The developments in urban rail transit (URT) construction are associated with the benefits of moving people efficiently and the negative impacts of noise and vibrations caused to surroundings. Despite a proliferation of studies conducted throughout the world, very few studies employed the field measurement approach due to various limitations. Using a metropolitan city, Tianjin (China), as an example, field measurement was set up to monitor the indoor vibration and noise spectrum in buildings near urban rapid transit lines to establish a baseline as well as the effectiveness of corresponding mitigation measures, namely wheel-rail polishing and train speed reduction. While our study suggests a maximum 6 dB reduction in indoor vibration, the effectiveness of noise and vibration reduction measures depends on the attenuation of the main frequency corresponding to the secondary radiation noise of the indoor vibration excitation in the building. In our field test, the peaks of the frequency spectrum were found to be 40, 50, 63 and 80 Hz. The secondary radiation noise attenuation and vibration were invariant to the change in frequency spectrum. Mitigation measures such as polishing may cause vibration frequency to peak in non-main frequency spectrums. URT speed reduction will lead to vibration and noise attenuation energy being concentrated at around 50 Hz. Given the presently inconsistent and widely varying industrial and international standards, this study can provide important field measurement data supporting future development in standards, regulation and legislation with respect to URT development, especially in mature townships.

Light pollution from the use of artificial lighting poses significant impacts on human health, traffic safety, ecological environment, astronomy, and energy use. The advancement of characteristics of light pollution assessment technology has played a significant role in shaping prevention and control policies, thereby enabling measures, such as environmental standards and legislation and product procurement guidelines, but considerable variation in the definition, control strategies, and regulatory frameworks remains. Therefore, there is a need to review the characteristics of light pollution, including the assessment technique, policy, and legislation. Through the literature review, it can be found that technical standards are required to prevent light pollution. For example, light pollution is decreased by 6% in France through the legislation of artificial light. Key approaches are suggested to control global light pollution, including implementing ambient brightness zoning, regulating lighting product usage, and establishing dark sky reserves. Technology and policy should be integrated. The precise data coming from satellite imagery, drones, and balloons could provide guidance when making the policies.

Substation noise is a crucial factor that influences residents’ quality of life, especially in the densely residential areas. Despite small- and medium-sized transformer facilities having relatively low noise levels, due to their proximity to residential areas, they generate considerable annoyance, rendering them a focal point among environmental noise complaints. The predominant noise emitted by these facilities falls within the medium- and low-frequency spectrum range, and the conventional passive noise reduction techniques exhibit limited efficacy in attenuating such low-frequency noise. This study develops a real-time active noise control (ANC) system based on a digital signal processor, TMS320F28335, and various ANC methods, including Filtered-X Least Mean Squares (FxLMS), Normalized Filter-X Least Mean Squares (FxNLMS), and variable step-size FxLMS (VS-FxLMS), are evaluated for the low-frequency noise reduction. In addition, the substation noises at a residential community are measured, analyzed, and used as noise source together with a series of sinusoidal waves for evaluation of the ANC algorithms. Results show the ANC system are effective in attenuating most low-frequency noises (within 600 Hz) and the average noise reduction for the substation noises has achieved by more than 12 dB.