Removing the human driver fundamentally changes what we actually mean by acceptable safety. A simplistic 'safer than human driver' positive risk balance approach must be augmented with additional considerations regarding risk transfer, negligent driving behavior, standards conformance, absence of unreasonable fine-grain risk, ethics and equity concerns. Current standards frameworks and accompanying definitions are likely to be inadequate to ensure safety due to implicit assumptions that are violated when the human driver is removed. A framework relates risk to acceptable safety in a way that is applicable to all autonomous systems.

• Why positive risk balance will not give socially acceptable safety
• Examples of safety issues in the news beyond positive risk balance
• How we need to define acceptable safety for at-scale deployments