A typo-morphological approach to frontage zones’ potential for urban green infrastructure

Street networks are central to strategies aimed at extending urban green infrastructure (UGI) as they represent a multifunctional network that spans entire urban areas. However, competition of uses in these zones is intense; therefore, adjacent surfaces between the property line and the facade should also be considered for streetscape greening. The potential of frontage zones, also known as front gardens or yards, has been little explored in research and requires enhanced methods to assess their capacity to extend the UGI. This study refines a GIS method to identify frontage zones, their morphological characteristics, and vegetation cover. Subsequently, an exploratory data analysis provides insights into the relationship between morphological and vegetation characteristics. Lastly, a hierarchical clustering approach helps define types of frontage zones and highlights those which hold particular value for the integration of UGI. The study encompasses frontage zones across the entire municipal area of Munich, Germany, thereby including a variety of urban structure types. The results categorise six frontage types with varying morphological and vegetation cover characteristics. They indicate that frontage depth is the most influential variable for vegetation coverage, and that frontage types are distributed across multiple urban structure types. These findings underscore the untapped potential of the various frontage types in increasing vegetation cover in streetscapes and advocate for their strategic inclusion in UGI planning strategies.