This Technical Specification
— specifies the Contextual Speed Information Service, namely the general requirements regarding the
provision of the Contextual Speed Information Service, the data flow supporting the service, and
the presentation of the service result,
— specifies the requirements to be fulfilled by the Contextual Speed Information Service,
— specifies the ITS Station (ITS-S) application processes of the vehicle ITS station, roadside ITS station,
central ITS station, and personal ITS station that are required to instantiate the Contextual Speed
Information Service,
— specifies sets of communication requirements and objectives (profiles) using the methods defined
in ISO 17423 to select the level of performance (best effort or real-time, etc.), confidence and security
(authentication, encryption, etc.) for each Contextual Speed Information Service communication
flow between ITS stations,
— selects relevant functions and procedures provided by the ITS station facilities layer (see
ISO 17429), and
— specifies messages, messages sets structure, content, and syntax to be used by the Contextual Speed
Information Service.
This Technical Specification considers the scenario for the transmission of Contextual Speed
information from the infrastructure/roadside to the vehicle, for onward presentation to the vehicle’s
driver. This scenario foresees that the calculation of Contextual Speed information is performed on the
Infrastructure side, not within the vehicle.