I hear you sister.. When our child was in elementary school, I was very active in the PTA and the drop off pick up was always a huge pain. We had some VERY close calls. There were also some deaths in the little towns around us at the time.one parent ran over her own child and another town a woman backed over a child.. . that really made us vigilant.
No matter how many times, we would send out notes, emails and warnings, parents just did not think it applied to their "Situation"..Everyone has an excuse.. Finally one year we actually trained the kids in class as to the proper way for the parents to drop off and pick up. It was pretty funny to hear the parents complain that their children refused to step between running cars and yell at their parents to "keep on driving!" Hee, hee,,
The other thing is we had a really funny dad put on a referee shirt with a yellow flag. and a whistle. He would motion using football gestures to let people know if they screwed up..
The final thing we did was document repeat offenders and ask them to help us come up with solutions. ie We put their butts out there to watch morning drop off and pick up, up close and personal. We sent the requests through their children saying, "could you make sure your mom sees that we really need her help with this project! " The kids were so excited they of course got the parents out there..
We also had sandwich boards made that were easy to read that reiterated "No cutting," "No passing", "Keep moving".. Our daughter has not been there in over 10 years and I notice they still use them.