DOI RECORD
Built Environment and Travel Carbon Emissions: Consistency and Contextual Limits
Abstract
Associations between the built environment and travel carbon emissions remain difficult to generalize due to heterogeneity in indicators, outcomes, spatial scales, and methods. Using synthesis of effect directions, we integrated 1,290 association records from 115 empirical studies into 457 study–indicator assessments. Proximity to urban centers exhibited the most consistent low-carbon association (k = 32; net direction score [NDS] = -0.688). Land-use mix also showed predominantly negative associations, although their directions varied across definitions, scales, and urban contexts. Associations differed substantially across direct emissions, travel activity, and mode choice, indicating that greater use of low-carbon modes does not necessarily correspond to shorter travel distances or lower emissions. Nonlinear patterns and heterogeneous turning points further highlighted contextual dependence. These findings distinguish relatively consistent from context-dependent associations and underscore the importance of assessing behavioral and emission outcomes separately.