Are we measuring what matters? A multilayered framework evaluating active mobility infrastructure through PLOS, BLOS and 15 minute city principles

Active mobility is increasingly recognised as the cornerstone of sustainable urban development. Providing suitable infrastructure for walking and cycling is essential for promoting active transport and achieving its associated environmental and health benefits. However, systematically evaluating the suitability of active mobility infrastructure remains a methodological challenge. This paper presents a multilayered conceptual framework designed to assist policymakers, practitioners, and researchers in assessing active mobility infrastructure by integrating Pedestrian and Bicycle Level of Service models with the principles of the 15 min city. The hierarchical framework organises six broad constructs, such as Facilities, Geometric Design, Built and Natural Environment, Amenities, Proximity and Accessibility, and Flow and Traffic Characteristics, under which 138 unique indicators are classified. A systematic review of 78 studies using the PRISMA protocol guided the development of this structure, revealing both commonly cited and underutilised indicators critical for infrastructure evaluation. The three-layered framework illustrates how pedestrian and cyclist experiences are shaped by the interplay between physical infrastructure, its surrounding environment, and functional performance. It enhances conceptual clarity, reduces redundancy and ambiguities caused by overlapping terminologies, and supports evaluation at both micro and macro scales. It introduces the "Golden Nuggets", i.e., the essential indicators for evaluating non-motorised infrastructure and highlights underused but important metrics. The framework also recommends scaling segment-based assessments to route- and network-based levels, advancing current PLOS and BLOS models. Future research should focus on empirical validation across spatial scales and the development of indicator weighting schemes to enhance the framework’s application as a practical, scalable, and transferable evaluation tool.