drsteve wrote:
I used to have a high top conversion van that really wiggled behind semis. The worst ones were those with air deflectors on top of the tractor.
Per AARP the 3 second rule applies though road conditions should be taken into consideration.
Safe Following Distance
Maintain at least a three-second following distance to help avoid dangerous situations.
Locate a fixed point ahead. It can be an overpass, a utility pole or a shadow across the road.
When the vehicle ahead of you passes that fixed point, count to yourself, “one thousand one, one thousand two, one thousand three.” If your vehicle passes the same fixed point when you say “one thousand three,” then you have a three-second safe following distance.
If your vehicle arrives at the fixed point before you reach the count of “one thousand three,” you are too close. Slow down slightly and increase the distance between you and the vehicle ahead.
Recheck against a new fixed point after you have increased your distance. You should be able to finish the count of “one thousand one, one thousand two, one thousand three” before you reach that fixed point.
Caution: Do not focus so intently on the fixed point that you fail to observe the total traffic scene.I wish more drivers would be considerate enough to apply this rules when I' driving.