I'm confused as well.
The Brookings Institution compared the 100 largest U.S. metro areas for the number of households with no cars and no access to transit. It then ranked them based on how effectively its public transit system gets residents to work.
I must be reading this wrong, but it appears to be saying they ranked the number of households with no access to transit, based on how effectively the transit system moved those citizens. If they don't have access to public transit, then how can they rank how well transit transports them? Unless by "transit" they simply mean any form of non-public transit? If that's the case then they need to choose different words.