The average large European urban area has a density of traffic greater than that of America's most congested urban area, Los Angeles. And they don't have the road systems to deal with it.The same thing is true in the United States. Federal research shows that for every 1 percent increase in population density, there is an approximately 0.8 percent increase in vehicle travel. This is already evident in Portland, which has the nation's most aggressive anti-sprawl policies. Since 1990, Portland has experienced the largest increase in vehicle travel per square mile of any urban area over 1 million population. Roadway congestion in Portland is among the worst in the nation.
Thanks to Abhijeet Chavan