To address the passenger safety concerns related to the recent incidents of inadvertent railcar door opening, this SBIR project develops a low-cost Intelligent Door Operation System (IDOS).By installing small ultrasonic proximity sensors beneath side doors and linking them to the door control circuit, IDOS ensures that doors will not open unless their sensors detect the presence of a platform. The sensors can also measure the distance between the train and the platform edge, which can be developed into a database for machine learning to further improve the detection reliability and robustness. The primary objective of Phase I is to demonstrate the feasibility of IDOS by addressing technical challenges associated with the reliability, robustness, and fault-tolerance of the platform detection. Major Phase I tasks include (1) development of a knowledgebase about passenger trains and platforms, (2) a conceptual design of IDOS,and (3) a proof-of-concept prototype and tests involving a railcar mockup and platform test specimens. The project team has foremost expertise in creating sensor-based technology solutions to challenging problems, as well as experience in railway infrastructure sensing.An advisory board involving end users will be established to ensure the research relevance for successful future commercialization of IDOS.