A critique of the SAE conditional driving automation definition, and analyses of options for improvement

The Society of Automotive Engineers defines five levels of driving automation (LoDA) (plus a “no-automation” level 0). Among them, the third level, called “conditional driving automation,” here denoted LoDA 3, performs the complete dynamic driving task (DDT) within a limited operational domain. Although the driver is free from any driving task while the automation is engaged, she is expected to be receptive to an automation-issued request to intervene (RTI) and is also expected to perform DDT fallback in a timely manner. This paper gives a method to derive an optimal design for RTI and proves that LoDA 3 coupled with the optimal RTI should never be simply called “conditional driving automation.” This means that the definition of LoDA 3 is not complete and that at least one important level is missing in the list for LoDAs. This paper provides two ways to resolve the problem.