When I was stationed in Maryland in the early 1980s, an elderly man made it his mission to make sure that people obeyed the speed limit on the Beltway. He would set his cruise control for 55 mph and drive in the left lane.
The Maryland State Police got notice of this and instead of ticketing the guy for impeding traffic, they adopted his method.
A line of Maryland State Police cars would drive the Beltway, three or four abreast, blocking all the lanes, at 55 mph. This is the normal reaction of bureaucracy. Rules must be enforced. Whether or not they make sense and whether or not they achieve their goal is immaterial. In this case, while it did slow people down, it most likely caused other problems with people trying to avoid it. It was finally quietly dropped.
Neal Boortz has a link to a video made by some Georgia State University students that did the same thing in Atlanta. The results were much the same.
“Rolling Roadblocks” seem to be a popular method with local governments to slow traffic down and creating congestion. Then the politicians can spend millions on “studies” and commissions to figure out what to do about it.
How about just letting the traffic flow?