That's the question so many ask about light rail. If it fails to, for example, improve mobility, why are so many cities building rail lines? It's a good question and the Federal Reserve of St. Louis has a part of the answer:
If light rail is not cost-efficient, nor an effective way to reduce pollution and traffic congestion, nor the least costly means of providing transportation to the poor, why do voters continue to approve new taxes for the construction and expansion of light-rail systems?
One economic reason is that the benefits of light rail are highly concentrated, while the costs are widely dispersed. The direct benefits of a light-rail project can be quite large for a relatively small group of people, such as elected officials, environmental groups, labor organizations, engineering and architectural firms, developers and regional businesses, which often campaign vigorously for the passage of light-rail funding. These groups would benefit from light rail, not from the subsidization of cars and money to all potential riders of light rail.
The costs of light rail, while large in aggregate, are often small when spread over the tax-paying population. (The cost of light rail in St. Louis totals about $6 per taxpayer annually). A large group of taxpayers facing relatively minimal costs can be persuaded to vote for light rail based on benefits shaped by the interested minority, such as helping the poor, reducing congestion and pollution, and fostering development. Even if these benefits are exaggerated and the taxpayer realizes the cost-ineffectiveness of light rail, it is probably not worth the $6 for that person to spend significant time lobbying against light rail.
The study goes on to make a point that has been made before. It would be better to buy cars for the transit dependent poor:
Based solely on dollar cost, the annual light-rail subsidies could instead be used to buy an environmentally friendly hybrid Toyota Prius every five years for each poor rider and even to pay annual maintenance costs of $6,000. Increases in pollution would be minimal with the hybrid vehicle, and 7,700 new vehicles on the roadway would result in only a 0.5 percent increase in traffic congestion. And there would still be funds left overâ€“about $49 million per year. These funds could be given to all other MetroLink riders (amounting to roughly $1,045 per person per year) and be used for cab fare, bus fare, etc.