Dimensions of Compact Urban Form and Carbon Emissions from Transport in Indian Cities

As cities strive to reduce carbon emissions, the way they are physically structured plays an important role in shaping travel patterns and energy use. Compact urban form is preferred as a strategy for sustainable urbanisation worldwide. However, compactness of an urban area is multidimensional, and the role of each dimension in shaping carbon emissions from transport remains insufficiently understood in the Indian context. This study addresses that gap by examining five dimensions of urban form—density, shape, contiguity, spatial concentration, and fragmentation—for 27 Indian cities. Each dimension is examined in relation to carbon emissions using three complementary methods, namely quadratic regression, generalised additive model, and segmented regression. Results show that shape is the strongest and most robust linear predictor, with irregular urban forms linked to higher emissions. Density shows a negative relationship, suggesting lower emissions at higher densities. Fragmentation shows a non-linear pattern, with a threshold at 0.785 (95% bootstrap confidence interval: 0.594–0.829). After correction for multiple comparisons, this pattern is considered as suggestive rather than confirmed. Contiguity and spatial concentration display no consistent effects. These findings indicate that strategies focused on reducing shape irregularity along with densification may offer effective pathways for emission reduction from transport in Indian cities.