Infrastructure-assisted Cooperative Intelligent Transportation Systems (C-ITS) leverage roadside intelligent infrastructure and vehicular network technology to facilitate information exchange among traffic participants, enhancing road safety, efficiency, and sustainability. However, this requires not only the massive deployment of infrastructure, including advanced sensors, communication devices, and computing units at various levels, but also the involvement of various stakeholders in the development of functions and real-road testing. In this paper, we present our test field -- \myTestField, as an \emph{open innovation lab} for C-ITS in Ingolstadt, Germany, offering an open environment for world-wide stakeholders to conduct research and testing in C-ITS. In particular, we equip a 3.5 km area with 22 roadside intelligent masts and 89 sensors, achieving dense deployment on public roads. Our design includes a protocol stack tailored for different C-ITS stations and services, conforming to European communication standards. Furthermore, we conduct quantitative analyzes of key performance metrics, such as radio signal quality and End-to-End delay, to assess the efficacy of \myTestField in different data processing pipelines. Finally, we delve into the future prospects of large-scale C-ITS deployment, guided by extensive and prolonged measurement studies.     «

Infrastructure-assisted Cooperative Intelligent Transportation Systems (C-ITS) leverage roadside intelligent infrastructure and vehicular network technology to facilitate information exchange among traffic participants, enhancing road safety, efficiency, and sustainability. However, this requires not only the massive deployment of infrastructure, including advanced sensors, communication devices, and computing units at various levels, but also the involvement of various stakeholders in the devel...     »