Without a doubt, OTR truckers. Most major accidents are caused or contributed by them. Look at the latest Indiana incident. Six lengths for every 10mph would have prevented this. If they would follow the knowledge of most drivers, no more than one truck would ever be involved in an accident. I would like to see semi's limited on the road from 9pm to 6am. It would make the roads safer for all of us. I really hate truck drivers in bad weather.