Frequently Asked Questions (C-ITS)
This section provides answers to frequently asked questions about Cooperative Intelligent Transport Systems and Services (C-ITS), their deployment in Europe, and the role of the CAR 2 CAR Communication Consortium.
It is intended to give a clear and structured overview for a broad audience, including policymakers, industry stakeholders, infrastructure operators and technical readers.
The explanations focus on the principles behind C-ITS, including system operation, interoperability, security and deployment. Where relevant, they distinguish between:
- European and international standards, which define the technical foundations of C-ITS; and
- deployment specifications and implementation profiles, which ensure that these standards are applied consistently in real-world systems.
The CAR 2 CAR Communication Consortium plays a central role in enabling interoperable deployment by developing these deployment specifications and supporting their consistent implementation across vehicles and infrastructure throughout Europe.
This FAQ is organised into the following sections:
- General & C-ITS Fundamentals
- Interoperability & Standards
- BSP & Deployment Specifications
- Security & Trust
- Testing & Deployment
- Membership & Participation
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| Topic | Question | Answer |
|---|---|---|
| 1. General & C-ITS fundamentals | ||
| What is Cooperative Intelligent Transport Systems (C-ITS)? | C-ITS enables vehicles, infrastructure and other road users to exchange information to improve road safety, traffic efficiency and comfort. Communication is cooperative, meaning participants share relevant data such as position, speed or road events to support safer and more predictable driving behaviour. | |
| What is V2X communication? | V2X (Vehicle-to-Everything) refers to communication between vehicles and other entities in the transport system, including other vehicles (V2V), infrastructure (V2I), vulnerable road users (V2P) and networks (V2N). C-ITS uses V2X communication to enable cooperative awareness and coordinated traffic behaviour. | |
| What is the goal of C-ITS deployment in Europe? | The goal is to improve road safety, traffic efficiency and sustainability by enabling interoperable communication between all road users and infrastructure across Europe. | |
| What is the role of the CAR 2 CAR Communication Consortium? | The CAR 2 CAR Communication Consortium brings together vehicle manufacturers, infrastructure equipment manufacturers, suppliers, road operators and public authorities to develop deployment specifications that ensure interoperable C-ITS implementation in Europe. | |
| 2. Interoperability & Standards | ||
| What is interoperability in C-ITS? | Interoperability means that systems developed by different manufacturers and deployed in different countries can communicate securely and reliably with each other without compatibility issues. | |
| Why are standards not sufficient on their own? | European and international standards define technical capabilities and options, but they intentionally allow flexibility in implementation. Without additional harmonisation, this flexibility may lead to differences in implementation that prevent full interoperability. | |
| What is the role of CAR 2 CAR in interoperability? | CAR 2 CAR develops deployment specifications that define how standards are implemented in practice to ensure consistent and interoperable behaviour across systems. | |
| What is the difference between standards and deployment specifications? | Standards define what is technically possible, while deployment specifications define how systems are implemented to ensure interoperability in real-world deployment. | |
| How do standards, legislation and deployment specifications relate? | Deployment specifications are developed based on:
Together, these inputs ensure both technical correctness and real-world applicability. | |
| 3. BSP & Deployment Specifications | ||
| What is the Basic System Profile (BSP)? | The BSP is the core deployment specification framework developed by CAR 2 CAR. It defines harmonised implementation profiles that ensure interoperable C-ITS deployment across Europe. | |
| Is the BSP a single document? | No. The BSP is an umbrella framework consisting of multiple types of specifications, including implementation profiles, interoperability profiles, security implementation specifications, test specifications, and domain-specific profiles. | |
| What is the purpose of the BSP? | The BSP ensures that C-ITS systems developed by different organisations behave consistently and can interoperate across Europe, even if implemented by different manufacturers. | |
| What types of BSP profiles exist? | The BSP framework includes:
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| How does CAR 2 CAR work with C-ROADS? | CAR 2 CAR and C-ROADS collaborate closely to ensure alignment between vehicle-side BSP specifications and roadside infrastructure specifications developed within C-ROADS. This coordination ensures end-to-end interoperability across Europe. | |
| Why are some BSP specifications public and others member-only? | Public specifications support interoperability across the ecosystem. Member participation provides the opportunity to contribute to development, gain early insight into upcoming changes, and help shape future deployment specifications before publication. | |
| 4. Security & Trust | ||
| How is C-ITS communication secured? | C-ITS uses a Public Key Infrastructure (PKI) to ensure message authenticity, integrity and privacy while preventing misuse or tampering. | |
| What is the EU C-ITS trust framework? | The EU C-ITS trust framework defines the production security infrastructure used for secure C-ITS deployment across Europe, including certificate trust management and root authority governance. | |
| What is the Pilot PKI? | The Pilot PKI is a test environment available to CAR 2 CAR members for development and validation of C-ITS implementations before production deployment. It is operated by MICROSEC under the CAR 2 CAR framework and mirrors the structure of the production trust system. | |
| What is the difference between Pilot PKI and production PKI? | The Pilot PKI is used for testing and development. The production PKI (EU CCMS) is used for operational deployment in real traffic environments. | |
| 5. Testing & Deployment | ||
| Why is testing important in C-ITS? | Testing ensures that independently developed systems are interoperable before deployment on public roads. It validates conformance to specifications and verifies real-world communication behaviour. | |
| What are interoperability tests or Plugtests? | These are structured testing activities where different implementations are connected and evaluated to ensure they work together correctly according to BSP and standards. | |
| How does CAR 2 CAR support testing? | CAR 2 CAR develops test specifications and participates in interoperability validation activities to ensure consistent implementation of deployment specifications. | |
| 6. Membership & Participation | ||
| Why should organisations join CAR 2 CAR if specifications are public? | While deployment specifications are publicly available, membership enables organisations to actively participate in their development, contribute expertise, and gain early insight into future evolution. | |
| What are the benefits of membership? | Members can:
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| Who can become a member? | Vehicle manufacturers, infrastructure equipment manufacturers, suppliers, road operators, public authorities and research organisations involved in C-ITS deployment. | |