My directions to NRAO-ER from Washington:
Its a 2 hours drive from Dulles, provided you aren't trying to travel during rush hour. From the airport, take the first "real" exit on the right for 28S (I think it says to Leesburg, and probably also says to 66W on it) [NOTE: the very first exit is for airport parking; the exit for 28S is immediately after that]. You'll stay on 28S for ~10miles, to 66W. Stay on 66W for about 12mil to 29S at exit 51 (Gainsville) [note: If you are coming from DC rather than Dulles, there is an earlier exit for 29, but you don't want that]. Take 29S for about 90 min straight into Charlottesville.
You should recognize when you are near CV as you pass about a million shopping centers. You pass one with a McDs, Burger King, Bed-n-bath, Harris Teeter, and Taco Bell all on the right, then you start seeing university housing. Rt29 is now called "Emmett Street". At the 2nd light there will be a motel (Cavallier Inn) on your right, Exxon gas station on your left. You'll want to turn right here. This street is called Ivy Road on the right, and University Avenue to the left. After turning right (onto Ivy Rd), go to the next light (just past a Hardies on your right; Banks on both corners). This is Alderman Road. Turn Left. Go to the next light (past a church, plant services on right). This is McCormick Road. UVa Astronomy is directly on your right. Take a right onto McCormick. At the stop sign, bear right (dorms on your left, Slaughter recreation center in front of you). NRAO is the next complex on your right. I am in room 312. 804-296-0227