> They're low density even if you account for increased travel radius due to cars. What does it mean, exactly? How do you "account" for the increased travel r

> They're low density even if you account for increased travel radius due to cars. What does it mean, exactly? How do you "account" for the increased travel radius? Do you divide by the distance or by the distance squared? Are you sure that in both cases the density is low? It does not seem so, to me.