It is important to predict characteristics of radio wave propagation. The pathloss characteristic has close correlation with coverage and layout of a radio system. The timedelay characteristic determines the maximum transmission rate of a radio digital system. In this paper, a new model is presented to predict wave propagation in rectangular tunnels with a rectangular section. In an rectangular tunnel, paths between transmitter and receiver can be determined analytically using geometric optics. The method avoids complicated ray tracing calculation. From the simulation results, accuracy of the prediction is better than ray tracing. The less the separation between transmitter and receiver, the larger the root mean square (RMS) delay spread and mean excess delay. The larger the dimension of cross section, the larger the RMS delay spread and the mean excess delay. 