The causes of transportation problems in cities are far more complex than is commonly believed. Many popular, short-term solutions to problems, when used indiscriminately, can become counterproductive in the long run. Examples include the belief that building more highways will relieve congestion and air pollution; the expectation that construction of one rail transit line will reverse trends or change travel habits in an entire region; and the hope that free market principles can be successfully applied to urban transportation systems through deregulation of public services, despite the fact that these systems have major social and environmental (that is, nonmonetary) impacts.