Finally, there's an explanation for those wasted hours we spent on the MassPike today asking no one in particular "what the (dirty word) is this (dirty word)?" A team of mathemeticians from the Universities of Exeter, Bristol and Budapest developed a mathematical model revealing that traffic jams are caused by idiots. Okay, not exactly. The real explanation is that unexpected events, such as being cut off, require slowing below a threshold speed for smooth traffic flow. As we've all observed, when the car in front of you brakes suddenly, you need to brake even harder to compensate for your reaction time; this creates a wave that radiates back through traffic. That "backward-traveling-wave" means that because of one driver's inattention, we all pay for it miles behind.
The results of the study really point up the need to drive smoothly. Roads with heavy traffic volume seem to be more prone to traffic jams, too, but that's not necessarily the case. Heavy volume can proceed smoothly if drivers anticipate and avoid sudden actions. In the end, it appears that the main way to fix traffic jams is driver diligence. The low-tech solution is to pay attention when you're behind the wheel, but we've also now got radar-based cruise control that does this for you, so you can continue blithely on your way. It boils down to common sense; be a smooth driver, expect that everyone around you is a moron, and hopefully you won't be slamming on your brakes, causing a domino reaction.