This study presents the development and pilot application of cementitious materials incorporating microencapsulated phase change materials (PCMs) for thermal regulation in rubber-tired Automated Guideway Transit (AGT) systems. Unlike previous PCM studies limited to buildings, this work demonstrates their first use in railway infrastructure. Material tests confirmed that PCM incorporation increased water and superplasticizer demand and reduced compressive strength, with up to a 36.7% loss at 30% replacement. Despite this trade-off, DSC and dynamic heat flow tests showed stable phase-change behavior and a significant heat-buffering effect, delaying internal temperature rise from 20 to 40 °C by up to 80 min. A pilot-scale test section of the K-AGT system was prepared, in which PCM-incorporated concrete was cast only at the top surface in contact with the wheels. This preliminary field application, the first of its kind in railway infrastructure, demonstrated the feasibility of the localized use of PCM-enhanced materials for addressing heat accumulation.