With unspoken assumptions about how much an increase is needed things become arbitrary.
IMO, if allowing self driving cars on highways costs less than 100k per mile it’s a rather trivial expensive at 16 Billion in the US. Extending that to every road would be much harder to justify. Similarly, developing something like a set of more clear hand gestures for directing traffic would not be a major issue.
Honestly, the need for expensive changes seems unlikely, though some changes such as paint choices for lane markings would probably increase safety or efficiency.
IMO, if allowing self driving cars on highways costs less than 100k per mile it’s a rather trivial expensive at 16 Billion in the US. Extending that to every road would be much harder to justify. Similarly, developing something like a set of more clear hand gestures for directing traffic would not be a major issue.
Honestly, the need for expensive changes seems unlikely, though some changes such as paint choices for lane markings would probably increase safety or efficiency.