Urban Transportation Has Supply and Demand

The supply is the built infrastructure (e.g., streets, overpasses, highways, and parking lots) to accommodate an increasing number of person-trips or person-miles traveled (demand). 

To meet the growing demands of commuters, most cities first try to expand the infrastructure, but many are now:

• Running out of space
• Suffering from health problems related to air pollution due to auto exhaust
• Finding their city centers and neighborhoods disrupted by cars and roads and no longer walkable or livable
• Increasing housing costs due to off-street parking requirements
• Fostering car trips due to free on-street parking
• Paying exorbitant costs for transport-related issues. In some cases, more than 10 percent of a country’s GDP is lost due to wasted time, traffic fatalities, and other things…(Dalkman, H. & Sakamoto, K., 2012)
• And yet they are still unable to provide high-quality transportation.