Discipline: Technology and Engineering
Subcategory: Environmental Engineering
Qing Li - Texas Southern University
Co-Author(s): Fengxiang Qiao and Lei Yu, Texas Southern University, Houston, TX
On the environmental impacts of transportation, most of the focuses are in vehicle air pollution and the change in landscape with less attention on noise emissions. According to World Health Organization (WHO), 70 dB(A) is a maximum safe noise level for human being without harmful effects for 24 hours exposure. When the noise is greater than 85 dB(A), permanent damage to hearing sensitivity may cause, and even induce hearing loss. With regard to this, the hypothesis of this research is that, the risk of traffic noises to roadside neighborhood and in-vehicle drivers and passengers can be accessed through proper tests and evaluations, with suitable countermeasures proposed accordingly.
The method includes four steps: (1) field tests of noises on roadsides and inside vehicles; (2) Statistical process of different types of noises; (3) access risks of noises from each test; and (4) proposal of suitable recommendations.
Three cases studies were conducted. The impacts of freeway I-30 traffic noises in a neighborhood in Dallas, Texas. Noises were first measured during non-peak hours. Three buffering scenarios (green zone, acoustic walls, and the hybrid) were tested, and significant tests were conducted on the hazard quotient (HQ) for 70 dB(A) and 85 dB(A). Besides, in-vehicle noises on an arterial road in El Paso, Texas, and on freeway I-69 in Houston, Texas during non-peak hours were tested. The hazard exposure rates of 70 dB(A) were accessed. For the first case study with three buffering scenarios (the acoustic wall, green zone, and hybrid), the hybrid one worked the most effective to significantly mitigate traffic noises, with an insertion loss up to 8.06 dB. For the in-vehicle noises, a measurement of 70dB above was often observed on both highways. To utilize asphalts pavement can significantly reduce the in-vehicle noises by approximately 6 dB(A) at the driving speed of 60 mph.
It is concluded that traffic is a crucial source of noise emissions for drivers and neighborhood. The measured ambient traffic noise in the neighborhood and in-vehicle noises often reach the hazard level of 70 dB(A), and even 85 dB(A). The hybrid transparent sound wall and green buffer could significantly improve the situation, whereas more effects are needed to reduce in-vehicle noises. More tests are recommended for in-vehicle noises at different Levels Of Service (LOS) of traffic operations.Not Submitted
Funder Acknowledgement(s): The authors acknowledge that this research is supported in part by the National Science Foundation (NSF) under CREST program #1137732, and the United States Tier 1 University Transportation Center TranLIVE # DTRT12GUTC17/ KLK900-SB-003. The opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the funding agencies.
Faculty Advisor: Fengxiang Qiao, firstname.lastname@example.org