As Automated Vehicles (AVs) will be deployed in mixed traffic, they need to interact safely and efficiently with other traffic participants. The EU H2020 project interACT works towards the safe integration of AVs into mixed traffic environments. Across three European countries (Germany, Greece, & the UK), data was collected on how human traffic participants interact in real traffic conditions currently. This data was used by the interACT project team to develop, implement and evaluate novel external Human-Machine Interface (eHMI) and internal HMI (iHMI) elements to enable AVs to communicate both with surrounding road users and on-board users.