By Robert Krol
Each year, state and local governments decide on which transportation infrastructure projects to build. Often, priority goes to projects directed at reducing highway congestion or air pollution.
The economic backbone of the decision process is supposed to be an objective cost-benefit analysis. However, calculating the costs and benefits of any major project is technically difficult.
Cost estimates require a determination of labor and material quantities and prices.
Benefit estimates require forecasting economic growth, demographic trends, and travel patterns in the region.
Clouding the analysis is the fact that this decision process takes place in a political environment. Politicians love the publicity they get at the opening of a high-occupancy vehicle lane or the expansion of a mass…