Presentation for the IxD18 - Interaction Lyon Conference. Touch screens in fast moving vehicles: providing a great user experience. Spring 2016, Digipolis Antwerpen designed a new connected police vehicle for the Antwerp police force. Test vans contained dedicated touchscreens that allowed users to access FOCUS: a digital platform that supports field officers on the job. Passengers could use this interface while the van was headed towards an incident. This specific context confronted us, the FOCUS UX designers, with very specific design challenges. Which environmental aspects influence the usability of a touchscreen in a police van? How do you optimize the physical installation of the screen? What are the optimal font and tap target sizes? During this talk, we will tell about our approach to define design guidelines for this specific context. We’ll discuss the contextual problems, our assumptions, the research plan and test setup. We’ll give a closer look at the user test execution and will end by sharing our findings and guidelines with the audience.