Originally Posted by
Rampo
I don't know the actual cost but the
VRE is probably cheaper than Amtrak although timing is very important. You can take the VRE to L'Enfant Plaza, then catch the 5A bus to IAD from there. Again, not the most direct or convenient way of doing it.
What time of day do you need to get there? VRE is a good option, but doesn't run on weekends or holidays and predominantly runs in the direction of rush hour (looks like there are two northbound trains in the afternoon/evening).
Amtrak will be somewhat better in terms of frequency for off peak times, but still, it's not like there is hourly service from Quantico or anything--it's far enough south to be mostly off the DC public transportation grid.