•Subjects initiated braking significant earlier in the field than in driving simulator.•Subjects in driving simulator showed significantly higher speed and braked distinctly more intensively than in the field.•In driving simulator, the subjects appeared to have reduced risk awareness.•Caution is required when using a driving simulator for designing intersection assistance systems. Introduction: The majority of accidents involving personal injury occur in urban intersections. As human error is the primary cause of these accidents, it seems reasonable to support drivers by intersection assistants. Studies to evaluate such systems are usually performed in driving simulators. However, this implies driver behaviour validity, which cannot always be taken for granted due to the artificial nature of simulated environments. The paper pays special attention to the validity of braking behaviour in urban intersections. In particular, the effect of the test scenario and selected driving simulator design parameters is considered. Method: The Time to Intersection (TTI) time interval between field and simulator study was evaluated at five simple urban intersections. Results: Independently of the type of intersection and the parameter configuration of the simulator, subjects initiated braking in preparation for a turning manoeuvre significantly earlier in the field than in the driving simulator. In particular, the results of both tests differed more at intersections where the driver did not have right of way than at intersections with other layouts, confirming the impact of the test scenario. Some differences were also found when the driving simulator parameter set was varied. Conclusions: The braking behaviour near urban intersections differs between real and simulated experimental environments. From these results, we conclude that caution is required when designing intersection assistance systems based solely on the braking behaviour of subjects in simulated environments. The test scenario and the design parameters must be considered as factors which influence the results. Practical applications: Depending on the current traffic situation and interactions, multiple different kinds of accident can occur at the considered types of intersection, meaning that closely investigating the driver behaviour validity at these junctions is highly important for further intersection assistance systems. Validity of TTI is for example important when determining the best choice of warning interval for a turning assistance system.