Tarmac / asphalt only has a service life of 26 years. (And resurfacing after 13 years.) So within the sort of timeframes governments are already used to for inf

Tarmac / asphalt only has a service life of 26 years. (And resurfacing after 13 years.) So within the sort of timeframes governments are already used to for infrastructure construction (eg, HS2 is due for completion in 2033), almost all the road surfaces will already have been replaced anyway. The trick is to do it economically. Do some of the major trucking routes first, as well as common city roads. ie, automate trucks and busses first. Especially as to begin with you'd probably want to exclude bicycles, horses, etc, so that means not doing every road. But that's just speculation.