They are a massive safety feature on highways for sure and used significantly throughout the nation - which is why i've always wondered why we dont use them more. I feel like they are probably one of the most efficient driver alert/behavior modification systems out there. Efficient by cost to install, maintain, not as divisive as speed bumps, dont impact certain vehicles like snow plows or other vehicles, and it wont damage your car if you accidentally dont see it or take it too fast (we've all been there).