"While private passenger vehicles contribute 90% of the mileage in the U.S. transportation sector, their emissions share is only 58%. The remaining emissions come from public transit (27%) and other modes including airplanes (13%)."
Diving in, that research is less against public transport in general, more about how the US is just not very good at it:
Our measure of environmental performance is a transit agency's average carbon dioxide emissions per passenger-mile or vehicle-mile.
During the period of analysis, the sector's carbon dioxide emissions declined by 12.8%, while vehicle-miles travelled increased by 7.1% and passenger-miles increased by 10.5%.
Thus, the emissions intensity of public transit has shrunk since 2002 using both measures.
Yet, compared with public transit emissions in the United Kingdom and Germany, we document that the U.S. bus fleets had the highest carbon emissions per mile and the smallest efficiency progress.
ie. US public transport was inefficient and polluting to begin with, and while it improved somewhat when a prior administration finally applied some funding to the task, US public transport stills woefully lags in comparison about the glone.
