This summer, a Barnes Dance will go in at 14th and Irving Streets NW, right above the Metro station entrances. There's more than one way to set up an intersection like this, and the one DC chooses could have a big impact on bus traffic.
A Barnes Dance is an intersection where the traffic lights in all directions turn red at the same time so people can cross the street at any angle they want. The District Department of Transportation installed one at 7th and H Streets NW in Chinatown in 2016, and this past November Claire Jaffe and Nicole Cacozza reported that the agency was considering another at 14th and Irving.
There are different ways to do a Barnes Dance. How will this work?
The original Barnes Dance, named after Denver street commissioner Henry Barnes, is different from what DDOT has implemented at 7th and H St NW.
As originally conceived, the Barnes Dance does not allow pedestrians to cross in the usual phase, parallel to traffic that has the green. Instead, turning cars get precedence. Pedestrians are only supposed to cross during the all-clear phase.
At 7th and H, cars simply aren’t allowed to make any turns, and pedestrians can cross both during the all-clear phase and when they’re moving with traffic. That’s why DDOT calls the intersection an “enhanced” Barnes Dance.
We don’t yet know for sure which the one at 14th and Irving will be, though A report from the Washington Post’s Perry Stein makes it seem as though an original Barnes Dance is what's coming, and DDOT's website mentions that pedestrians won't be able "to cross the street while drivers turn left or right onto 14th Street".
Patrick Kennedy says that could be a problem for important bus routes:
[Allowing turns will] add to the already-considerable amount of time it takes for the H buses (and 50s, for that matter) to clear this intersection — at rush hours, especially, but really for much of the day. As it is, they get stuck in the right-hand lane of Irving behind vehicles making a turn onto southbound 14th…. There's really no good alternative to this line for crosstown commuters.
Barnes Dances are great, but they don’t work everywhere
Regardless of type, our contributors also had a number of ideas for other places to install Barnes Dances: Dan Reed suggested Ellsworth Drive and Fenton Street in Silver Spring, and Kristen Jeffers suggested 14th and U NW.
Tracey Johnstone said “M Street and Wisconsin Avenue DEFINITELY needs one,” but Stein’s specifically notes that DDOT officials determined the sidewalks there to be “too small to contain crowds that build while waiting for the traffic signal.”
Steven Yates said, “I'd prefer a Barnes Dance a block north at 14th, Park, and Kenyon. Right now it's an awkward arrangement of give streets that can be annoying to navigate.” Kristen Jeffers agreed, asking “could we just make that whole strip in front of DCUSA a Barnes? If I could just cross from Kenyon directly to entrance of the Target, that would save me several crossing cycles.”
But it turns out the complicated intersection of 14th and Park/Kenyon might not be the best idea. Multi-leg intersections don’t always make good for Barnes Dance locations. There are a lot of phases in the signal cycle, and so you might have to wait a very long time for the pedestrian crossing phase. Long waits tempt jaywalking, which defeats the purpose of the Barnes Dance.
The famous Barnes Dance outside Shibuya station in Tokyo isn’t really a multi-leg intersection; traffic only enters from four directions.
Matt Johnson gave an example of how one key assumption about how fast people walk determines a lot about how long traffic signal cycles take:
Under federal rules, a diagonal Barnes Dance has to be given a longer time than a perpendicular pedestrian crossing, because it covers a longer distance. This longer time means that adding a Barnes Dance makes the traffic signal cycle not just a little longer, but a lot longer -- for an intersection between two four-lane roads, it would add about 50% to the signal cycle length.
Under FHWA guidance, the pedestrian clearance interval is 3.5 feet per second. What that means is that if the crosswalk is across a street that is 48 feet wide (four 12' travel lanes), your [minimum] clearance interval [the time that “Don’t Walk” is flashing] is 14 seconds. Adding in seven seconds of walk, four seconds of yellow and two seconds of red, you get to 27 seconds for that phase of the signal. If the other street has the same dimensions, you can easily set up a 60 second cycle.
However, with a Barnes Dance, the cycle length changes, not only because you're adding in a third phase (N-S, E-W, all-ped), but also because the hypotenuse [diagonal crossing] is longer than either of the legs. For a 48 foot wide street, the clearance interval on each leg is 14 seconds, but the clearance interval for the Barnes Dance is 20 seconds. That's because the diagonal crossing is 68'.
In locations where the intersection is skewed, one of the diagonals can be significantly longer than the others, and that can make the Barnes Dance impossible.
At a complicated intersection like 14th/Park/Kenyon, pedestrians wouldn’t just have to wait for multiple streets to clear before the Barnes Dance cycle. Because complicated intersections are also wider, with even longer distances between the corners, adding a Barnes Dance to the cycle could substantially slow down everyone.
In fact, this is why Denver (which first popularized the Barnes Dance) officially had to end the dance. Matt added:
In downtown Denver, most intersections include an all-ped phase but it is not a Barnes Dance, because there are no pedestrian signals governing the diagonal crossing. But they used to. The difference is that FHWA changed the clearance interval calculation, and the additional signal time would have broken the signal cycle lengths. So, the all ped phase was kept, but only for crossing each leg. However, if you're able-bodied, you can easily make it across the intersection during the phase, and some people do. But it's not technically legal, because making it legal would require the diagonal ped signals.
Denver’s chief traffic engineer hinted as much at the time to the Wall Street Journal: pedestrians “will quickly figure out what they can get away with… if they hustle, they can probably make it.”
Correction: this post originally said it was unclear whether DDOT would be installing a traditional Barnes Dance or an "enhanced" one. DDOT's website makes it clear that it will be a traditional one.