The impact of visual attractions on drivers' visual performance and mental workload in highway tunnel access zones

The visual attractions present in the access zones of highway tunnels can exert a detrimental effect on drivers' visual performance and mental workload, thereby posing a significant risk to driving safety. This study aims to evaluate the impact of these eye-catching elements on driving safety performance by comparing and analyzing the influence of various visual attraction conditions in tunnel access zones on both the objective visual performance and subjective mental workload assessments of novice and experienced drivers. Four distinct visual attraction scenarios were selected for implementation in the access zones of highway tunnels: baseline, landscapeinspired architecture, informational tip slogans, and commercial billboards. Naturalistic driving experiments were conducted, supplemented by subjective mental workload measurements, to analyze a range of factors, including drivers' first fixation duration (FFD), mean fixation duration (MFD), distance from tunnel portal when first fixation occurs at visual attraction (DTP), number of fixations (NOF), pupil diameter (PD), and visual sample entropy (SampEn). Subjective mental workload was assessed using the NASA-TLX scale. The results revealed that visual attractions within tunnel access zones significantly affected drivers' objective visual performance and subjective mental workload evaluations. Different visual attractions exerted varied effects on visual attention, stability, cognitive workload, and subjective mental workload. Specifically, billboards were found to rapidly capture drivers' attention, leading to unstable visual performance. Informational tip slogans demanded greater attention and cognitive effort, resulting in increased cognitive workload. Furthermore, novice drivers demonstrated poorer visual performance, stability, and higher workload compared to their experienced counterparts. This research highlights the intricate relationship between visual attractions and their impact on drivers' visual performance and mental workload, emphasizing the need for targeted interventions and enhancements in visual strategies particularly tailored for novice drivers. The findings contribute to the domain of transportation psychology and offer practical implications for improving the safety and efficiency of tunnel access zones through evidence-based design strategies. Ultimately, the insights gained from this study can guide the design of visual attractions in highway tunnel access zones to optimize drivers' visual performance and mitigate mental workload.