There used to be a saying that road designs were a function of the road, the vehicle and the driver. It now appears that there are different types of driver, and some standards are appearing which suggest different values for design when the driver type is an “older driver” (ref. 2439) or a member of the “aging population” (ref.2441). It appears the USA document was first published in 1998.
Ref. 2441 USA, Handbook for designing roadways for the aging population 2014 , FHWA, 2014
Ref. 2439 Austroads, Road safety environment and design for older drivers, 2000