[manicdee]

Lower speed limits will not reduce the number of deaths, unless all traffic is reduced to 40km/h or less.

Inattentive drivers, confusing road signage, insufficient separation of pedestrians and cars, drivers not following established rules and guidelines: these are the contributing factors which can be addressed to reduce road fatalities with greater reduction of fatalities than simply reducing speed limits.

Autonomous cars won't speed for thrills, they won't cut lanes or run red lights. They will be far safer, if more annoying, than most drivers: just like the more conservative human drivers we already have.