Well, I think that's part of it right away.
Roads aren't dangerous, and therefore the use of the word 'safer' shouldn't really apply to any of them! When's the last time you were on a road and part of it jumped up and hit you?
Engineering measures to reduce road traffic collisions (I prefer the term crashes - but I can never say accidents!), like guard rails, and sign posts which collapse when hit could, expensively go to the nth degree.
It is invariably the motorist that is the weak link so education of the driver would be the best way to make roads 'safer'.
I would like to see compulsory retesting for anyone who is banned from driving - especially those that have injured or killed another person. I am sickened that someone can kill someone with their car and essentially get off with a temporary ban (no need for a retest - simply wait out the ban), a fine and either a short stay at her majesty's pleasure or a community thingy.