Non-linear associations between zonal built environment attributes and transit commuting mode choice accounting for spatial heterogeneity

Understanding how built environment attributes are associated with transit commuting mode choice is essential for planners to promoting transit through land use and transportation policies. Scholars usually assume that their relationships follow a (generalized) linear pattern and are homogeneous over space. These assumptions may lead to inconsistent estimates. This study develops a semi-parametric multilevel mixed logit model to identify non-linear and spatially heterogeneous relationships between built environment attributes and transit commuting in Nanjing, China. The results show that built environment variables in residential areas have saliently non-linear associations with transit commuting, and the associations vary across traffic analysis zones. Densification facilitates transit use but it has a diminishing return. A medium level of mixed-use is conducive to transit commuting. Transit supply has to exceed a certain threshold to be effective. These findings offer nuanced guidance for transit-oriented neighborhood planning.