Traffic safety applications relying on cooperative systems are currently being considered by several research projects worldwide. An important question is if existing wireless technologies can meet the communication requirements from this emerging field ofvapplications? Part of the answer to the question is that the communication requirements depend on implementation. The data traffic from realizations based on “cooperative awareness” or on “hazard warnings” are very different. This article discusses the communication requirements of some typical traffic safety applications, how these requirements are affected by different realizations and finally what is required from a wireless access technology to support these applications.