Really, it's not bad at all on the roads on that route I posted. The worst part is on River Road right at the beginning, but even then there's not much traffic. And if you stay way to the right, car drivers don't seem to get too irritated. You WILL get your hill work in!

Maybe I'm more willing to tolerate traffic since I commute into DC on a busy, narrow street every day, but it seems like trail riding to me.