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Planners in Portland use a transportation forecast

model that the U.S. Department of Transportation regards as

one of the most sophisticated in the nation.  In 1994 plan-

ners applied the model to a plan for increasing Portland's

density by 75 percent, emphasizing mixed-use and transit-

oriented developments, and building 120 miles of rail lines

but minimal new highway capacity.  The model concluded that

the plan would induce less than 5 percent of auto drivers to

shift to mass transit.  That in turn would increase conges-

tion more than threefold.43

In 1980 San Diego imposed a New Urbanist plan on its

region, encouraging density in the city and discouraging

development outside.  The plan "was considered a model for

effective management of growth."  But by 1990 congestion had

become severe, and the city "estimated that it would cost

over $1 billion to make up the infrastructure shortfall."44

The Issue of Air

Air pollution is obviously the result of many factors,

including geography, industry, energy sources, and climate.

But in major U.S. cities and metropolitan areas, smog prob-

lems are strongly correlated with population density.45

Table 2 shows the average 1990 population densities of

areas by EPA smog rating.  The table shows both the 391

metropolitan areas defined by the Census Bureau and the 76

central cities with more than 200,000 people.  In every

case, cleaner air correlates with lower densities.

It is worth examining the cities that come closest to

meeting the New Urbanists' ideal of higher densities; low

per capita freeway mileage; mixed-use developments; and huge

transit, especially rail transit, investments.  The major

metropolitan areas with the highest densities are Los Angel-

es, Miami, San Jose, New York, Ft. Lauderdale, New Orleans,

and San Diego.  Those cites also tend to be characterized by

mixed-use developments, and all have or are installing major

rail systems.  Except San Jose, which has "moderate" prob-

lems, all of those high-density cities are rated by the EPA

as having "extreme" or "serious" smog problems.

People are often surprised to learn that the Los Angel-

es metropolitan area has the greatest population density of

any U.S. urban area.46  Los Angeles also has the fewest

miles of freeways per capita--slightly more than 50 miles

per million people, compared to an average of 110 miles for