The volume of cars is a scale factor that determines the impact of traffic causing behaviors and conditions for free flowing highways (no traffic lights, stop signs, etc.). Following too closely and improper lane changing are two specific behaviors that actually create slow downs. There are numerous models that simulate this.

I came here to point this out and love the way you stated it. Confusion, hesitation and unnecessary lane changes are what create traffic. There has never been a major highway development in history that didn’t cause at least some short term issues. We should give city planners a bit more credit than that