The severity of accidents resulting in injuries, deaths and property damage has been recognized by the World Health Organization (WHO) as a public health problem. Intelligent transport systems (ITS), based on communication and information technologies, have the potential to improve road safety for all types of road use. This article presents an analysis of ITS and its benefits, as well as the importance of ITS on safety, and explores how ITS can affect all significant changes (e.g., exposure, risk, and severity) of issues of security. In the event of an accident, we study how ITS can affect all important variables such as injuries, risk and severity of the accident, and identify the safety of ITS for road users. Let's compare ITS implementation and ITS effectiveness before and after implementation. Several studies are presented, and road safety related to ITS applications is discussed. This is an attempt to create a state of the art of their impact on thinking by classifying machines according to the level of measurement method used. Since ITS activities are effective in reducing the number of incidents, changes in ITS behaviour are considered and discussed, particularly with regard to the payment process.