Evaluating the safety of platooned heavy vehicles: A case study

In the right lane of motorways with trucks' overtaking prohibition is very common the formation of platoons of heavy vehicles. Although this traffic controls strategies can increase the capacity of passing lane, in the right lane may occur increases of rear-end collisions. The purpose of this research was to evaluate the safety of the platooned heavy vehicles by means a closed-form stream model. The case study of the Italian motorway A22 was examined. The sampling of platoons was performed in four observation sections.In the research have been investigated platoons with 2/20 heavy vehicles for each platoon. Many traffic parameters have been evaluated: frequencies of the number of platoons, minimum mean and maximum headways and speeds between heavy vehicles of each platoon, etc. We have found that the percentages of platoons whose vehicles travel with an average headway of less than 3 seconds are in the range 37.1%/66.9%, depending on the motorway section. In addition, it was performed a comparative analysis between the minimum safety spaces "s" and the mean intra-vehicular distances "sa" of platooned heavy vehicles. The results show that the percentages of platoons whose vehicles travel, on average, in safety conditions (δs = s-sa >0) are in the range 32%/43%, depending on the motorway section.