Global Study Reveals Asymmetric Cause and Effect Relationship Between Urban Development Patterns and Road Traffic Congestion

ETH Zurich researchers find that urban form and land use are the primary causes of traffic congestion, offering new predictive tools for sustainable city planning.

By: AXL Media

Published: Apr 30, 2026, 5:42 AM EDT

Source: Information for this report was sourced from EurekAlert!

Decoding the Complex Symbiosis of Cities and Mobility

The relationship between urban expansion and transport infrastructure is often viewed as a circular dilemma where new housing demands better roads, and improved roads invite further development. However, a new study led by ETH Zurich and the University of Wisconsin provides a deeper understanding of this mutual dependency by establishing specific cause and effect relationships. Published in Nature Communications, the research argues that sustainable urban design requires a fundamental grasp of how mobility and city structures interact. According to lead author Yatao Zhang, the mounting pressure on modern transport systems makes it crucial to move beyond simple road expansion to address the root causes of congestion.

A Comparative Analysis of Thirty Global Metropolitan Centers

To investigate these dynamics, the research team analyzed a diverse group of 30 major cities, including Zurich, Los Angeles, and Singapore. The scientists utilized high resolution traffic data from Here Technologies, which tracks congestion levels globally at five minute intervals. For instance, in Los Angeles alone, the study incorporated data from over 18,000 individual road sections. This congestion information was correlated with various urban characteristics, such as road network architecture and the geometric shape of green spaces and residential districts. By integrating this with functional data on housing, shopping, and education from Open Street Map, the researchers created a comprehensive profile of how each city operates.

Moving Beyond Infrastructure to Functional Urban Form

While the expansion of road networks remains a significant factor in traffic volume, the study highlights that the spatial arrangement and function of buildings are equally decisive. The research team developed an innovative method to describe how these urban features influence traffic over time. The findings suggest that sprawling cities naturally generate higher traffic volumes, whereas mixed use developments that combine living and working spaces tend to reduce commuting distances and overall congestion. As Zhang puts it, traffic is a byproduct of human activity rather than a simple consequence of road existence. This shift in perspective places the emphasis on how land is utilized rather than just how many lanes are paved.