Fifteen minutes of half-time churn. Wet, loud and busy, and everyone is trying to get somewhere.
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.
A concourse only exists in bursts. For fifteen minutes at half time a stadium empties tens of thousands of people into a ring of corridors, at around 1.9 people per square metre, with alcohol being served throughout.
On paper the conditions are good: 85 dB gives a 1.6 metre speech range, wide enough for a group, and the drinking rate is comparable to a nightclub. What kills it is that 55 percent of the crowd is in transit and attention sits at 0.40 — there is a bar to reach, a toilet queue to join, and a whistle coming.
The result is the lowest encounter rate of any drinking venue here at 8.15 per person per hour. A concourse is a nightclub with a deadline, and the deadline wins.
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.
Every gathering below is modelled as this kind of room. Attendance figures are published numbers for the period stated.
Around 1.9 people per square metre — Fruin grade E — for roughly fifteen minutes, which is why concourse width is a major factor in stadium safety design.
More than half the crowd is in transit with a fixed deadline. In this model that cuts the encounter rate roughly in half compared with a venue at similar density and drinking rate.
90,000, making it the largest stadium in the United Kingdom and the second largest in Europe.
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.
