Preventive Inclusive Design for Invisible Disabilities in Urban Planning: A Study on Color Blindness and the Reproduction of Disability

Subject Areas : urbanism

Faezeh Sanjabie ¹ , Atefeh Dehghan Tooranposhti ² , Seyed Majid Naderi ³

1 - Department of Art and Architecture, WT.C., Islamic Azad University, Tehran, Iran.
2 - Department of Art and Architecture, WT.C., Islamic Azad University, Tehran, Iran.
3 - Department of Art and Architecture, WT.C., Islamic Azad University, Tehran, Iran.

Received: 2025-08-03 Accepted : 2025-09-21 Published : 2025-09-23

Keywords: Inclusive design, Color blindness, Invisible disability, Spatial justice, Non-disclosive design,

Abstract :

This article explores how “invisible disabilities” are reproduced through urban design, focusing on color vision deficiency (CVD, or color blindness) as a prevalent yet often overlooked case. Although not outwardly apparent, CVD restricts wayfinding, risk perception, and social participation in everyday urban life. To address these systemic constraints, the paper advances the concept of preventive inclusive design: embedding accessibility and perceptual diversity from the earliest planning stages so barriers are avoided rather than retrofitted. Methodologically, the research combines conceptual–critical analysis with spatial semiotics, interrogating how meaning is encoded in urban sign systems and how those codes are differently legible across perceptual spectra. Color-perception simulations—modeling deuteranopia, protanopia, and tritanopia—are applied to metro networks, station concourses, squares, and other public settings to stress-test legibility under conditions such as crowding, low light, and time pressure. Comparative cases from Tehran and London demonstrate how reliance on color alone becomes an exclusionary convention. Findings show that dependence on color produces “silent exclusion”: users with CVD experience increased cognitive load, route errors, slower decisions, and avoidant behavior, particularly in emergencies or complex interchanges. By contrast, layered and multisensory systems—clear text labels, pictograms, numbering schemes, patterned backgrounds, luminance contrast, tactile indicators, and selective auditory prompts—reduce misinterpretation without generating clutter. Inclusion, therefore, is less about adding more color than diversifying information channels and ensuring redundancy across them. Framed through perceptual justice, the study extends theories of spatial justice by recognizing that equitable access depends not only on infrastructure but also on perceptual legibility and sensory inclusivity. Urban design, as a semiotic system, distributes resources and interpretive opportunities, shaping who can participate fully and who is tacitly excluded. On this basis, the article proposes “design without disclosure” as a guiding principle: environments should enable participation without requiring individuals to self-identify, request exemptions, or carry proof of impairment. This reframes disability from
an individual deficit to a sociotechnical outcome of design decisions, professional conventions, and institutional standards.
The paper contributes three advances. First, it reframes CVD as a systemic design issue aligned with the social model of disability, showing how nonvisible differences are marginalized by color-dominant conventions. Second, it introduces a semiotic audit for planners and designers that integrates simulation stress tests with redundancy and contrast checklists, enabling early detection of failure points in concepts and specifications. Third, it outlines a policy toolkit linking building codes, transport guidelines, procurement, and maintenance regimes to enforce multisensory signage as standard practice rather than exception. Practically and ethically, preventive inclusive design lowers retrofit costs, mitigates risks, widens usability, and affirms dignity by avoiding stigmatizing, ad-hoc measures. While demonstrations focus on transit and public spaces, the framework generalizes to campuses, hospitals, parks, and event venues where wayfinding and risk communication are critical. The article closes with actionable recommendations: parallel coding for color-dependent messages, minimum luminance-contrast thresholds, consistent iconography, tactile and auditory reinforcements at key points, and routine simulation reviews at each design stage. Together, these measures operationalize “design without disclosure” as a pathway toward perceptual justice in inclusive urbanism and provide a foundation for equitable policy-making

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