Hmmm... OK, not sure if I fit. Is 7 mph "substantial"?
I don't think it works that way. While running thru the clump, the "speeder" is much more alert than simply maintaining a position in the clump. That negates the extra risk, in my experinece.
I don't think the "increased hazard" is all that increased, and may even be decreased because of the level of attention one pays to what one is doing if one is going faster and attempting pbuttes.
You forgot about the guy that is beside a person in a clump, possibly on both sides if a person is running in the center lane of 3 on a large interstate. In a clump, there's someone usually right beside, or slightly ahead, or more often slightly behind where you can forget about 'em easily when making an evasive maneuver to escape someone else's bonehead maneuver. And, you can't control the space directly behind you in a clump, either, and that person will almost certainly be tailgating.
But the person behind him may be stoned or smashed out of his mind, or even just a little high, just enough not to have a good enough reaction time to do the right thing in a bad situation.
Yeah, but in this case it doesn't make any difference about fault. It may be the other guy's fault, but you'll bleed just as red all over the roadway if you don't deal with it effectively. The best way to do that is not to be there, and the best way to do that is not to get caught from behind as a regular thing.
You may be right. When I'm in a clump, most of my thought goes into how to get out of it - not sure what others are thinking.
I don't think those two things are analagous. Going somewhat faster than the general flow isn't like dealing with faster and faster aliens.
Dave Head