Pedestrian Flow Analysis

Measuring pedestrian flow means observing real movement — counting people across a screenline, tracking them on video, or sensing them with infrared or Wi-Fi — to obtain volumes, densities and speeds. Modelling means simulating movement from rules, either microscopically (agent-based or social-force models that move each walker) or via the aggregate fundamental diagram. In practice the two are coupled: measurements calibrate and validate the models, and the models then predict situations that have not yet been observed, such as a redesigned station or an evacuation.

It is the empirical relationship between pedestrian flow, density and speed on a walkway. As density rises from empty toward jammed, walking speed declines, so flow (the product of density and speed) first increases to a maximum — the walkway's capacity — and then falls as movement becomes congested. Fitting this curve to local counts gives the capacity and level-of-service thresholds used to size footpaths, stairs and platforms.

Each pedestrian is treated as a particle accelerated by a few simple forces: a driving force pulling them toward their destination at a preferred speed, and repulsive forces pushing them away from other people and from walls and obstacles. No global rule tells the crowd to form lanes or queue at a door, yet when many such agents are integrated forward in time these patterns emerge spontaneously — which is why the model reproduces lane formation, exit clogging and stop-and-go waves seen in real crowds.