A methodology has been developed for the use of microscopic traffic simulation modelling for the investigation of road safety impact from the introduction of two advanced driver assistance systems (ADAS).  The simulations modelled key parameters (headway, speed) for several scenarios of different traffic levels and assumed penetration levels of Adaptive Cruise Control and Intelligent Speed Adaptation systems. Results from the simulations, studied in the context of existing relationships between the number of road accidents and traffic parameters, allowed the estimation of the related traffic safety impact. This impact was investigated in relation to the corresponding changes in average speed, in headways, in time-to-collision and in lane changing.  Even though an overall straightforward answer to the safety impact of ADAS systems was not possible due to the complexity of the traffic safety phenomenon, several positive effects on safety were identified.