MABLESim: A Simulation Framework for Studying Accessibility Challenges for People with Disabilities within Indoor Environments
Francisco Javier Rafful Garfias, Vinod Namboodiri · 2024 · Proceedings of the 21st International Web for All Conference (W4A) · doi:10.1145/3677846.3677852
Summary
This paper introduces MABLESim (Mapping for Accessible BuiLt Environments Simulator), a Unity-based simulation framework designed to study how people with disabilities navigate indoor spaces. The authors address a fundamental research gap: while physical accessibility barriers in buildings are well documented, studying them systematically is difficult because collecting real-world mobility data from people with disabilities navigating unfamiliar indoor environments is logistically challenging and ethically complex. MABLESim transforms 2D architectural floor plans into 3D digital models where simulated individuals with different disability profiles can navigate between source and destination points. The framework models two critical parameters that shape navigation outcomes: mobility speed (calibrated from real-world observations of blind users, wheelchair users, and walkers) and wayfinding decision success rate (WDSR), which captures how likely a person is to choose the correct path at branching points. WDSR accounts for differences in how well individuals can perceive and interpret wayfinding signage — for instance, blind users who cannot see signs have a much lower WDSR than sighted wheelchair users. The simulation treats navigation as a series of decisions at branching points, with wrong turns incurring backtracking penalties that vary by disability group. The authors demonstrate the framework using two real university buildings: Wallace Hall (compact, simple layout) and the Health Sciences and Technology building (large, complex layout), simulating 30 source-destination pairs for four population groups across each building.
Key findings
The simulation results confirmed and quantified several expected patterns while revealing important nuances. Blind individuals needed roughly four times as long as non-disabled individuals to navigate the larger, more complex HST building, compared to about three times as long in the smaller Wallace Hall — demonstrating that building complexity disproportionately impacts people with disabilities. Navigation efficiency (ratio of shortest route distance to actual navigation time) dropped by 50% or more when moving from the simpler to the more complex building, with the sharpest declines for blind users. Motorized wheelchair users were actually slower than non-motorized wheelchair users or walkers, reflecting programmed speed limits on motorized devices and observed cautious behavior in crowded or complex environments. Varying the WDSR parameter showed that improved wayfinding signage (higher C_k values) substantially reduced navigation time and increased efficiency, with the benefits being most pronounced in the larger, more complex building. This suggests that investing in better wayfinding signage and technology yields the greatest returns in complex indoor environments where people with disabilities face the steepest challenges.
Relevance
MABLESim offers a practical tool for architects, facility managers, and urban planners to evaluate indoor accessibility before committing to physical modifications. By simulating how different disability groups experience a building, designers can identify problem areas — such as overly complex branching corridors with inadequate signage — and test interventions virtually. The framework highlights that legal compliance alone does not ensure usability: a route may technically be accessible yet be fifty times longer than the stairway alternative. For accessibility practitioners, the key takeaway is that building complexity and wayfinding signage quality are critical yet often overlooked factors that dramatically affect real-world navigation for people with disabilities. The framework is currently limited by its use of average mobility speeds per group and simplified backtracking assumptions, and it does not yet capture the full range of physical and psychosocial factors in real navigation. However, it provides a scalable starting point for evidence-based accessibility assessments that could complement traditional audits and user testing.
Tags: indoor navigation · wayfinding · simulation · mobility impairments · visual impairments · built environment · wheelchair users · physical accessibility
Standards referenced: Americans with Disabilities Act · WCAG 2.1