## 2 Background
### The Simulation Context
The existing roadside stations are to be upgraded according to the newest C-Roads profiles, and RSUs will be available every 5 km of the expressway in the coming development phase. Figure 1: Roadside Units along Expressway M0. Despite the tremendous results already collected with the help of the C-Roads Platform, technological innovation still causes plenty of challenges for road operators. It leaves many uncertainties for C-ITS and even more for CCAM (Connected, Cooperative, and Automated Mobility). To tackle the difficulties, Hungarian Public Roads further support connected mobility. The ongoing deployments involving a national C-ITS infrastructure and a planned European C-ITS ecosystem also help this goal by providing more valuable information, best practices, and harmonization guidelines. An essential part of these C-ITS-related investments in Hungary is connected to the Automated Proving Ground and ZalaZone [47], which is dedicated to genuine public road testing in the town of Zalaegerszeg. The test track is unique because it integrates all the standard driving and driving stability features, a complex research/development framework, and advanced communication infrastructures to create a multi-level system for validating automotive solutions for the CCAM era. Therefore, the proving ground provides dynamics tests for conventional vehicles, but it also allows validation tests for autonomous and electric vehicles. The demand was raised by setting up the test track to enable open road tests (with safety always the first concern). In addition to the testing area of ZalaZone, the planned expressway M76 (between M7 and Zalaegerszeg) will be a part of the testing facility, too. This is the first road section in Hungary that will be constructed by taking the requirements of automotive Tier 1 s and OEMs into account already from the planning phase and aiming at CCAM test opportunities in real traffic conditions. The ongoing C-Roads 2 Hungary project is focusing on this region, too, using synergies with the test facility. The planned Hungarian work program devotes particular attention to creating an urban test environment for autonomous and connected vehicles in the town of Zalaegerszeg, linked to the Automotive Proving Ground Zala (APZ), and building on the experiences of the pilot project in Gyor. The deployment will focus on Day1 and Day1.5 C-ITS services with special attention on Vulnerable Road User (VRU) use cases. \"ZalaZone\" is the greater area that includes the town and the test track that will be ready for autonomous vehicle testing, but there are even more ambitious plans. As part of trilateral multi-level cooperation, Austria, Slovenia, and Hungary plan to implement cross-border test routes [48]. C-Roads 2 Hungary will enhance this effort by implementing C-ITS services in the greater city area and TEN-T corridors (with domestic and cross-border sections). Supported by the C-Roads Platform results/available deployment details and driven by the above-introduced intertwined C-ITS/CCAM plans of the Hungarian road operator, it became essential to start analyzing the possible limitations of existing infrastructure components and to evaluate potential barriers and challenges to the further growth and advancement of C-ITS solutions available. This work can be considered as the first step of this general effort. We took expressway M0 and its RSU deployment as the C-ITS infrastructure under evaluation: we modeled the traffic of this road segment based on real-life traffic and map data, we modeled the RSU deployment and the V2X network and performed extensive simulations to highlight how the penetration rate of the C-Roads-compatible V2X technology will affect the service scalability in means of the radio channel load from now to the future.