## 6 Conclusions  
This study proposes an innovative and unique vibration barrier to mitigate the impacts of vibrations caused by environmental factors. To evaluate the performance of this low-cost wave barrier, which is easily constructed using low-impedance, environmentally friendly, and recyclable materials such as corrugated cardboard and balsa wood, a series of full-scale field experiments were conducted. To determine the barrier's resistance to loads arising from lateral soil stability, three-point bending tests were carried out in a laboratory setting. Additionally, the barrier's durability against environmental conditions at the test site, particularly the effects of groundwater, was ensured through the application of insulation. As an alternative to open trench isolation, this wave barrier aims to reduce ground vibrations generated by human-made sources. With an impedance close to that of a void, the BCCB Trench provides effective vibration isolation without disrupting wave refraction mechanisms. The high modulus of balsa wood and the internal reinforcement design allow the barrier to withstand lateral soil pressure, preventing stability issues in soft soil. Therefore, the BCCB Trench offers robust lateral support while providing isolation comparable to traditional open trenches, demonstrating that low-impedance models are viable alternatives in vibration isolation applications. Furthermore, to investigate the impact of low-impedance waste materials on the wave barrier's vibration isolation performance, the BCCB Trench was filled with very low-density waste polystyrene foam (Styrofoam). The barrier's vibration reduction performance was analyzed by calculating the Amplitude Reduction Ratio values derived from the spectral magnitudes obtained from accelerometers placed behind and in front of the barrier in the direction of vibration propagation from the load source. The measurement metric used to examine the barrier's vibration reduction performance was the ARR value, calculated with PGA values in the primary vibration direction (NS). It was found that the BCCB Trench and the Styrofoam-filled BCCB Trench demonstrated vibration isolation performance comparable to that of an empty trench, with a reduction performance of approximately 88%, placing them within the effective isolation region suggested by [PERSON]. Additionally, the barrier showed successful vibration isolation properties in terms of both PGV and PGD magnitudes. In the conditions of Empty Trench, BCCB Trench, and Styrofoam-filled BCCB Trench, the PGVARR values for the accelerometer located immediately behind the barrier were found to be 0.14, 0.22, and 0.18, respectively, indicating that these values fall within [PERSON] effective isolation region. Additionally, when examining Vibration Mitigation Performance (VMP), it was observed that placing the BCCB Trench in an empty trench only reduced the vibration mitigation performance by 8%. This demonstrates that the BCCB Trench is a viable alternative to an empty trench as a vibration isolation tool. In summary, the newly developed barrier performs within the effective isolation region proposed by [PERSON], making it a viable alternative to other barriers for practical or field applications. Examining the data from the accelerometer placed directly in front of the barrier reveals that, with the presence of the BCCB Trench, vibration amplitudes increased by approximately 30% compared to the No Trench condition, due to the combination of reflected and incoming vibration waves. In contrast, the Styrofoam-filled BCCB Trench showed an increase of only 15%. These results indicate that the internal filler material increased the vibration amplitudes in front of the barrier less than the BCCB Trench condition, thereby demonstrating that the Styrofoam-filled BCCB Trench exhibits superior performance.