Comprehensive Evaluation and Classification of Interchange Diagrammatic Guide Signs’ Complexity

The effectiveness of interchange diagrammatic guide signs has significant meaning in traffic safety and driver’s understanding. This paper presented a comprehensive evaluation and classification of interchange diagrammatic guide signs’ complexity. The effectiveness of interchange diagrammatic guide signs relies on how well road users can understand those diagrams. This study tested 37 types of diagrams on the visual recognition complexity degree in three levels, general level, partial level, and detailed level, and finally seven indexes are selected to evaluation and classification of interchange diagrammatic guide signs’ complexity. These indexes can be used to conduct quantitative evaluation and classification. And the result of diagram complexity range is between −1.366 and 2.046, which have a correlation with graph cognition complexity, including perspective of distribution, diagram character, essential element expression manner, and utilization degree, and K-means clustering method was used in the analysis. Based on the presented method, 37 types of diagrams are separated into three categories according to their complexity score: low complexity, medium complexity, and high complexity. This study not only presents a theoretical approach for quantitative evaluation of guide signs’ complexity and effectiveness but also can be a reference for traffic sign design and application.