Drivers’ Behavior at Unsignalized Intersections: An Empirical Analysis and Derivation of Requirements for the European Regulation 1426/2022 Concerning the Type-Approval of Automated Driving Systems

Automated driving systems (ADSs) navigating intersections, on top of avoiding accidents, should respect the safety distances accepted by human drivers, especially in case they lack the right of way in an unsignalized intersection. Failing to properly handle these types of situations can result on the one side in a high perceived risk by the approaching human drivers, who could then harshly react and generate risks to themselves and other road users, and, on the other side, in reducing the throughput of the intersection with possible aggressive and risky maneuvers by the human drivers following the ADS. In order to support defining an acceptable separation between an ADS and other road users in the case of crossing and merging with privileged traffic at unsignalized intersections, the present work analyzes the actual minimum separation accepted by human drivers in these conditions. Real-world maneuvers have been extracted from two large datasets concerning urban and sub-urban unsignalized intersections. Results show that the average level of accepted risk registered in the two datasets is comparable. Important differences are found only for the most aggressive or conservative drivers. The results of the present study have been used to define the requirements for intersection merging and crossing introduced by the European Regulation 1426/2022, on the type-approval of SAE J3016 Level 4 ADS.