Estimating local daytime population density from census and payroll data

Geoff Boeing

doi:10.1080/21681376.2018.1455535

Abstract

ABSTRACTDaytime population density reflects where people commute and spend their waking hours. It carries significant weight as urban planners and engineers site transportation infrastructure and utilities, plan for disaster recovery, and assess urban vitality. Various methods with various drawbacks exist to estimate daytime population density across a metropolitan area, such as using census data, travel diaries, GPS traces, or publicly available payroll data. This study estimates the San Francisco Bay Area's tract-level daytime population density from US Census and LEHD LODES data. Estimated daytime densities are substantially more concentrated than corresponding night-time population densities, reflecting regional land use patterns. We conclude with a discussion of biases, limitations, and implications of this methodology.

Highlights

Where Pt is the tract’s population; It is its inbound commuters; Ot is its outbound commuters; and At is its land area
The densest tract – comprising the central Financial District and Union Square neighbourhoods – contains over 127,000 persons/km2 during the day, when its population swells by a factor of 40
Region-wide, the tract daytime population’s Gini coefficient is 70% higher than that of night-time population (0.36 versus 0.21), suggesting that people concentrate into fewer tracts during the day but disperse more evenly among all tracts when they return home at night

Summary

Introduction

We merge4 these data with the Bay Area tract-level population and calculate daytime population density D for each tract t as: Dt It − At where Pt is the tract’s population; It is its inbound commuters; Ot is its outbound commuters; and At is its land area (km2). The median daytime population density across all Bay Area tracts is 2097 persons/km2, but the distribution has an extreme right tail: the standard deviation, s, of Figure 1’s highest quantile (15,330) far exceeds the average s across its other quantiles (249).

Results

Conclusion