I see the reference further up the thread showing that the CTB is apparently ready to "study" the idea again, but I'd still say not to expect it any time soon and not to expect it to be an easy project by any means. That is a very tight location.
It'll be interesting to see how the planned extension of Frontier Drive affects traffic flow in that area. I don't know when construction is scheduled to begin. It will involve reconstructing the interchange between Frontier Drive and the Parkway and changing the traffic flow around the Metro stop. Part of the reason for the project is the new (yet-to-open, insofar as I know) TSA headquarters southwest of that interchange. Since that matter is interchange-related, it fits in this thread. You can find diagrams of what's planned here: http://www.virginiadot.org/projects/resources/NorthernVirginia/Frontier_Drive_Extension_Displays.pdf I like the idea of eliminating the "weave area" on the westbound Parkway where traffic using the loop ramp to leave the Metro currently comes to a stop sign and then has to cross over traffic heading for the exit ramp to Frontier Drive. The speed limit on the Parkway is 50, but it's not unusual to see 70+, so getting rid of the stop sign will be a safety improvement in multiple ways. I do wonder how well that roundabout is going to work. There's a lot of very bad driving on the roads around that parking garage, including people regularly driving the wrong way on the one-way access road in order to take a shortcut to a garage entry, so I have to wonder how many people will yield properly and such at the roundabout.
IMO now that VA-286 (Fairfax County Parkway, formerly 7100) is complete across Fort Belvoir North Area (including the interchange at Barta Road) between
Fullerton Road and the
TOTSO interchange (for VA-286) at Rolling Road and VA-289 (Franconia-Springfield Parkway, formerly 7900), the connection between I-95 and VA-286 north of the TOTSO is not perfect, but much improved, I think the pressure may be off for completing a (
very expensive) interchange for all movements at I-95 and VA-289.
If I was deciding (and I am not), I would much rather see some of the at-grade signalized intersections on VA-286 converted to grade-separated interchanges.
Some of my candidates (south to north, not in order of merit):
Terminal Road (hundreds of petroleum tank truck trips are observed every day of the week);
Loisdale Drive (too close to I-95);
Reservation Drive (lot of pedestrians cross VA-286 here to get to the park areas on the west side);
Lee Chapel Road (busy intersection);
Old Keene Mill Road (many injury crashes and fatal crashes);
Burke Lake Road (also a busy intersection);
Burke Centre Parkway (busy intersection);
Popes Head Road (busy intersection);
Franklin Farm Road (lots of pedestrian traffic here);
West Ox Road (busy intersection);
Sunrise Valley Road; VA-267 (Dulles Toll Road) and Sunset Hills Road (all of this should be blown-up and rebuilt to eliminate the signals at Sunrise Valley and at VA-267; that the interchange at 267 was built as a rural-style diamond baffles me)