Do economists reach a conclusion on rail transit?

In the United States, the public debate over urban rail projects is complicated by the lack of agreement on goals. Supporters offer a wide variety of justifications to build and expand rail transit. If one focuses on the judgments of economists, the list of justifications shrinks considerably, but we are still left with a bundle of goals. Compared to other justifications, economists appear to be somewhat optimistic about rail transit’s impact on local economic development, but less optimistic about rail’s ability to achieve environmental improvement and serve the transit-dependent poor. Economists seem quite pessimistic about rail’s ability to achieve key transportation goals like reducing congestion. Economists often attribute rail’s political success to rent-seeking and romantic political factors. Of those economists who offer a big-picture view, there appears to be wide, though not unanimous, agreement that rail’s costs exceed its benefits. And it seems that almost all economists who write about rail agree that various demographic features, such as suburbanization, the declining influence of central business districts, and increasing wealth will make it increasingly difficult to design successful rail systems.