I have long contended that most speed limits, at least in my home state of Virginia, are set too low (which is part of why I oppose speed cameras). I’m a big believer in laws and other government regulations saying what they mean and meaning what they say. Speed limits are supposed to be the absolute maximum speed at which a car can travel safely on a road (even if individual vehicles or current conditions require slower travel in some cases). States should set the limits at the maximum safe value (on an open, rural freeway that’s in the area of 75 or 80 miles-per-hour) and then ticket people for breaking that limit by even 1 miles-per-hour. None of this 5-10 miles-per-hour ‘buffer zone’ junk.
One of the fastest rejoinders of the slowpokes is that higher speed limits result in more, and more severe, accidents. I have never felt right about that claim, and more and more studies are starting to show I’m right (though, admittedly, a fair number of studies show the opposite). At minimum, the evidence is very weak for a direct correlation between speed limits and accident volume or severity—and even if there is a correlation, it would likely be mitigated or eliminated if we were more cautious about who we issued driver’s licenses to (e.g., requiring demonstration of solid driving skill before giving license to drive).
In reality, most drivers drive at a reasonably safe speed. Only 10 or 20 percent of drivers, in my humble opinion, drive dangerously fast, and it turns out that many traffic engineers agree! The general rule in-practice (on paper) in the U.S. is that speed limits are to be set at the 85th percentile—meaning the departments of transportation should measure the speed of drivers on the road and set the speed limit high enough that only 15 percent of them would be breaking it. Speed limits in the U.S., however, average about 8-12 miles-per-hour lower than the appropriate 85th percentile speed. Either the DOTs in this country have really, really bad math skills, or they’re not really using the 85th percentile rule.