The older adolescents are, the less frequent they use their bike for transport. However, cycling is good for health and for the environment and climate. Cycling safety is an important factor determining adolescents’ choice for a specific cycling route. With this research, cycling safety along adolescents’ routes between their home and school will be analysed, both at macro- and at micro-scale. In a first phase, cycling routes of adolescents will be analysed using data mining methods. Several potentially important environmental factors (e.g. the presence of cycle lanes, land use, street type) along their routes will be taken into account. This PhD research will evaluate which of those factors determine adolescents’ route choice. In a second phase, the collected cycling data will be used to detect dangerous intersections in the neighbourhood of schools. Video-cameras will be hung at those intersections to record interactions between the different road users. Dangerous and safe manoeuvres will be investigated. From these outcomes, several limitations of such intersections will be determined. The results from both phases can reveal important points of interest for the environment along adolescents’ cycling routes, and for specific intersections. This information is important for local authorities that want to improve cycling safety.