The overburdening of city transport systems is becoming an increasing challenge. But before cities can take concrete action, they need to gather precise traffic data. This is often very time consuming and expensive. A study by the Fraunhofer Institute for Industrial Engineering IAO in cooperation with Telefónica NEXT and the data analysis specialist Teralytics found that mobile network data can make a positive contribution to transport planning. To clarify, analyses were carried out for the city of Stuttgart with the help of anonymised and aggregated mobile network data, which provide detailed insights into the actual travel behaviour of Stuttgart residents. This gives an idea of the data’s potential.