Auto-x, I've gotta disagree with you. You talk about traffic flow like it's a prevailing requirement to conform to. It is not, expecially when it is determined the speed of traffic flow is unsafe.
Posted limits are based on things like roadway geometry and traffic volumes (roadway capacity). If 55 is the posted limit, 70 is not a safer traffic flow - no matter how many people do it. To suggest that it is safer going 70 in those congested conditions with a 55 speed limit is wishful thinking at best. Just wrong-headed IMHO.
Thing of it is, people are sheep & creatures of habit. They see others going over speed, so they push the pedal a little too. Once they've been doing that speed over those roadways for a while, it becomes habit - & a hard one to break, too.
Those folks, by doing the speed limit, did nothing wrong IMHO. The hot-heads & creatures of habit were the ones creating the dangerous situation. Yes, the speed difference is an issue, but the sheep breaking the speed laws are the ones at fault for causing the disparity in speed, not the ones obeying the law.
Frankly, I'd like to see more law enforcement performing rolling road blocks in areas where speeding is a problem. The increased visibility of the LEOs would be welcomed by me as a motorist, and by all of the guys performing the construction work on I-95 where all the speeding is happening here now.