This happened in Atlanta several years ago. A coworker and I decided to play hockey and go to a rare day game at Turner Field on a weekday.
We were rolling down I-85 towards the stadium in the middle of 5 southbound lanes, doing about 10 or more miles per hour over the limit. (That's fairly common in Atlanta. ) We were in some traffic, following at a reasonable distance from the car in front of us. The two lanes to our left were empty for a good distance behind us and ahead of us. The two lanes to our right were moving briskly as well with traffic merging on from Georgia 400. In the US, we drive faster in the left lanes, as we pass on the left.
As we passed 400, three very large SUVs and pickup trucks were merging in a very tight group. They moved left two lanes behind me and rapidly caught up. I was not concerned as the two lanes to the left were empty, and this is where people running 20 mph over the posted limit get to as soon as they can.
However, they did not move there, even though they could. Instead, the lead pickup got very close to my bumper, and the other two got in close to the one in front of them. After a minute or so, I figured on moving left 1 lane, and letting them tailgate the car in front of me.
As I put on my left turn signal, I saw the car in front of me move left as well, revealing the aluminum extension ladder lying across the middle of 5 lanes. I didn't dawdle in moving left.
The lead pickup saw my signal and motion, as well as the car in front of me moving into the second lane from the left, and floored the accelerator, making a clearly audible roar of a Dodge diesel developing maximum acceleration. Instantly following suit, the two closely trailing vehicles added their mighty engines' roars to the cacophony.
As the behemoth pickup pulled even with me at 80 or so, he finally saw the ladder and slammed on the brakes, as I continued to the leftmost lane, in case he swerved.
He did not. The first sight was the ladder folding up on either side of the pickup as the front wheels hit it, scraping down each side of the truck. This was followed by two rear end collisions as the trailing vehicles hit the first pickup and each other.
And that was that. I still don't know why they didn't go to either of the empty faster lanes.