Effect evaluation of traffic guidance in urban underground road diverging and merging areas: A simulator study

Traffic accidents occur frequently in urban underground road diverging and merging areas due to the limited vision and complex traffic. Well-designed traffic visual guidance is one of the effective measures to alleviate the traffic safety problems in the diverging and merging areas of urban underground roads. In this study, four different integrated traffic guidance schemes (including signs, marking lines and sidewall guidance) were proposed and their effects on drivers' behaviour were investigated through driving simulator experiments and questionnaire survey. To investigate the influence of different schemes, eight variables about driving behaviour and guidance efficiency were assessed for analysis. Finally, a fuzzy comprehensive evaluation model based on analytic hierarchy process (FCE + AHP) was constructed to evaluate the effect of guidance schemes. Vehicle running state, driver operation behaviour and guidance efficiency were mainly considered. The guidance evaluation results obtained by the model were consistent with the conclusions of the driver subjective questionnaire. The results show that reasonable setting of white dotted lines and colour guidance can help drivers find exits quickly and improve driving stability. However, excessive combination of traffic guidance leads to information overload and produces the opposite effect. This study can provide a generic framework for the design and evaluation of traffic guidance facilities of urban underground roads.