Better off This Way!: Ubiquitous Accessibility Digital Maps via Smartphone-based Crowdsourcing

Accessibility maps are key to support individuals with disabilities to actively participate in the society. The Americans with Disabilities Act (ADA) defines minimum requirements for roads and other public accommodation spaces to be accessible. Yet, it is sufficient to have one accessible route in a place, and available digital-maps lack accessibility information to help finding that accessible route. In this paper, we present the AccessMap system to automatically extend road-maps with accessibility semantics. It enables indoor and outdoor spaces to he automatically marked as visually-impaired and/or wheel-chaired accessible/inaccessible. AccessMap passively crowdsources measurements from sensors available in the users' smartphones to detect accessibility semantics. It employs a probabilistic framework to build and update the map with the semantics. Evaluation of AccessMap in different countries shows that it can passively detect a widerange of accessibility semantics with high precision and recall (on average around 89.8% and 863% respectively). Furthermore, its probabilistic crowdsourcing framework increases the generated map's average precision and recall to 98.7% and 99% with as few as seven encounters per semantic.