By monitoring mobile phones searching for Wi-Fi signals, DTU students are testing a tracking system with the capacity to show how many people are present, how they move, and where they go.
How long is the queue for food? Do we need to make more food, or is there already too much? Where are the festival-goers heading, and might this give rise to safety issues? These are questions the DTU students will be looking to answer with the so-called ‘TrackSafe’ system.
“We’ve set up eight sensors in the Food Court, where there are all kinds of food stalls and a single stall selling beer,” relates Peter Juhl Savnik, who is studying electrical engineering at DTU.
The idea is eventually to help the stalls optimize staffing and prepare exactly the right amount of food required so as to limit food waste. However, a system such as TrackSafe can also be used to improve safety by highlighting situations where there are too many people gathered together in too small an area.
“For example, we noted that more than 7,500 people streamed past our sensors in just ten minutes when the gates to the festival area were opened on Wednesday,” says Peter Juhl Savnik.
Large-scale test
The project is part of a major DTU project that involves installing sensors in the lamp posts on DTU Lyngby Campus. The intention behind testing the set-up at Roskilde Festival is to help develop the system and provide new knowledge.
"Throughout the day, the longest queue consistently formed at the beer stall, but then suddenly at 1 a.m. the food stalls were most popular."
Peter Juhl Savnik.
“It’s a large-scale test that should help us find out more about the opportunities presented by the system,” continues Peter Juhl Savnik.
“For instance, we need to modify the algorithms because as things stand we are receiving far too much information, which slows the system down. The server has received more than 4.7 million data points over the course of a single day, and this volume of data makes huge demands on the relatively small server we’re using here.”
After just one day, the system has unveiled some interesting observations about the Food Court customers. The concentration of festival-goers can be displayed on what is known as a ‘heat map’, which turns red when there are a great many people in one place.
“Throughout the day, the longest queue consistently formed at the beer stall, but then suddenly at 1 a.m. the food stalls were most popular,” explains Peter Juhl Savnik. “This is something the people running the stalls should take into account.”
To help the people running the Food Court outlets optimize conditions at the various stalls, they receive a daily report about customer behaviour from TrackSafe.
Complies with the Personal Data Act
The eight sensors in the Food Court contain a tiny Raspberry Pi computer and a Wi-Fi module. The sensors track mobile phones that are automatically searching for a Wi-Fi connection—even when the phone is in standby mode.
So registration requires no direct action on the part of the phone owners. A newly developed algorithm that anonymizes the users ensures that the system complies with European data protection legislation.