I was driving a normal speed and following traffic in front of me at a safe stopping distance. I hear honking and this vehicle is within feet of my bumper trying to get me to go faster. They then speed around me on the right and force their way in front of me causing me to have to break hard not to hit them. Seconds later they are tailgating the next person in front of them and then do the same thing to them. It seemed very likely that they could cause an accident. I was going above the speed limit already to keep up with traffic so they had to have been going at least 20 over to get around me as quickly as they did.