The human factor guidelines aim to improve road safety by enabling the safe use of traffic information services while driving. For this, the report contains the key human factor and ergonomic criteria which support in-car traffic service providers with taking into account the abilities and capabilities of drivers. Designers get practical support to develop safe in-car traffic information services. Authorities who commission the development of traffic information services, are supported in specifying tenders and checking project proposals. The human factor guidelines are a living document that will be updated from time to time based on experience with new technologies and new research.