Sort of off-topic, but sort of important, at least locally.
The same sort of variable speed limits that the M25 uses in the UK have come to Atlanta. They were installed on the north side of the Atlanta ring road (I-285).
The idea is really great (having ridden in traffic from Gatwick to the M4 more than once). If the traffic velocity is lowered, the probability of a serious disruption is lowered and traffic queues don't grow because there is no longer more traffic coming into it than is going out. So you drive slower, but your trip is shorter.
Is it going to work here in lawless Georgia? No. Too many people already think the speed limit on 285 is 85.
The thing that is different in the UK is the widespread use of automated speed cameras. If you blow through the variable speed limit there you will get a ticket. If you do it here, you most likely won't. (At least as long as you're slower than the police.)