Locating people in tunnels using Wi-Fi technology

The aim of the project is to investigate the possibility of using people's mobile phones to locate people in a tunnel environment using the mobile phone's Wi-Fi connection. In total, 39 different trials were carried out under different conditions in a road tunnel in Stockholm, Sweden. In the trials, the Wi-Fi-based predicted location has been compared with the actual location of the recruited 16 participants in the tunnel. The conditions include the number of people in a group, the number of available access points in the tunnel, whether the mobile phone has an active or passive connection, whether a person is moving or standing still and whether the mobile phone is held in the hand or is stored in the person's pocket. The results indicate that the mean value for the distance between actual and predicted locations is in the order of 20 m or less, which is higher than reported in other studies. Despite this, there is a good potential to locate individuals in a tunnel emergency as the distance between emergency exits is often much longer than the uncertainties in the predicted locations of people. Improving the location algorithms will possibly reduce the uncertainty of the predicted location.