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Yale campus intersections

2020-03-21 20:32 GMT

You know those all-way walk sign intersections at Yale? The ones where, in between cars moving, people can walk diagonally from one corner from the intersection to the opposite corner. Apparently they are also called pedestrian scramble or Barnes Dance intersections. The Wikipedia page even says that Henry Barnes advocated for them because his daughter had a hard time walking to school (though Wikipedia’s source for this does not say this).

They are the best.

They’re great for pedestrians and cyclists, and bad for cars (I strongly dislike cars, but that’s for a different post). In almost all respects, I’m really happy with them. But there’s one thing that I keep thinking of every few weeks.

Yale map section

I present this screenshot I took of Yale’s online map to help explain my issue. I’ve marked what I’m pretty sure are the six most-walked Barnes Dance intersections by undergraduates at Yale.

  1. Elm & York (in front of Patagonia)
  2. Elm & College (Battell)
  3. Grove & College/Prospect (Woolsey, SSS)
  4. Canal/Trumbull & Prospect (Grove Street Cemetary, Franklin)
  5. Sachem & Prospect (Watson)
  6. Grove & Church/Whitney (Willoughby's, Bruegger's)

Living in Morse, I cross (1) pretty often. After a few crossings you figure out when the all-walk light turns on. For (1), it happens right after the light for cars heading roughly East on Elm Street, heading from Whalley and Broadway towards the New Haven Green. Importantly, there is no all-walk light after the green light for cars on York Street–only after green for Elm Street. Fine.

Without loss of generality, let’s say that this all-walk lighting scheme has the Barnes Dance efficient property, or the BDE property for short. Formally, if lights repeat in the order of:

  1. Green for the roughly North-South street
  2. Green for the roughly East-West street
  3. Walk for all pedestrians

Then this street has BDE.
(Note that the street has the Barnes Dance efficiency property, rather than is Barnes Dance efficient. Saying that a street is BDE might philosophically commit me to positions I’m not comfortable with.)

As I claimed earlier, intersection (1) has BDE. What about intersection (2)? It too has BDE. The all-way sign shines after Elm again. Same with intersection (3). In front of SSS might be Yale’s most famous Barnes Dance intersection, and most people have figured out to just start walking after the cars on Grove go.

We arrive at intersection (4). Criminally, it does not have BDE. I have witnessed with my own eyes countless times that the all-walk sign lights up after the green light for Prospect, not Canal/Trumbull.

You know what gets me? Intersections (5) and (6) also have BDE! What is wrong with the light at Canal/Trumbull & Prospect? Is a little consistency too much to ask? I really need people to check me on this to make sure I’m not going crazy.

Yale, like all of us, is imperfect.


A brief note on activating the all-walk sign. If no one presses the walk button, it gets skipped. So that means if you’re the first person at the intersection, it’s your job to press the button. I’ve put my trust in too many strangers who have arrived at an intersection before me and failed me.