City Population, Street Traffic, and Daily Passage
Population and traffic figures are not interchangeable. Each dataset answers a different factual question, and the halachic view determines which question matters.
Resident population
A census counts people whose primary residence lies inside a defined area. It is useful for the size of a city or neighborhood but does not directly count daily users of a particular street.
Commuters, visitors, shoppers, students, and people passing between boroughs may use the public network without living inside the proposed eruv. A neighborhood population can therefore understate the public served by its roads.
Traffic and passage
Vehicle counts record vehicles, not people. Pedestrian counters cover the location and hours in which they operate. Transit entries count boardings, and road capacity describes possible movement rather than actual passage.
These figures should not be added as though they measured one identical population. Each can illuminate the city, but the method must match the halachic definition being applied.
Daily, regular, and citywide use
Some formulations focus on daily passage; others examine the population served by the city streets more broadly. The chosen period affects whether occasional visitors, rush-hour concentration, and repeated trips by the same person are counted.
A sound calculation states the period and geographic area before presenting the result.
The halachic premise comes first
The responsible Rav first decides which view of shishim ribo governs the eruv. Only then can census, transportation, and mapping data answer the right factual question.
A precise number cannot repair an undefined premise. The strength of the conclusion depends on the halachic rule and the evidence being about the same thing.