The impact of urban form on physical change: A quantitative and diachronic analysis of urban form evolution in Midtown Manhattan

The importance of urban form as a key factor affecting future development and transformation patterns is well-recognised in urban morphology. However, despite the need for a diachronic approach to rigorously understand the form-change relationship, studies utilising longitudinal datasets remain scarce, and only a small fraction employs quantitative methodologies and morphometric approaches. This paper aims to quantitatively examine how the character of urban form elements and their spatial arrangements influence patterns of physical change, and to assess the performance of geometric and configurational urban form measures of plots, buildings, and streets in explaining physical change patterns over time. We hypothesise that configurational measures, being more sensitive to the relations between urban form elements, can better explain physical changes compared to conventional geometric measures predominantly adopted thus far. To test this hypothesis, we present a diachronic and quantitative methodology to measure urban form conditions and the patterns of physical change in Midtown Manhattan through four time frames (1890, 1920, 1956, and 2021), using a longitudinal geospatial database generated from historical cartographic resources and recent digital datasets. The association between urban form and physical change is demonstrated through statistical analysis. The findings prove that while the prevailing hypotheses emphasising the effect of geometric measures, such as size and shape, are often off the mark, configurational and access-based measures of plots and streets can accurately describe the dynamic relationships between form and change. The character of urban form patterns and structures measured by configurational variables is more reliable than the individual and geometric quality of urban form elements in explaining the dynamics of physical change and persistence. Our empirical findings add to the rapidly expanding fields of urban morphometrics and provide data-informed insights to improve the resilience and adaptive capacity of urban spaces.