Four-way intersection controls and road accidents (including a notation system for intersection conflicts)

It is the conventional wisdom of the road safety movement that the behaviour of drivers can be changed through driver education, public information campaigns, and law enforcement. Unfortunately, there is growing evidence that intensified programmes on these three fronts produce little or no long-term gains in road safety. Real (rather than ideal) people are difficult to reprogramme in a free society. At the same time, there is growing evidence that some road situations are much more accident-prone than others. For example, two-lane highways are much more dangerous than four-lane ones; curves and hills are much more dangerous than straights and levels; and intersections (at which nearly half of all accidents occur) are much more dangerous than non-intersections. These situations represent cases in which the road environment demands more vehicle control than real drivers can always produce.