ISO/TS 17426:2016 -规定了上下文速度信息服务，即关于提供上下文速度信息服务、支持服务的数据流和服务结果表示的一般要求， -指定上下文速度信息服务要满足的要求， -指定实例化上下文速度信息服务所需的车辆ITS站、路边ITS站、中央ITS站和个人ITS站的ITS站（ITS-S）应用程序流程， -使用ISO 17423中定义的方法指定一组通信要求和目标（概要），以选择其站点之间每个上下文速度信息服务通信流的性能水平（尽力或实时等）、可信度和安全性（认证、加密等）， -选择ITS车站设施层提供的相关功能和程序（见ISO 17429），以及 -指定上下文速度信息服务要使用的消息、消息集结构、内容和语法。 ISO/TS 17426:2016考虑了将相关速度信息从基础设施/路边传输至车辆的情况，以便向车辆驾驶员进一步演示。这种情况下，可以预见相关速度信息的计算是在基础设施方面进行的，而不是在车辆内部。 强制性速度限制或建议速度是相关速度信息服务的输出，该服务（在本技术规范中考虑的情况下）由道路运营商在其交通控制中心或类似基础设施（如路边its站）运行。要通过空中（无线通信）将此信息传输到车辆（以及驾驶员），需要定义的消息。 本技术规范中规定了这些信息。 当相关速度信息到达车辆时，可能需要进一步的预处理，然后才能向驾驶员提供相关速度信息，以及关于速度限制或建议的其他解释（如果可用）。本技术规范规定了处理信息时需要满足的要求。它没有指定车辆如何处理传入的信息。 本技术规范不包括支持本申请的信息的制作、鉴定及其相关性。 ISO/TS 17426:2016阐述了用例1“为驾驶员意识目的向车辆提供强制限速信息”和用例2“为驾驶员意识目的向车辆提供建议速度信息”。

ISO/TS 17426:2016 - 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. ISO/TS 17426:2016 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. Mandatory speed limits or advisory speed recommendations are output of the Contextual Speed Information Service which (in the scenario considered in this Technical Specification) is run by the Road Operator in its Traffic Control Centre or comparable infrastructure (e.g. Roadside ITS Station). To transfer this information to the vehicle (and therefore the driver) over the air (wireless communication), defined messages are required. These messages are specified in this Technical Specification. When Contextual Speed information arrives in the vehicle, further pre-processing might be necessary before the Contextual Speed information, and, if available, additional explanations on speed limits or recommendations, can be presented to the driver. This Technical Specification specifies the requirements that need to be fulfilled when processing the messages. It does not specify how the vehicle handles the incoming messages. The production of information supporting this application, its qualification and its relevance are out of the scope of this Technical Specification. ISO/TS 17426:2016 addresses Use Case 1 "Provision of mandatory speed limit information into vehicle?for driver awareness purposes" and Use Case 2 "Provision of advisory speed information into vehicle?for driver awareness purposes".