Arrgh, gotta remember to use preview more. Was actually over in Annapolis when it happened (didn't look for or notice the cloud) and just got back home, but heard about it on the radio in the car.
Actually sorta surprised at how few posts this thread has, but on the way back I was wondering how nutty people would be about hoping it was terrorism...I have to say that FR has greatly improved in this respect in the last 6-12 months; had this happened a year ago there would have been a half-dozen posters absolutely insisting it was a terror attack, and that anyone who didn't believe it was a terror attack was an AQ sympathizer (which never quite made any sense, but it did happen quite often.) Actually, I suspect most of those types (can't remember the screennames) have left FR.
Anyway, I fully agree with the previous poster that the reason these trucks explode at major interchanges is that there's more fixed, hard stuff to hit..either going off the road above, or hitting an abutment, instead of simply going off the road.
At least us D.C. area commuters know that this is a regular thing around here. Cars/trucks upside down on any major interstate that happens to between you and your home, just before rush hour in the evening. Traveling 15 miles around here is starting to take 2 hours on a regular basis. It took me 2 1/2 hours to get to the airport (Reagan National) Friday morning due to 1/2 an inch of snow. I-66 closed due to wreck, GW Parkway closed due to wreck...