Those 4 houses close to the wall were probably given the option of being bought out. Some people decide they want to stay. Future buyers know what they will be facing.
Good luck to those who want to sell the homes. If they're even lucky enough to sell, they'd be loosing a lot of money. Their home values must have plummeted. I couldn't think of a person who would want to purchase a property at that location.
Unless they bought their home several decades ago, chances are it was already inexpensive for Springfield due to the traffic noise at that location. The area from the Beltway to the Springfield interchange has been a loud area for quite some time. They may even think it's better than before.
It seems surprising where people are willing to buy or build a home, all kinds of noisy places.
This was a quiet residential area, and this home was built within a year of this segment of I-476 being built near Villanova, I lived near there then and saw it all. http://tinyurl.com/yybp5wsb
It still appears that specific example could still be a quiet area. That home you mention is buffered from the freeway by trees and a soundwall. Somebody on that property may not even recognize the soundwall because it's covered by the trees. Could be a nice property nonetheless. I-476 is also sunken, with County Line Rd bridging over the interstate.
Here's a more recent example of a similar situation with
I-73 in Greensboro, NC. This segment of interstate was built in 2008, and required taking a path through this neighborhood. The highway is raised over the residential street, but an 70 - 80 foot buffer between the property closest to the highway, and the highway itself was provided. Some decorative planting and garden design, along with some trees were planted in these buffers, giving it some aesthetics. Soundwalls were also provided on the freeway and on the overpass. Somebody on I-73 wouldn't even know they're going over a residential street.
A good design concept IMHO when having to push a highway through a residential area, but also upkeep the area at the same time. A buffer is probably the most important thing. If those people wanted to stay though, then that's beyond VDOT, and it was nice of them to not evict them at that point either way.