How Does Driver Takeover Worsen in a Sudden System Failure of Conditionally Automated Driving?

Conditionally automated driving is getting extensively attractive to us. Transition from a system to a driver in conditionally automated driving is necessary once the vehicle encounters the situation in which the system cannot work further. There are two types of takeover situations. One is system failure, in which the system is deactivated immediately with issuing a request to intervene (RTI). The other is exit from the operational design domain (ODD), in which the system is disengaged several seconds after the issue of RTI. In this study, a simulator experiment of 32 participants was conducted. The driver takeover performance in system failure condition was compared with that in the ODD exit condition. Results revealed that drivers responded significantly faster in the system failure condition. There was no significant difference of longitudinal takeover performance between the two types of limitations. However, the drivers generally performed worse lateral takeover performance in the system failure conditions.