Travelling north on I71 north of Columbus, OH, two lanes of traffic at or above limit, everything moving well over the rolling hills. Abruptly, both lanes filled, brakes lights flashing, speed about a fast walk. Happened to end up behind two semis, one in each lane, side by side. No big deal there was vehicles bumper to bumper as far as we could see. Now the amusing part: there were "smarter-than-the-rest-of-us drivers creeping along the shoulders trying to get ahead, but the truckers moved slowly over, blocking the b@#$%. both were doing it and one time they got so far apart, a car started to squeeze between the trucks. When they saw that, they quickly started moving back together just enough to not allow that. I was cheering them and laughing as there is few things that irk me while driving than the folks moving down an empty lane depending on someone to let them in at the bottle neck. This went for 5 miles or more, then suddenly the traffic picked up speed, spread out and there was absolutely no evidence of an accident or construction or heavy traffic on ramps that might have caused this.