You are right when you say traffic safety messages best hit home when you show the aftermath of careless driving.

I do p.r. work for The National Road Safety Foundation, which for years has been producing and distributing free films and classroom teaching materials to educate and change behavior among young people regarding drinking & driving, speeding and aggressive driving and, most recently, drowsy driving.

Check out their website and you’ll see how they show the impact of bad driving behavior on the victims and their friends and families. Go to http://www.nationalroadsafety.org

these ad campaigns may be enough to shake people

I have had some similar PSA ideas
but I am not a film maker