Originally Posted by
redtop43
A lot depends on time of day. From DCA to IAD the normal route is the GW parkway north to I-66, then to the Dulles access road.
I-66 is HOV only from 4:30 to 6:30 (maybe it's 4:00) - totally HOV, not just HOV lane. Because of the Dulles access road, they can't ticket until you get past the turnoff, meaning that people start to get on around 6:20. So if you hit I-66 before 6:15 you're in the clear; by 6:30 it's a parking lot all the way to the Dulles cutoff. The Dulles access road however will be smooth sailing. It can only be used by vehicles going to IAD (there are no exits until the airport).
I'm writing this at 6:40PM on a weekday and Google Maps shows that DCA to IAD is 29 miles and 33 minutes,
Your info is outdated. I-66 is now HOV two with mandatory transponder from 3:00 to 7:00 pm. If you aren't HOV two with a transponder, you can use I-66 but at a significant toll.