QueueTrak: Automated line length detection using a wireless sensor network

We describe QueueTrak, an automated wireless sensor system designed to detect and report the length of lines in retail environments. QueueTrak has two components. First, it uses a series of custom active infrared sensors to detect the length of a line in a store or restaurant. Second, a web interface publishes the data, at the discretion of the shopkeeper, for use by customers, city planners, and other shopkeepers. We empirically evaluate the system design and find that it can accurately estimate line length despite noise caused by variations in natural sunlight or moving people and furniture in the store.