This paper presents a safe sensing scheme and radio frequency energy harvesting system (RFEHS) to monitor rail conditions for autonomous trains. Conventional sensing schemes expose trains on railroads to danger because trains must pass the rail to know its condition. The proposed sensing scheme gets rid of the danger and reduces the complexity of sensing processes and train systems because trains do not have to communicate directly with sensors. In this sensing scheme, the RFEHS receives dual polarization (DP) signal, which is all of the base station's polarizations so that the sensor operation gets more frequent. The harvesting capability of DP and linear polarization (LP) from a real base station is compared. To prove the feasibility of the proposed sensing scheme, the RF energy harvesting was conducted from a base station on the rail track. As a result, rail temperature data were obtained using DP-RFEHS in the proposed sensing scheme, which has low-complexity and is a safer solution for autonomous trains.