Alignment design is an essential procedure in the design process of a rail transit project. It is valuable to study the optimization method of rail transit alignment and realize it through an interactive design system as the investment scale and environmental impacts are closely related to the alignment scheme. In Sect. 1.2, the development of the business interactive design systems of rail transit and highway alignments and the technique demand of alignment optimization system are analyzed. Afterward, we conduct a literature review about optimization models of rail transit and highway alignments from 1968 to 2023. Through the development analysis of alignment optimization models, we introduce some further study requirements of alignment optimization models and present the purpose and content of this book.