The United States faces growing challenges in maintaining and modernizing transportation infrastructure while addressing workforce shortages and rapidly evolving technologies. Rail transportation, one of the most energy-efficient and sustainable modes of freight and passenger movement, plays a critical role in supporting economic growth, national defense, and environmental sustainability. These challenges highlight the need for engineers equipped with interdisciplinary skills and knowledge of emerging technologies such as artificial intelligence, structural materials, smart sensing systems, and data-driven infrastructure management. This Research Experiences for Undergraduates (REU) Site at The Pennsylvania State University, Altoona will support 10 undergraduate students each year in a 10-week summer research program focused on smart and sustainable transportation infrastructure. Leveraging the nation’s only ABET-accredited bachelor’s degree program in Rail Transportation Engineering (RTE), the program uses rail systems as living laboratories to provide interdisciplinary research experiences spanning civil, mechanical, electrical, computer, and transportation engineering. Participants will work with faculty mentors, industry partners, and researchers affiliated with the Rail Center for Research Enhancing Shortline Transportation (Rail CREST), a federally funded initiative focused on strengthening shortline rail infrastructure and workforce development. Through mentored resear