This paper attempts to analyze the behavior of a radio signal inside a partially open drain environment using the empirical approach. The proposed research topic concerns a unique situation in several Asian countries, because the drainage systems in these countries differ notably from those in the US and Europe, in that the former are partially open on the top while the latter are primarily below ground and covered. A series of measurements at 900 MHz, 2.4 GHz, and 5.8 GHz have been conducted inside one drain, as well as on the ground next to the drain, located on the Sunway University campus. The differences between the measurement results at the three frequencies are discussed, along with the measurement results collected from the ground next to the drain. Understanding the complicated wave-propagation behavior inside the partially open drain and the ground nearby serves as a useful indicator in designing reliable wireless communication systems, especially in environments where such drains are present. Additionally, knowledge gained from the measurement results will aid in improving the accuracy of radio-propagation prediction, which, in turn, can help in establishing dependable wireless communication networks in urban and other complex propagation environments.