The preferred concept for the Mt. Vernon Trail to Long Bridge Drive connection

Arlington County is planning a rebuild of the Boundary Channel Drive, Interstate 395 and Long Bridge Drive interchange, which is located just east of the Pentagon. This rebuild will include shared use paths along both sides of Boundary Channel Drive with connections to the Mount Vernon Trail, via the stub "Pentagon Lagoon Trail" built in 2011 as part of the Humpback Bridge project, and to Long Bridge Drive and Long Bridge Park. 

In June of 2015, they held a public information meeting and released three design concepts and since then the project has been

]working through a Federal Highway Administration/Virginia Department of Transportation technical analysis known as an Interchange Modification Report (IMR). This report will include a technical model to test a number of design concepts for the interchange and ultimately lead to a preferred alternative for this important transportation gateway to Arlington County.

It's not clear how soon the IMR will be completed, but it does appear that their is now a preferred design as recently reported to the County Board.

 

East of I-395, the preferred concept uses Concept 1 and west of it it uses Concept 2 except on the far west end. On the west end, the preferred design has no trail on the south side of Boundary Channel (west of the Pentagon Access Road) and on the north side, the trail stops a few feet shorter - at the driveway along the Pentagon Lagoon.

The path will have a design speed limit of 18mph.  

Design of the fully funded Boundary Channel Drive Interchange project is expected to begin in 2017, with construction forecast to start in 2020.

Comments

[darren]

Disappointing. Many people at the community meeting emphasized the importance of minimizing conflicts between trail users and highway access ramps, and this recommended design doesn't do that.

[kathy]

Frankly the existing design is far better than this. Hit head against wall.

[washcycle]

I don't know Kathy, the existing design doesn't connect to the MVT. This design is much better than what is there now IMO, it just may not be ideal.

[DaveS]

We currently have MVT -> LBJ Grove (after and under humpback) -> Boundary Channel Bridge -> Boundary Channel Drive -> Long Bridge Drive. It's somewhat indirect but very low conflict.

Or we have MVT -> (turn before and under humpback) -> dirt path -> Boundary Channel Drive -> Long Bridge Drive. That's more direct, but requires using the ramp for crossing NB traffic at Boundary Channel Drive.

The preferred concept gives us a trail where the dirt path is and keeps us off Boundary Channel Drive, but it also requires trail users to cross both on and off ramps for 395.

At a roundabout.

Drivers headed to or from 395 will have to track motor vehicle traffic in the roundabout and look for people on the trail. Trail users won't be able to judge if traffic is continuing around the roundabout or using an exit. Drivers may see trail users paused on the refuge islands and presume any users on the main trail are also stopped - and the refuge islands seem too small for more than a couple of people. (Will this add a bunch of the trail stop signs and "dismount to cross" points that we detest everywhere else?)

And that's just looking at the leftmost exchange. The rightmost one has the same problems, and it repeats some of them for a slip lane from Boundary Channel Drive to Long Bridge Drive (and 395), then asks trail users to cross it.

For road-confident cyclists, the merge from the dirt path to Boundary Channel Drive to turn right on Long Bridge Drive becomes a turn off the trail, two roundabouts, and contention with traffic headed for 395.

I agree, this is not ideal. I'm not sure it's actually better, and in some ways it sure looks worse than the no-build no-trail option - but it'll be smoother and faster for the drivers that trail users will be dealing with.

[washcycle]

OK, well the first option doesn't go away, this only changes the 2nd option.

And really, the 2nd option doesn't either. Only the dirt trail part, which I see as an improvement. The new option doesn't keep us off Boundary Drive, it gives us the option to stay off of it. But, you can bike right to that exact same spot as now and do the exact same thing. Except now you have a crosswalk and an island. So, for that you come out ahead too.

But - you will also be able to stay on the trail. This does come at the cost of having to make some at-grade crossings, so some may prefer it and others may not. But, I don't see how having more options - even bad ones - is a loss.