Driver perspectives of open and tunnel expressways

Urban road tunnels are becoming more extensive due to land scarcity in city areas, and accident rates in these tunnels are comparatively lower than those on open roads. This study examines drivers' perspectives of open and tunnel expressways for 114 active drivers in Singapore using the free association technique. The driver perspectives of open and tunnel expressways were found to be different using t-tests on the frequency of associations to each category, and through multidimensional scaling analysis. Drivers perceive speed, traffic condition, and scenery to be most prevalent for open expressways; while lighting, enforcement, and safety are most prevalent for tunnel expressways. Road qualities important to the driver are identified in this study and the findings are discussed. Analysis of response valence reveals that tunnels are generally perceived less positively as compared to open expressways, and ANOVA found that frequent tunnel users do not perceive tunnel expressways more positively than infrequent users. The response valence is also found to correlate well with the reported quality of experience in each environment. The differences in driver perspectives may help explain differences in driver behaviour. Findings from this study also provide insight to road planners in meeting quality needs of drivers.