Basic aim of work is to investigate the behavior of radio channels under the freight train. Measurements are performed in different environments; anechoic chamber, free field, car parking area and under the freight train and to see the influence of train metal environment on the channel characteristics. Three different ISM frequency bands; 434 MHz, 868 MHz and 2.4 GHz are used for the measurements to see which band is appropriate for the train environment.Transmitting and receiving antennas are separated at different distances in meters and power of the received signal is measured at the receiver side with spectrum analyzer. On the basis of these measurements, a path loss model is designed, for each frequency band measured, which provides the mathematical and graphical description of measurements. The investigation shows that 2.4 GHz Band gives better results than 434 MHz and 868 MHz for wireless communication system under trains.