No blocking of cars, but the traffic hasn't been bad the last two years. That's the beauty of the early start time, despite the fact that I am not a morning person. And the shorter route is mostly low-traffic or wide shoulder roads. Dunno about the section that branches off for the longer route, though.

I usually average 12-15mph so it'll take me 4-5 hours, depending on breaks, photo ops, and such.