With the advance in electromagnetic techniques, measuring and monitoring the moisture content in pavement systems appears feasible, and the contribution of geosynthetics to the drainage system can be verified. To investigate the performance of a geocomposite membrane (a low-modulus polyvinyl chloride layer sandwiched between two nonwoven geotextiles), two sections at the Virginia Smart Road were instrumented and constructed to quantify the effectiveness of the geocomposite membrane as a moisture barrier and as a strain energy absorber. All layers were instrumented for stress and strain measurements as well as for environmental effects (temperature, frost, and moisture). The moisture variation in the subbase aggregate layer over different precipitations was continuously monitored by using time domain reflectometry (TDR). Ground penetrating radar (GPR) was used periodically to monitor water movement in the pavement sections. Results of the GPR surveys indicated that use of a geocomposite membrane underneath a drainage layer forms a water barrier, preventing the saturation of underlying layers and facilitating the lateral drain of water. Results of TDR moisture sensors validated the effectiveness of the geocomposite membrane in abating water infiltration into the subbase layer even in the event of heavy rain.