Effects of highway tunnel zonal characteristics and geometric design on traffic safety

Traffic safety issues in highway tunnel sections are well known, while how tunnel alignment design and zonal characteristics affect driver behaviour and traffic safety remains unclear. To comprehensively investigate zonal traffic safety in highway tunnels, alignment and crash data of eight tunnels were obtained. The tunnels were virtually reconstructed using driving simulation equipment, and controlled experiments were conducted. Based on tunnel length, the tunnels were classified into different types, and each was divided into zones using a seven-zone method. Crash data and driving behaviour characteristics were analysed for each zone, with driving behaviour examined through repeated-measures one-way analysis of variance. Spearman correlation analysis was employed to identify relationships between alignment design indicators and driving behaviour. Significant indicators were then incorporated into a mixed linear regression model to explore statistical relationships. Results revealed that access zone, entrance zone and mid-zone are high-risk areas, where drivers’ speed and lane departure exhibit distinct zonal characteristics. The regression analysis indicated that both horizontal and vertical alignment designs significantly influence speed, whereas their impact on lane departure is less pronounced. By analysing zonal traffic safety conditions and their contributing factors, this study provides valuable scientific insights for tunnel alignment safety design and traffic management.