U.S. Future Traffic Congestion and Capacity Needs

This paper, a summary of a recent large national study of urban congestion prepared for the Reason Foundation, forecasts the magnitude of US traffic congestion after the completion of long range plans and estimates the cost of its removal through the provision of additional highway capacity. With the help of 32 participating urbanized areas, the study uses equilibrium traffic assignment to determine how much additional capacity will be needed to relieve severe congestion after the regions’ long-range plans are completed. The study extends these findings to all 403 US urbanized areas using meta-modeling of the results from the initial 32 cities and then estimates the cost of providing the additional capacity needed to deal with that remaining congestion. The paper finds that severe congestion is pervasive in large regions and is worsening throughout the US. The cause of this increase is not wastefulness but increasing population and limited road capacity. Nationwide, lane-miles of severely congested roads will increase from 39,500 in 2003 to 59,700 in 2030. To relieve severe congestion an additional 104,000 lane-miles (about 6.2 percent of current lane-miles) will be needed costing about $ 533 billion over 25 years, or about $21 billion per year. This is about 10-15 percent of the US highway program, 28 percent of the cost of present urban transportation plans, and 39 cents per day per commuter trip. Travel time savings are estimated at about 7.7 billion hours annually so the cost per hour of delay saved is about $2.76.