North Capitol Street Cloverleaf Feasibility Study

Last year DDOT did a study on North Capitol Street and how to make it less of the commuter highway it is now and more of grand avenue

The corridor of North Capitol Street under study has less to do with the formal streets and grand avenues associated with Pierre L’Enfant’s 18th century plan for the District of Columbia than mid-20th century engineering for maximal traffic flow. By ignoring its role in the city’s fabric, North Capitol Street serves one type of traffic only, auto, rather than addressing the equally important pedestrian, bicycle and transit needs that are so ably handled by the many fine examples of multi-use streets found in the District.

The report has been completed, and it has some good proposals within.

North Capitol is a major north-south route in the District and a bicycle unfriendly road where speeds regularly exceed the 45 mph speed limit. I biked it once. Only once. As it's the only route through the Old Soldier's Home site, it's inaccessibility makes for a major barrier for those traveling N-S. Irving Street was also part of the study and it too is an uninviting place for cyclists. The study has designs on changing that.

Improvements to the study area should enhance the existing networks and provide more transportation options by filling these identified gaps. For example: connecting sidewalks, allowing for dedicated bike lanes, creating a hiker/biker trail along North Capitol Street.

The study recommends three solutions for the three sections of North Capitol. For the north section - from Irving to Hawaii Ave - it recommends an "Urban Parkway." For the section south of Irving it recommends an "Urban Boulevard." And it recommends replacing DC's only cloverleaf, the intersection of Irving and North Capitol with an "Urban Center".

The Parkway would attempt to be similar to Rock Creek and as such would include a hiker-biker trail along the west side, separated from the road by a planting zone and low stone wall. It would also involve more trees, bioswales, etc...

The Boulevard section would have no bike facilities, but it does aim to make the street better for cyclists. It doesn't really say how though.

The Center has three possible configurations.

The first replaces the cloverleaf with a complex intersection that has Irving passing over North Capitol, the second carries North Capitol over Irving on a giant octagonal deck with the road down the middle, and the third carries North Capitol over Irving on a smaller traffic oval.  The third is probably best for cyclists as the oval's curves should slow traffic some. It also happens to be the best economically ($51M to build, with $188M benefit).

In addition the study suggests a bike lane on a road-dieted Irving Street.

Picture via DDOT

Comments

[Mark]

Dare I say that stretch of Irving is the most over-built road in DC? DDOT could instantly improve that road for cyclists by turning the storm drains and installing a few speed cameras. It's good to hear changes are being considered.

[a]

"DC's only cloverleaf"

SE/SW freeway
Suitland parkway
whitehurst
16th street
the entrance to 66
anacostia freeway
south capitol
maine avenue

all have clover leaf interchanges.

not that they all shouldn't die a horrible death, but more than one exists.

[washcycle]

I meant the only full (four leaf) cloverleaf

SE/SW freeway - nope.
Suitland parkway - 3 leaf
whitehurst - nope.
16th street - nope.
the entrance to 66 - nope.
anacostia freeway - 3 leaf and 2 leaf
south capitol - nope.
maine avenue - nope.

[a]

i'm probably just being anal and nitpicky and stretching the idea of cloverleaf. but its interesting.

SE/SW freeway - nope.
-@ barney circle

whitehurst - nope.
-@ k and 27th and rock creek.

16th street - nope.
-at military

the entrance to 66 - nope.
-just southeast of the kennedy center

anacostia freeway - 3 leaf and 2 leaf
-and another three leaf @ penn se.

maine avenue - nope.
-@14th.

[washcycle]

I think a cloverleaf, when viewed from above has teardrop shaped loops where drivers go 270 deg around to go a different direction.

"A cloverleaf interchange is a two-level interchange in which left turns (in countries that drive on the right) are handled by loop roads (U.S.: ramps, UK: slip roads). To go left (in right-hand traffic), vehicles first pass either over or under the other road, then turn right onto a one-way three-fourths loop ramp (270°) and merge onto the intersecting road."

The places you've noted are interchanges, but not cloverleafs.

[Froggie]

Froggie's Roadgeeking 101...;o)

By definition, a cloverleaf has loop ramps and regular ramps in all four quadrants. Or 8 ramps total. Thus...North Capitol at Irving is the only one in the District.

If an interchange has loop ramps, but not meeting the above criteria, most state DOTs consider it a partial-cloverleaf, or par-clo. The Anacostia Fwy interchanges at Malcolm X/Bolling, Suitland, and Pennsylvania qualify as such, as well as Military Rd at 16th St NW.

The I-66, Whitehurst, and Barney Circle ramps are, by definition, not loop ramps (curved yes, but not loop), so they don't qualify.

14th at Maine is a special case. Yes there's a loop ramp there, so technically it's a par-clo. But there's effectively only 3 ramps there to begin with so it's a very partial interchange.