Traffic congestionTraffic congestion is the level at which transportation system performance is no longer acceptable due to traffic interference. High lane occupancy percentages indicate congested conditions. The U.S. Department of Transportation uses the following scale to define traffic congestion based on lane occupancy:
35% or higher: Stop and Go
22% - 35%: Heavy
15% - 22%: Moderate
0-15%: Wide Open
As the demand for highway travel by Americans continues to grow as population increases so does traffic congestion. Construction of new highway capacity to accommodate this growth in travel has not kept pace. Between 1980 and 1999, route miles of highways increased 1.5 percent while vehicle miles of travel increased 76 percent.
The Texas Transportation Institute estimates that, in 2000, the 75 largest metropolitan areas experienced 3.6 billion vehicle-hours of delay, resulting in 21.6 billion liters (5.7 billion gallons) in wasted fuel and $67.5 billion in lost productivity. And traffic volumes are projected to continue to grow. Typically, traffic congestion is viewed as a big city problem, but delays are becoming growingly common in smaller cities and even in rural areas.
The five areas showing the highest congestion levels were: Los Angeles (1.57), Washington, D.C (1.43), Miami-Hialeah (1.34), Chicago (1.34) and San Francisco-Oakland (1.33). Cities with the lowest congestion levels were: Bakersfield, Calif. (0.68), Laredo, Texas (0.73), Colorado Springs, Colo. (0.74), Beaumont, Texas (0.76), and Corpus Christi, Texas (0.78). While San Diego and Las Vegas saw their congestion levels increase by more than 50 percent since 1982, conditions worsened at the same rate in three smaller cities: Salt Lake City, Utah, Albany-Schenectady-Troy, N.Y., and Eugene-Springfield, Ore.