The built environment must be universally accessible to help create inclusive, equitable, and sustainable cities so that persons with disabilities, older adults, and those with mobility impairments can fully participate. Even with existing standards and universal design principles aimed at removing barriers, empirical research indicates that implementation gaps persist across diverse urban settings. This paper provides a systematic review of 30 peer-reviewed empirical studies published between 2007 and 2026. By using universal accessibility audits, systematic checklists that are consistent with national and international guidelines, field observations, user interviews, participatory assessments, and spatial analysis methods, the studies in this paper analyzed public buildings, walking paths, transport, and parks, and other urban areas in places across Asia, Europe, North America, and others. Results indicate that compliance is consistently low to medium, with universal accessibility scores often ranging from 14% to 45% in shopping malls, old buildings, sidewalks, and open spaces. The prevailing physical barriers include poor ramps, uneven or blocked routes, a lack of curb cuts, insufficient signage, and discontinuous pedestrian networks. Systemic factors such as lack of awareness among professionals, variability in regulatory application, financial constraints, policy-practice linkages, and the disposition to reduce universal accessibility to a retrofit instead of a design factor are underlying factors. The review concludes that effective improvements require active, combined efforts: integrating universal design as a key part of early planning; strengthening enforcement and observation; enhancing stakeholder training and education; prioritizing participative user-centered approaches; and utilizing standardized yet flexible measurement tools and data-based analyses. Addressing these gaps is essential to promote social equity, community inclusion, and sustainable urban development.

universal design, built environment, universal accessibility, urban planning, compliance audit, implementation barriers