The evaluation of the road markings visibility has been defined according to human needs, but shall now be extended to the needs of vision-based Advanced Assistance Driving Systems (ADAS). Several publications propose minimum levels of daytime or night-time visibility of the road marking and their contrast with the surrounding pavement, to ensure optimum detectability of Machine Vision systems. However, the calculation methodology is rarely indicated (the heterogeneity of the markings is not always taken into account) and very little information about the Machine Vision system is provided. In this study, a daily experiment was conducted on a small dry road section using a mobile retroreflectometer and a vehicle equipped with a Machine Vision system. Several statistical analyses are performed on the collected data at different study scales (punctual or global scale). They show that despite very low levels of marking retroreflection values and visibility contrast ratios, the road marking lines are almost always very well detected by the camera's algorithm. That demonstrates that the current indicators characterizing the marking visibility according to standards are not enough to fully understand the behaviour of Autonomous Vehicle cameras.