Synesthesia Vision integration with Recife's Public Transport
Aida A. Ferreira, Gilmar Brito, Lydia Nascimento da Silva, João Victor Mouzinho, Ryan Morais, Jonathan Romualdo Pereira · 2019 · Proceedings of the 16th International Web for All Conference (W4A) · doi:10.1145/3315002.3332446
Summary
This demonstration paper presents Synesthesia Vision, a two-component assistive technology system for blind people in Recife, Brazil, and its integration with the metropolitan public transport monitoring system. The system consists of sensory glasses (3D-printed frames containing an Arduino microcontroller, ultrasonic sensors, a Bluetooth module, and physical buttons) and a companion smartphone application built with the Ionic hybrid framework. The sensory glasses detect obstacles in the user's path via ultrasonic sensors and communicate distance measurements to the smartphone, which converts them into spatialized 3D audio — allowing users to perceive the location and distance of obstacles through headphones. The smartphone application also provides contextual environmental information: weather forecasting (via GPS location and the Open Weather web service, requested by a blind user who needed to know whether to bring a guide dog), ambient brightness detection (using a sensor on the glasses to determine if lights are on or off), and — the paper's main contribution — real-time bus schedule and arrival information. The public transport integration connects to web services provided by the Greater Recife Consortium, which monitors approximately 2,500 buses (including the BRT fleet) through the SIMOP system with onboard satellite tracking. The application identifies the user's GPS location, finds the nearest bus stop within a configurable radius (default 350 meters), and lists available bus lines, schedules, and predicted arrival times. Key features are accessible via physical buttons on the glasses — allowing one-click access to weather or bus information even when the phone is locked.
Key findings
Volunteer testing produced promising results, with participants reporting that the system gave them greater security to walk independently and go alone to bus stops. The integration addresses a specific accessibility gap in Recife where bus routes, lines, and schedules are communicated only through visual signage — making public transportation effectively inaccessible for independent use by blind people. The system is designed as a low-cost solution using consumer hardware (Arduino, standard smartphone) and is freely available on the Google Play Store. The mobile app works independently of the sensory glasses, meaning users can access the bus schedule features without purchasing the glasses hardware. The participatory design aspect is noteworthy: the weather forecasting feature was specifically requested by a blind user who needed it for guide dog decisions, demonstrating that user involvement in design yields features that developers might not anticipate. The choice of hybrid app development (Ionic/Cordova using HTML, CSS, JavaScript) enabled cross-platform deployment while leveraging the accessibility ecosystems built into mobile operating systems.
Relevance
This work demonstrates how integrating assistive technology with smart city infrastructure can significantly expand independence for blind people in everyday activities. Public transportation is a critical point of exclusion: when bus information is only available visually, blind people must either depend on others for help or avoid public transit entirely. The Synesthesia Vision system addresses this by combining obstacle avoidance (for safely walking to the bus stop) with real-time transit information (for knowing which bus to take). For accessibility practitioners working in smart city contexts, this paper illustrates that accessible transit information requires more than accessible websites or apps — it requires integration with real-time vehicle tracking systems and location-aware delivery that anticipates the user's context. The project also shows how IoT concepts can benefit accessibility: by connecting wearable sensors, smartphone capabilities, and web services, the system creates an ambient awareness layer that partially compensates for the absence of visual information. The developing-nation context (Brazil) is significant, as public transit is often the only affordable transportation option, making its accessibility directly tied to employment, education, and social participation.
Tags: visual impairment · blindness · public transportation · smart city · obstacle detection · spatial audio · 3D audio · Internet of Things · wearable technology · navigation and wayfinding · Brazil · developing nations