The cellular view of a street crossing
Denser than any dancefloor, and almost nothing forms — because nobody stops.
The conditions of this room
Four numbers decide what a crowd does: how tightly it is packed, how loud it is, how fast alcohol arrives, and how much attention is available for the people beside you. Everything below is either a published figure or derived from one.
What those conditions do to people
This is the control case for everything else on this site. A scramble crossing reaches about 3.5 people per square metre — denser than a packed club — and it is quiet, so speech carries nearly 2.8 metres. On the two variables that a nightclub optimises for, the crossing wins outright. It should be the most social place in the world.
It produces 0.2 encounters per person per hour, against a nightclub's 17.6. Over four hours, 1,200 people leave nine lasting ties between them, and the largest connected group in the entire crowd is seven people.
The difference is a single variable: attention. Everyone here has somewhere to be and roughly forty-five seconds to get there. In the model that appears as a transit factor of 0.01 — a person crossing with purpose is a hundredth as available to a stranger as a person standing still. Bodies being close is not the same as people being present, and the crossing is the proof.
What the model produces
Measured output from a standard run: 1,200 people, 4 hours of venue time, fixed seed, no parameter overrides. Every room on this site is run under identical conditions, so these figures are a like-for-like comparison rather than a set of individually flattering runs.
The crowd is a simulation and is presented as one. What is not invented are its constants: walking speed against density, the proxemic zones, the collapse of speech range with noise, the Widmark blood-alcohol curve and the conversational group limit all come from published work, cited above and listed in full in the engine.
Real places like this
Every gathering below is modelled as this kind of room. Attendance figures are published numbers for the period stated.
Questions
How many people cross Shibuya at once?
Up to about 3,000 people per light change, with roughly 2.5 million crossings a day, making it the busiest pedestrian crossing in the world.
Why do people not talk to strangers in public?
Not because of density or noise. In this model the decisive variable is attention: someone moving through a space with a destination is roughly one hundred times less available to a stranger than someone standing still, which is why a quiet, extremely dense crossing produces almost no contact.
Is a crossing more crowded than a nightclub?
Yes. A scramble crossing peaks around 3.5 people per square metre against a dancefloor's 2.0 — both Fruin grade F and E respectively. Forward movement is near-impossible above 5.4 p/m².
How this is modelled
Each person is one cell with a position, a body mass, a Widmark distribution ratio, an openness trait and a reserve of energy. They walk at the speed the local density allows, drink at the rate the room serves, and when two of them stay within speech range long enough, a bond forms. Most bonds are nothing.
What separates an encounter that creates something from one that does not is whether it bridges two groups that were not previously connected. A tie inside an existing group mostly restates what that group already knows; a tie across a gap carries information neither side had. That distinction is Granovetter's, and it is the mechanic the whole model turns on.
One parameter has no citation and should be read as an assumption: attention, the share of a person available to whoever is beside them rather than to a stage, a road or a rite. It is the variable that separates a street crossing from a dancefloor at similar density, and it is the one this model asserts rather than borrows.