Wiki · Arcology history · Mathematics · Crowd flow
Wiki Arcology history · Mathematics · Crowd flow
When a packed corridor stops being a crowd and starts being a fluid — Earth pedestrian science, plus a classroom sketch.
Earth pedestrian science, framed for 2490 readers. The widget is educational. It is not Concordia egress control and not a campaign document.
Engineers do not use one crowd model. They pick a resolution. A whole sector emptying at once is a density-and-velocity field. A single doorway is a set of bodies with elbows. A family that will not split is an agent with a rule. 2490 scholarship can file all four without pretending Concordia’s halls were certified by a named solver.
When the question is “can this district empty,” modelers often treat the crowd as a fluid. The Navier–Stokes equations — the same family used for water in a pipe or air over a wing — reappear with density standing in for pressure and walking speed for velocity. A bottleneck compresses the flow. If someone falls at the front, a shock can travel backward. That is why stadium and pilgrimage research spends so much time on geometry: the crush is a physical wave, not only a mood.
Dirk Helbing’s Social Force Model (1995) treats each pedestrian as a particle under Newton’s second law, with “forces” that are mostly psychology: a desire toward a goal, a wish to avoid walls, a wish to keep personal space. As density rises, those repulsions pack the particles and slow the stream. A published and counterintuitive result: a pillar in front of an exit can speed an evacuation by breaking the pressure arch that forms when a crowd aims at a single gap.
The classroom sketch on this cluster uses a toy version of that idea — desire plus repulsion plus an optional pillar. It is not calibrated to a code, and it is not a Concordia drill.
Cellular automata chop the floor into cells (often about 40 cm on a side, one standing person). Each tick, an occupant may step into a neighboring empty cell according to simple probabilities. The method is cheap enough to run on a large plan. It reproduces lane formation and zippering at crossings without giving anyone a biography. It is a planning screen, not a person.
Agent-based models give each dot a profile: slower walkers, groups that refuse to split, a few who panic. Unpredictable pile-ups can emerge from those rules. Architects then test cues — lighting, signage, extra doors — against the mess. The computation is heavy. The ethics are heavier if someone treats the output as a decision about whom to save. Public pages do not go there.
Try density and the pillar. Watch whether the door clears or clogs. Then read it as Helbing-flavored pedagogy, not as a map of the Laser District.
Educational sketch · Social Force Model (Helbing, 1995) · not a Concordia egress tool
Dots are particles with a desired velocity toward the door, plus repulsion from walls, neighbors, and an optional pillar. Raising density or removing the pillar often builds a pressure arch at the gap — a published result in pedestrian dynamics, not a recipe for Concordia bulkheads. Prefer reduced motion? The sketch stays paused until you press Play.
0 still in the room · 0 through the door
Same widget, with the other sketches, on Tools.
No bulkhead timing. No oxygen shutoff. No reconstruction of named Concordia events. Game systems stay a HUD page. If you want the civic timeline, use History.
Parent: Mathematics. Control: Control. Packing and graphs: Space-packing.