This Innovations Deserving Exploratory Analysis (IDEA) project investigated the feasibility of a robotic signaling device to replace the flagman. Rail vibration technology would be used to detect the presence and speed of trains approaching track maintenance work zones. The robot would be designed to place and remove the trip staff, and would be under the control of the track maintenance foreman by means of a hand-held device with a radio frequency link to the robot. The primary objective was to determine whether rail vibration technology could be used to detect the presence and speed of trains approaching track maintenance work zones. Analysis of the acoustic signature data generated by approaching trains revealed that it was difficult to distinguish between trains and background noise. Moreover, the signatures could likely not be detected far enough down the track to provide adequate warning to track maintenance crews, particularly in territory with high-speed train operations. Consequently, fabrication and testing of a prototype was not undertaken. This Stage 1 report documents the design of the prototype, and the Progress Report in the Appendix summarizes the results of the rail vibration analysis.