We collect the sensor data and location information after you first click start logging button on the main screen. After you start logging, the app will run in the background and collect your location information and sensor data. It is worth noting that you can stop logging in anytime when you click stop. We require this information to perform our research study. Also, we only use phone serial numbers to distinguish different users and this won’t be associated with your identity. The location information and sensor data will be sampled at a high frequency from the device. Our app will only upload your compressed and encrypted data to our AWS server and delete the collected data file immediately after uploading. Once we receive the information, we keep it on our servers, and we don’t share it with any third-party entity. GPSLogger_FHWA never engages in any communication with any external entities and doesn’t leak any type of information. This app is based on another app "GPS Logger for Android" by Mendhak -- a lightweight, battery-efficient GPS Logger.