mass transit – n. a system of large-scale public transportation in a given metropolitan area, typically made up of buses, subways, and elevated trains

congestion – n. a condition on roads that occurs as use increases and is characterized by slower speeds and longer trip times

sacrifice – n. the act of giving up something that you want to keep especially in order to get or do something else or to help someone

gridlock – n. a situation in which streets are so full that vehicles cannot move

sustainable – adj. able to last or continue for a long time