Traffic congestion is growing across the nation in cities of all sizes, according to 20-year trends in a new report released Tuesday. The 2004 Urban Mobility Report, published by the Texas Transportation Institute (TTI), shows traffic consuming more hours of the day, and affecting more travelers and shipments of goods than ever before. More of the same is expected, said the study's authors. "We can see pretty clearly what 20 years of almost continuous economic growth can do to us," said Tim Lomax, one of the study's authors. "If we are lucky enough to sustain this growth and the funding levels and options do not increase from current trends, we shouldn't be surprised if we see even more congestion." Among its conclusions, the TTI study found that the average annual delay time per peak period traveler climbed from 16 hours in 1982 to 46 hours in 2002. Southern California's traffic jams ranked the worst in the nation for the 18th consecutive year. Commuters in Los Angeles, Orange and parts of Ventura counties waste an average of 93 hours a year idling in gridlock. The cost of congestion in 85 major U.S. urban areas in 2002 totaled more than $63 billion. Between 1982 and 2002, the study found that travel time saved because of public transportation increased four-fold. The report also measures the mobility-improving contributions of public transportation service and techniques to improve roadway operating efficiency. In 2002, regular bus and train services in America’s most congested cities saved travelers 1.1 billion hours in travel time. Without public transportation, nationwide travel delays would have increased by 32%, costing residents in the major urban areas studied an additional $20 billion in lost time and fuel.