As an important Earth observation technology, Interferometric Synthetic Aperture Radar (InSAR) has been widely applied in surface deformation monitoring, such as urban subsidence, mining activities, and geological hazards, owing to its advantages of wide spatial coverage, millimeter-level precision, and long-term temporal observations. In recent years, its applications have extended to the safety monitoring of transportation infrastructure. Roads, railways, bridges, and airports are characterized by wide spatial distribution, linear and elongated structures, dynamic operation, and complex service environments, which pose high demands on conventional monitoring methods. InSAR provides a promising alternative solution. This study focuses on the applications of InSAR in transportation infrastructure monitoring by systematically reviewing research progress and development trends. First, based on current studies, typical applications of InSAR for different types of infrastructure, including roads, railways, bridges, and airports, are summarized to demonstrate its potential in subsidence monitoring, deformation identification, and structural safety assessment. Second, the major challenges of current InSAR applications are outlined by considering the particularities of transportation scenarios. These challenges include insufficient coherence due to weak scattering targets, discontinuous deformation of bridges and similar facilities that violate conventional models, and severe interference of atmospheric turbulence with millimeter-level monitoring precision. Several methodological improvements are discussed to address these challenges. These improvements include phase optimization, localized inversion with external constraints, atmospheric delay modeling, and integration with auxiliary datasets, which collectively enhance the reliability and applicability of InSAR results. Finally, the study incorporates representative application cases from the authors’ team on various types of infrastructure, thereby highlighting the potential of time-series InSAR technology in this field and further outlining future research directions. The application of InSAR technology in transportation infrastructure monitoring has already demonstrated broad prospects; however, continuous methodological and application-oriented improvements are still required to support transportation safety management and risk mitigation adequately.