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The more common example experienced by most of us is the all too frequent situation of being stuck in traffic for long periods only to find that the cause of the disruption was an automobile accident on the other side of the median. There’s no reason for traffic on your side to be delayed except for the rubberneckers ahead of you.

Actually, no, this is a myth. There is another reason for this phenomena. What happens is that, first, an accident causes a slowdown over a period of time. After that, however, it is not rubberneckers causing delays, but rather that temporary delays have an inherent "stickiness" over time. Experiments showed that random slowdowns, regardless of cause, will continue long after the initial cause has subsided, and display the exact same pattern as a wreck-induced slowdown. Computer modeling showed that it was actually that the slowdown-speedup pattern wasn't efficient, and each subsequent car will retain part of the delay, so to speak. The delay therefore takes a number of iterations before it finally is removed from the system.

Scientific American did a much better job explaining this a couple of decades ago (back when they weren't just a political rag). Similarly, there was a chronic mystery slowdown on 95 south of DC. For the longest time, people couldn't figure out what was causing it, and blamed "rubberneckers" (invariably, there will be at least one car on the side of the road). What researchers found, however, was that some trucks were having difficulty with the hills, and this created a similar pattern where only a handful of trucks laboring caused delays in the same spot, delays which lasted hours after the trucks were gone.