quite different from the ordinary roadway sections, especially the entrance locations, which causes great difficulty in obtaining and interpreting information through fixations and saccades that are relevant to driving safety. Therefore, it is necessary to understand driver's visual behaviors while entering a tunnel so as to take the countermeasures for accident prevention.
Case description: In order to identify the variation of driver's visual features during the process of tunnel entry, 18 participants were recruited to take part in a driving test conducted in real tunnel sections between Qipanguan toll and Jinshui toll of the G5 expressway in Shaanxi, China. During this test, the drivers' fixations, saccades and driving performances were captured for further analysis.
Discussion and evaluation: The test data revealed that the driver's number of fixations, duration of fixations and number of saccades increased gradually at the transition zone. The number of fixations, duration of fixations and number of saccades then drop slightly until the end of the transition zone, and then rise just a little to a stable value after fully adapting to the driving conditions inside the tunnel. Meanwhile, the driver's number of saccades and saccade amplitude value decreased first, and then increased gradually until reaching a relatively stable value inside the tunnel. Additionally, drivers are more cautious at the transition zone, driving conservatively at lower speed, while decreasing their steering wheel angle and minimizing the vehicle's lateral deviation. Specially, novice drivers require a longer transition zone before tunnel entry compared to the experienced ones. Moreover, both novice and experienced drivers take more time to get prepared for tunnel entry while driving at night.
Conclusion: Tunnel entrance section is far more dangerous, so drivers should be educated to get ready ahead for tunnel entry, drive cautiously at lower speed and pay full attention to the traffic flow conditions while driving through the tunnel, especially for the novice drivers in night tasks. Tunnel entrance is suggested to have easily identifiable frame design, with effective traffic signs placed at least 170 m before the entrance and gradually changeable LED lighting along the transition zone. All these suggestions provide insight into potential strategies for reducing and preventing traffic accidents and injuries at the tunnel locations.
Keywords: Driving performance; Novice driver; Safety improvement; Transition zone; Tunnel entrance; Visual feature.