Road Talk: a Roadside Location-Dependent Audio Message System for Car Drivers

We present the Road Talk application which is a mobile message system for car drivers. It is designed to allow messaging while driving, for instance, sending notes to surrounding drivers to tell them about hazards. The user annotates the road with audio recordings, typically voice memos. This annotation is location-based, which means that messages are automatically coupled to the location where the audio was recorded. When another driver coincides with this location the audio file is automatically played. In the background, messages are also shared with fellow car drivers. This distribution draws on wireless mobile ad hoc networking (MANET) and the physical movement of vehicles. We designed messages to spread ‘epidemically’, since MANETs between vehicles are often disconnected. Messages hop from one car to the other when there is coverage and then passively travel some physical distance. Then they hop again when coverage reappears. The design of Road Talk is motivated and informed by a statistical analysis of commercially available systems for distributing warnings of speed trap events. These events occur where police monitors conformance to speed limits and although our intention is not to improve these services the analysis gave insights in, for example, temporal and spatial occurrences of roadside location-dependent messages.