Traffic is a headache, and not just for drivers. Jammed roads have become an increasing economic, health and environmental menace to societies, contributing every year to millions of premature deaths and costing vast sums in lost productivity (an estimated $87 billion in the U.S. alone). To policy makers, that's raised the allure of an option that not only can de-clog the streets and improve the air but also fill the coffers. Might congestion pricing become the norm for cities?