Loudoun County is very annoying in terms of transportation. Why? Just look at a map. Loudoun County Pkwy has so many unconnected segments! Creighton Rd doesn't go anywhere!

The problem you describe is an artifact of the odd system Virginia as a whole uses to fund transportation and other civic improvements. It is called the "proffer" system and it means that the improvements are directly tied to the schedule of the development on the land, not to the county plans for roads, etc. A developer promises or "proffers" the roadwork (or whatever) return for a rezoning. But they only fix the road directly in front of their land, not all the road. The rest of the road has to wait for more development. Or, the money isn't turned over for the improvement until a certain amount of development is built, or a certain amount is sold. That's why one corner of an intersection that needs an overpass may get built up but the overpass has to wait until all four corners are built up. Or you get the stop and start completion of a parkway.

The result is that the improvements ALWAYS lag behind.

Hope that helps.