Autonomous Navigation through the City for the Blind
Jaime Sánchez, Natalia de la Torre · 2010 · Proceedings of the 12th International ACM SIGACCESS Conference on Computers and Accessibility (ASSETS 2010) · doi:10.1145/1878803.1878838
Summary
This paper presents a study on the use of an audio-based GPS navigation application designed to help blind people navigate independently through urban environments. The software, developed for PocketPC devices with Bluetooth GPS receivers, uses a clock metaphor to communicate directions — treating 12 o'clock as directly ahead and other hours as relative directions, which proved more intuitive for blind users than cardinal compass points or left/right instructions. The system has a minimal three-button interface: one to select a destination from a spoken list, one to request current distance and direction information, and one to change the starting point. All output is delivered through text-to-speech via the Acapela TTS engine. The study was conducted in Santiago, Chile over seven months with seven participants aged 15-55 who were legally blind, recruited from the Helen Keller School for the Blind, the Blind Corporation, and the National Union of Blind People in Chile. Participants first completed preparatory cognitive tasks — learning the clock direction technique using a physical model clock with tactile PVC markers, estimating distances in steps, and familiarising themselves with the device — before navigating eight real routes through the city ranging from 544 to 1,506 metres, passing through culturally significant locations such as metro stations, museums, and parks.
Key findings
All participants were able to reach every assigned destination using the audio-based GPS software, achieving a group mean performance score of 11 out of 17 points across routes. Route 1 (the shortest at 544m) had the best performance (mean 12.71), while Route 6 (the longest and most complex at 1,506m) had the lowest (mean 9.14), though ANOVA showed differences between routes were not statistically significant. The Route Evaluation Guide showed all users improved their navigation and reached destinations autonomously without needing prior knowledge of the environment or dependence on other people. Self-evaluation surveys revealed participants gained confidence over time — initial routes showed higher degrees of hesitation, but with practice these problems were overcome. The clock technique was particularly effective for communicating turns and direction changes. Participants who habitually navigated only with companions were able to navigate independently. However, the software did not provide information about street crossings, obstacles, or the physical environment — users had to rely on their existing orientation and mobility skills and environmental awareness for safety. The study also noted that commercial GPS maps often lack sufficient detail for pedestrian navigation, particularly regarding sidewalk-level routing.
Relevance
This study demonstrates that relatively simple audio-based GPS technology can meaningfully expand the independent mobility of blind people in urban settings, even without sophisticated obstacle detection or detailed pedestrian mapping. The clock metaphor for communicating directions is an elegant design solution that leverages a universally understood spatial reference — practitioners designing navigation aids should consider this approach over cardinal directions or abstract turn instructions. The research also highlights important limitations that remain relevant today: GPS accuracy at the pedestrian scale (standing on a sidewalk vs. in the street), the lack of obstacle and crossing information, and the gap between vehicle-oriented digital maps and pedestrian needs. For accessibility professionals, the study underscores that navigation technology for blind people must be paired with orientation and mobility training, not treated as a replacement for it.
Tags: blind navigation · GPS · orientation and mobility · mobile technology · assistive technology · audio navigation · urban accessibility · text-to-speech