Driving when you're tried is dangerous when you're driving a golf cart or a bicycle. It can be downright deadly if you're driving an 80,000-pound semitruck.
You've seen the aftermath of a semi accident. The semi was barely damaged, but the car it hit was a mangled wreck. You know that drivers in other cars are in a lot of danger if they're involved in one of these crashes.
Trucks have slower speed limits than passengers cars on some roads in New York. This is done to keep people safe. With their massive size, it's harder for trucks to turn, stop or avoid accidents, so they're told to slow down to reduce the number of crashes.