Dynamic Scoring in Unusual Places

It may not yet be a staple of federal budget policy, but dynamic scoring has come to the New Hampshire/Massachusetts border. From Friday's Associated Press:

The long-planned expansion of Interstate 93 has been pushed a little further down the road. A federal judge ruled yesterday that before they can move ahead with the project, state and federal highway officials must do more work to study the population growth that would be spurred by the widening itself.

The ruling was a victory for environmentalists who argue that widening the road to four lanes between Manchester and the Massachusetts border would itself cause population growth that will lessen the usefulness of the widening, congest secondary roads and cause air pollution.

Of course, it is only a partial equilibrium analysis. Where does the additional population come from? Does their relocating to southern New Hampshire alleviate traffic problems elsewhere, and should that benefit be considered as well?

On the substance of the case, the Conservation Law Foundation is arguing that the resolution of the traffic problems ought to include commuter rail options. I'm sympathetic to the point. It has always been a bit of a surprise that there is no rail link between Boston and Concord, New Hampshire, given the proximity and the number of commuters who now go by car.