Gasoline switching locomotive

Abstract

Particulate matter emissions from a large sample (N = 88) of in-use line-haul freight locomotives were measured in the Alameda Corridor, located near the ports of Los Angeles and Long Beach. Emission factors for black carbon (BC), particle number (PN), fine particulate mass (PM2.5), and lung-deposited particle surface area (LDSA) were computed based on 1 Hz measurements of the rise and fall of particulate matter and CO2 concentrations as the locomotives passed the sampling location. We include LDSA emission factors as relevant for near-source human exposures. Mean emission factors ± standard deviations were 0.9 ± 0.5 g kg−1 fuel consumed for BC, (2.1 ± 1.5) × 1016 # kg−1 for PN, 1.6 ± 1.3 g kg−1 for PM2.5, and (2.2 ± 1.7) × 1013 μm2 kg−1 for LDSA. Emission factors for individual trains were slightly skewed, with the dirtiest 10% of trains responsible for 20%, 24%, 28%, and 27% of total BC, PN, PM2.5, and LDSA emissions, respectively. The relative importance of high-emitters is therefore lower for these locomotives relative to previously reported diesel truck emissions. BC versus PN emissions from individual locomotives were found to be anti-correlated, suggesting that the highest emitters of particle numbers are the lowest emitters of black carbon. Using results presented here along with previous measurements, we compared for freight trains versus diesel trucks the amount of BC emissions associated with pulling an intermodal freight container over a given distance. This assumption-dependent comparison showed that in most cases locomotives emit less BC per container hauled than diesel trucks. However, continual decreases in diesel truck BC means that unless emissions from locomotives are decreased in the near future, emissions associated with hauling a container could become lower for diesel trucks than locomotives.