Larger cities use less built material per resident, NYU study finds

Larger cities generally contain less built material per resident than smaller ones, according to new research by NYU scholars that examines how urban form affects the physical resources needed to house and connect people.

Published October 26 in Nature Cities, the study by Kangning Huang and Mingzhen Lu maps the mass of buildings and transport infrastructure across 3,588 cities. It combines satellite observations with information about the materials used in construction.

Across the cities studied, a doubling of population was associated with about 87% more built mass, rather than twice as much. Within equal-area neighborhoods, the corresponding increase was about 68%. These are comparisons across places, not measurements showing that a particular city’s infrastructure investment has failed to keep pace with its growth.

Sharing structures changes material demand

NYU’s announcement describes how denser development lets more people share foundations, roofs, structural cores, roads and other infrastructure. The researchers connect these efficiencies to urban planning choices, including rules that constrain density.

For planners and engineers, the findings suggest that material requirements should be evaluated alongside urban form. A projection that simply multiplies today’s material use per person by a larger future population may miss the effects of shared structures and networks. That is a planning implication, not a prescribed spending reduction.

The study also has boundaries. Built mass is not a measure of service quality, maintenance condition or spare capacity. The authors note that underground pipes, cables and other elements that remote sensing cannot capture remain outside the inventory. Water, power and transport systems still require their own demand and performance assessments.

The work provides a framework for considering resource efficiency as cities develop. It does not establish a universal density target or show that every growing city already has adequate infrastructure.