Accessible Indoor Navigation
Kyle Montague · 2010 · Proceedings of the 12th International ACM SIGACCESS Conference on Computers and Accessibility (ASSETS 2010) · doi:10.1145/1878803.1878884
Summary
This doctoral consortium paper presents early-stage research on designing an accessible indoor navigation application for disabled users. Montague identifies a key gap: while outdoor navigation benefits from GPS, indoor wayfinding remains a significant challenge because GPS is unreliable inside buildings and existing Indoor Positioning Systems (IPS) are complex and expensive. The research focuses on hospitals as a primary use case — large, multi-floor buildings with numerous entrances, stairwells, elevators, and inconsistent signage that pose particular difficulties for people with disabilities. The project aims to create a mobile application that provides personalized navigation instructions tailored to individual accessibility needs. For example, a wheelchair user would be routed via elevators and ramps rather than stairs, while a blind user would receive audio instructions instead of text. The paper reports on two studies: an initial study examining how people naturally give wayfinding instructions, and an interaction study evaluating a working prototype. The instruction study with 4 male and 3 female participants at the Queen Mother Building revealed a consistent structure in navigation instructions: Action (what to do), Context (direction), and Reference (landmarks), delivered as preparation, decision, or confirmation statements.
Key findings
The prototype was built as a mobile web application using JSP, with a SOAP client for iPhone access, incorporating a user model that tracks interactions and adapts the interface accordingly. A simplest-path algorithm based on Dijkstra's shortest path was implemented, with distance weighting modified to account for junction complexity and user preferences — for instance, wheelchair users receive higher cost weightings for stairs, making elevator routes preferred. An interaction study with 4 elderly users (ages 60-86) using iPod Touch devices showed the tool was generally easy to use, but revealed a critical limitation: the prototype could not establish the user's location within the building without external positioning technology. One participant walked past a door and received instructions relative to a position they had already passed, highlighting how indoor positioning failures cause instruction errors. The user model successfully adapted instruction format (text vs. audio) based on user behavior, such as automatically providing audio transcriptions when a user repeatedly pressed the audio button.
Relevance
This research addresses a practical accessibility gap that persists today: indoor navigation remains far more difficult than outdoor navigation for people with disabilities. The personalized routing approach — adapting paths based on mobility needs and adapting instruction format based on user preferences — represents an important design principle for accessible navigation tools. The Action-Context-Reference instruction structure discovered in the initial study provides a useful framework for anyone designing wayfinding instructions. While the technology has advanced significantly since 2010 (with Bluetooth beacons, Wi-Fi fingerprinting, and Apple's Indoor Maps), the core design challenges identified here remain relevant: the need for adaptive user models, personalized routing that considers accessibility requirements, and the critical importance of accurate indoor positioning for instruction reliability.
Tags: indoor navigation · wayfinding · adaptive interface · mobile accessibility · assistive technology · user-centered design