Traffic is a numbers game. I've often observed that in free flowing traffic where I live (a tiny city with only about 700k people in the entire metro) that if you take two cars that are a safe following distance apart there will be 5 cars in between. If we put in 6 times as many lanes (already a 3-4 lane freeway each way, so we are talk 20 lanes for my tiny city!) traffic wouldn't go any faster, but they would space out to most maintaining a safe following distance. (if you put in 7 times as many lanes they would get farther apart yet, but still not go faster)