# Co-location Epidemic Tracking on London Public Transports Using Low Power Mobile Magnetometer

## TL;DR

This paper proposes a novel method to track co-location of individuals on London public transports using smartphone magnetometers, enabling epidemic monitoring without additional sensors.

## Contribution

It introduces a new approach leveraging geomagnetic field sensors on smartphones to detect co-location in transit environments, validated over extensive real-world travel data.

## Key findings

- Effective co-location detection over 150 km of travel
- Applicable across trains, tubes, and buses in London
- Potential for epidemic spread monitoring

## Abstract

The public transports provide an ideal means to enable contagious diseases transmission. This paper introduces a novel idea to detect co-location of people in such environment using just the ubiquitous geomagnetic field sensor on the smart phone. Essentially, given that all passengers must share the same journey between at least two consecutive stations, we have a long window to match the user trajectory. Our idea was assessed over a painstakingly survey of over 150 kilometres of travelling distance, covering different parts of London, using the overground trains, the underground tubes and the buses.