TL;DR for operators An event operator deciding whether to narrow an entrance, separate opposing flows, or redirect pedestrians needs to know whether congestion will actually ease—or simply move upstream or into another corridor. PedNStream1 provides a fast way to compare such interventions by representing pedestrians as aggregate flows moving through connected corridors rather than simulating every person individually. ...
A city drainage engineer rarely gets to choose between perfect data and bad data. The real choice is more annoying: a few sensors in the right places, a few sensors in the wrong places, or a procurement request large enough to frighten everyone in finance. Urban flood monitoring has always had this observability problem. Storm sewers are spatial systems. Water does not politely report its location from one convenient manhole. It moves through a network of subcatchments, conduits, junctions, slopes, storage, bottlenecks, and hydraulic thresholds. Full visibility would mean dense instrumentation across the network. That is expensive to install, maintain, power, calibrate, secure, and occasionally rescue from the weather doing exactly what it was installed to measure. ...