This book focuses on the fundamental ideas in the future smart transportation infrastructure systems that, in turn, give rise to new architectures and applications of emerging technologies. Although the scope of transportation infrastructure systems is very broad, this book focuses in detail on the main one—urban road infrastructure systems. Based on the investigation of the development trend and current situation of the smart road infrastructure (SRI), this book clarifies the connotation, architecture, and implementation path of the SRI. Emerging technologies related to SRI have also been summarized, which is useful for SRI design and construction. The book is intended for undergraduate and graduate students who are interested in the SRI technology or intelligent transportation systems and road/transportation design engineers working on relevant projects.