I am looking into these two houses, both are back to Kirby road. If the windows are open, you can clearly hear the car passing by,not sure if there are buses.
This one locates at entrance of the sub:
http://www.redfin.com/VA/Falls-Church/6666-Avignon-Blvd-22043/home/9477799, sold in 2006 as 1.25m, and today asking for the same.
Another one locates inside of the sub, but also back to Kirby:
http://www.redfin.com/VA/Falls-Church/6686-Avignon-Blvd-22043/home/9477889.
Would you be bothered by noise? They both sit there for some time, longer than their neighbour houses. If you buy it, would be concerned for future selling in difficulty?