The new Humpback Bridge project is starting its final phase. This is the bridge on the GW Parkway that carries the road (and the Mount Vernon Trail) over the Boundary Channel (which is that offshoot of the Potomac that hosts the Columbia Island Marina and is sort of a Virginia Tidal Basin). When completed (along with as-yet-incomplete trail improvements – more on that, below), this will offer two new access points to the 14th Street Bridge for Pikearea commuters – one via the footbridge onto Lady Bird Johnson Park via Columbia Marina to the northwest, and another to the southeast via Boundary Drive.
This is the southeast underpass to the left of the photo.
A few months ago I tried to check out the area on the Pentagon grounds where the SE underpass will spill out, but there were a lot of KEEP OUT signs so I chickened out. Arlnow suggests that the this underpass will, in effect, be useless for as long as two years.
The interchange from the 14th Street Bridge to the Mount Vernon Trail is in much, much better shape now as the project winds down.