Richard Allen
The stretch on the beltway between 95 and north of Tysons is the worst. There can be snail pace traffic in that section anytime of the day or night.

There is an alternate route that is to the west of the beltway. You get off of I-95 at Dale City and head towards Manassas. This route will eventually take you up 15 to Fredrick MD.

Check Yahoo Maps - directions and look at the alternate routes.