Air quality inside an underground road tunnel system

• Main Author: Lin, Jiang Xun.
• Other Authors: Chang Wei-Chung
• Format: Final Year Project
• Language: English
• Published: 2010
• Subjects: DRNTU::Engineering::Environmental engineering::Environmental pollution
• Online Access: http://hdl.handle.net/10356/39601
• Institution: Nanyang Technological University

This study is based on 3 days of constant air quality monitoring with the use of 2 self improvised monitoring devices. The purpose of the study is to draw comparison from the sensors in a latest constructed road tunnel with the measured data from the monitoring devices to ensure the accuracy of the ventilation system sensors. The monitoring devices were situated in the South-bound tunnel as it was presumed that the traffic conditions during the morning hours were unfavourable to road users. The morning hours was identified as the peak period with the highest volume of road users and vehicular emission. Hence the motorist would experience low visibility and more exposure to the poor air quality, and this was also the objective of the investigation. Since the newly constructed underground road tunnel was opened to traffic in September 2008, mainly light duty vehicles have been allowed to pass it due to safety precautions. Although the road tunnel carries primarily light duty vehicles, the vehicular emissions still pose a threat to air quality and human health. In addition to the verification of the accuracy of the tunnel sensors, vehicular emissions were measured to identify the characteristics of gaseous pollutants. The vehicular emissions consisting of CO, temperature and particulate matter were monitored for a continuous period of 3 days. The volatile organic compound was monitored on a peak and off-peak session whereas the SO2 was monitored only on a single peak session on the first and second day. The results of the study have shown that the measured temperature from the measuring devices is higher than the tunnel sensors result. There is a higher average temperature on a weekday than weekend. Generally, there is correlation between the temperature profile, traffic volume and particulate concentration established as well. The visibility level in the tunnel is also likely to be influenced by the particulate concentration PM2.5 based on the course of the study. In addition, the carbon monoxide level is found to be proportional to the traffic counts as it peaks approximately at the same rate and period as the traffic volume. The results of the sulphur dioxide concentrations also show a moderate relation with the particulate matter and carbon monoxide. Finally, the study on the volatile organic compounds also reflects a correlation with its concentration and traffic volume.