Does non-conforming urban development mean the failure of zoning? A framework for conformance-based evaluation

Abstract

The conformance approach is frequently used to evaluate the effectiveness of spatial plans in containing urban sprawl. However, non-conformances are widely considered inevitable. Prior conformance-based evaluations fail to answer the essential question of whether plans influence non-conforming situations. To address this gap, we built a framework for conformance measurement to reveal how plans affect non-conforming urban development. The multi-indicator framework includes quantitative indicators, the spatial distribution relationship between new non-conforming urban land and zoning maps, and the location and original land use of new non-conforming urban land. When applied to a case study, this framework reveals that most new non-conforming urban land was adjacent to conforming urban land and located in zones without strict restrictions on urban development. Moreover, the type of land use that the zoning map aimed to conserve was rarely converted, suggesting attempts by decision-makers to control the severity of conflicts between non-conforming development and the zoning map. A logistic regression also evidences the significant influence of zoning on non-conforming urban development. These findings, in turn, verify the operability and theoretical value of the proposed framework.