A study of highway use says that on two short stretches of expressway in Philadelphia, delays of 1 million hours a year cost $22 million in lost time and waste 375,700 gallons of fuel.

What is the externality described in the news clip? How could road tolls and high parking levies reduce congestion on Philadelphia roads? If road tolls and parking charges cut commute times, would the Philadelphia road system be more efficient? Explain your answers.