Explaining the dynamics and identifying potential risks of hazardous materials truck movements

The growth of global economy and deep specialization of industries have jointly led to a steady increase in demand for hazardous materials (HazMat) such as liquid hydrogen and nitrogen, resulting in high frequency of HazMat truck movements. Identifying the activities and understanding the characteristics of such movements are critical to reducing their negative environmental impacts. In this study, we propose a data-driven approach for extracting trips from GPS data and analyze the travel characteristics of HazMat trucks. Three dwell time thresholds are determined for distinguishing HazMat truck stop activities corresponding to 1 min, 20 min, and 288 min, respectively. Results show the spatial network of HazMat movement is subject to locations of both suppliers such as chemical industries and customers like medical offices. The spatial distribution of the trips uncovers the mobility patterns of HazMat trucks. While long-distance trips that handles the intercity shipment of HazMat generate environmental risks at the regional level, trips of less than 20 km impose potential hazards on local streets even in central areas. The risk maps for different types of HazMat transportation further reveal the unique spatial risk hotspot distributions of each category, providing valuable insights for precise risk management and policy development. The approach proposed can help characterize the mobility patterns and assess potential risks of HazMat movements, thereby promoting sustainable urban freight transportation.