Intermodal comparison of tailpipe emission rates between transit buses and private vehicles for on-road passenger transport

Wei, Tongchuan; Frey, H. Christopher

doi:10.1016/j.atmosenv.2022.119141

Cited by 4 publications

(2 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…On-board portable emission measuring system (PEMS) measurements are designed to measure on-road vehicle emission with real-world driving operations under a wide range of ambient conditions and vehicle mode of operation (e.g., vehicle speed). − Vehicle emissions are commonly characterized in terms of pollutant emission factors (EFs) that are defined as the amount of pollutant emitted per defined task performed (e.g., mass of fuel burned). Calculating EFs with PEMS (EF PEMS ) is considered a reliable method since it is a direct measurement of tailpipe emissions.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of the Relationship between Meteorological Variables and NO_x Emission Factors Based on Plume-Chasing Measurements

Xiang

Zhang

et al. 2023

ACS EST Eng.

View full text Add to dashboard Cite

A relationship that links the accuracy of nitrogen oxide emission factors (NO x EFs) calculated from chasing measurements (EFchasing) to meteorological variables was developed. To quantitatively evaluate this relationship, we postulated an “effective ratio” concept based on the momentum wake theory. The effective ratio is considered a function of meteorological variables in the vehicle wake. A mobile platform was used to characterize NO x EFs by following tested vehicles that were installed with a portable emission measuring system (PEMS) on a restricted driving track. The relationship was evaluated based on 172 plume-chasing measurements that were conducted under various operating scenarios such as different tested vehicle speeds and vehicle types. Two calculation approaches (i.e., baseline vs rolling minimum) were used to calculate EFchasing and benchmark against NO x EF from PEMS (EFPEMS). A consistent positive linear relationship (slope ∼28, p < 0.01) is found between the effective ratio and the relative error of EFchasing under all operating scenarios and is independent of calculation approaches. This is evidence that the effective ratio could be a good parameter that quantifies the relative deviation of EFchasing and is independent of calculation approaches. Based on this relationship, the effective ratio can be further used to identify erroneous chasing measurements and improve the accuracy of EFchasing.

show abstract

Section: Introductionmentioning

confidence: 99%

Evaluation of the Relationship between Meteorological Variables and NO_x Emission Factors Based on Plume-Chasing Measurements

Xiang

Zhang

et al. 2023

ACS EST Eng.

View full text Add to dashboard Cite

show abstract

“…Public buses can be less or more polluting in terms of emissions per PKT than private cars and motorcycles, depending on the occupancy levels and pollutant type. Break-even passenger load has been used by researchers to evaluate emissions per PKT of public buses with those of private modes of transportation [ 30 ]. In the present study, we estimated the break-even occupancy rate defined as the minimum occupancy rate required for the bus so that the bus would be less polluting in terms of emissions per PKT than both the car and motorcycles.…”

Section: Methodsmentioning

confidence: 99%

Effects of the COVID-19 pandemic on public bus occupancy and real-world tailpipe emissions of gaseous pollutants per passenger kilometer traveled

Dhital

Wang

Yang

et al. 2022

Sustain Environ Res

View full text Add to dashboard Cite

Public buses typically have less emission per passenger kilometer traveled (PKT) than private cars and motorcycles, and the emission benefit of public buses increases with ridership. However, the drop in public bus usage during the novel coronavirus (COVID-19) pandemic could lead to an increase in air pollutant emissions per PKT, making the emission benefits of public buses questionable. This study investigated the effects of the COVID-19 pandemic on public bus occupancy rates in Taichung City, Taiwan, and also compared real-world emissions per PKT of carbon monoxide (CO), total hydrocarbons (THC), nitric oxide (NO), and carbon dioxide (CO2) of a public bus before and during the pandemic. Mean bus occupancy rates were 11–25% on different bus routes before the pandemic, indicating that only a fourth or less of the bus passenger capacity was utilized. During the pandemic, mean bus occupancy rates dropped to 4–15%. Moreover, the public bus was less polluting based on CO and THC emissions than the car and motorcycle, even at the low passenger occupancy rates observed during the pandemic. However, NO and CO2 emissions per PKT of the bus were remarkably higher during the pandemic than those of the car and motorcycle. Furthermore, we estimated the break-even passenger occupancy rate for buses as 15%, which was the minimum threshold occupancy rate below which the buses would be more polluting than cars and motorcycles in terms of CO, THC, and CO2 emissions per PKT. Our findings will help transport management authorities and policymakers to optimize bus route designs and frequencies and implement anti-pandemic measures to maximize the environmental benefits of the public bus transit systems.

show abstract

Spatiotemporal analysis of CO2 emissions and emission reduction potential of Beijing buses using smart card data

Zheng,

Huang,

Zhou

et al. 2023

Sustainable Cities and Society

View full text Add to dashboard Cite

Intermodal comparison of tailpipe emission rates between transit buses and private vehicles for on-road passenger transport

Cited by 4 publications

References 20 publications

Evaluation of the Relationship between Meteorological Variables and NO_x Emission Factors Based on Plume-Chasing Measurements

Evaluation of the Relationship between Meteorological Variables and NO_x Emission Factors Based on Plume-Chasing Measurements

Effects of the COVID-19 pandemic on public bus occupancy and real-world tailpipe emissions of gaseous pollutants per passenger kilometer traveled

Spatiotemporal analysis of CO2 emissions and emission reduction potential of Beijing buses using smart card data

Contact Info

Product

Resources

About

Intermodal comparison of tailpipe emission rates between transit buses and private vehicles for on-road passenger transport

Cited by 4 publications

References 20 publications

Evaluation of the Relationship between Meteorological Variables and NOx Emission Factors Based on Plume-Chasing Measurements

Evaluation of the Relationship between Meteorological Variables and NOx Emission Factors Based on Plume-Chasing Measurements

Effects of the COVID-19 pandemic on public bus occupancy and real-world tailpipe emissions of gaseous pollutants per passenger kilometer traveled

Spatiotemporal analysis of CO2 emissions and emission reduction potential of Beijing buses using smart card data

Contact Info

Product

Resources

About

Evaluation of the Relationship between Meteorological Variables and NO_x Emission Factors Based on Plume-Chasing Measurements

Evaluation of the Relationship between Meteorological Variables and NO_x Emission Factors Based on Plume-Chasing Measurements