Except it's not. Every lane change in semi-dense and dense traffic is a possible collision; I'd say if you have a car moving in the same direction as you are, a

Except it's not. Every lane change in semi-dense and dense traffic is a possible collision; I'd say if you have a car moving in the same direction as you are, and it's closer than ~50 feet, then it's a non-negligible possibility, other than that you just have nobody to collide with during lane change . We're talking highway speeds, of course, not racetrack