SIMULATION AND SAFETY ASSESSMENT OF MIXED TRAFFIC FLOW WITH HIGHLY AUTOMATED VEHICLES IN PORT AREAS

Abstract

The growing use of automated vehicles in port logistics demands reliable methods for assessing traffic safety in mixed environments where automated and human-driven vehicles interact. This study evaluates the safety performance of mixed traffic flows involving automated guided vehicles operating within a port terminal con-nected to an external road network. A microscopic traffic simulation model was developed to replicate port operations, including internal transport and interac-tions with external container trucks. A factorial experimental design was used to analyze six scenarios with varying automation levels, from fully human-driven to fully automated traffic. Trajectory data were analyzed using surrogate safety indi-cators-Time-to-Collision (TTC) and Post-Encroachment Time (PET)-to quantify traf-fic conflicts. Results show a significant reduction in total conflicts as automation increases, particularly rear-end collisions. However, mean TTC and PET values also decline, indicating closer but more stable vehicle interactions enabled by automat-ed systems. This reveals a limitation in applying traditional surrogate safety thresh-olds, originally calibrated for human driving behavior, to automated environments. The findings highlight the need to adapt safety assessment methodologies to ac-count for the operational characteristics of automated vehicles, including tighter temporal gaps and more consistent behavior in mixed-traffic port settings.