Maybe temporary in the sense that once the driver is out of the naked area, back to the "forgiving road" where any obstacle that might possibly hinder the flow

Maybe temporary in the sense that once the driver is out of the naked area, back to the "forgiving road" where any obstacle that might possibly hinder the flow of speeding automotives has been removed, the alertness probably falls back to zero again. I don't think it's temporary in the sense that everything goes nicely for the first year and then everyone gets back to normal and accidents increase again. I think that once you're sloshing through flocks of living people with your car and never get a chance to actually clear your way and speed up over 10-20km/h, I suspect that you will always become alert whenever you hit that area. Conversely, walking around in an area where there are 1.5 ton blocks of moving metal without ever getting a chance to actually become absorbed in your thoughts and ignore the environment that you're in all together, you'll certainly feel less secure because you never know what's coming next and from where. Because there's no "known" in the equation and speeds are forcibly slow, people are both more careful and more able to stop their vehicles before anything happens.