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Cities are an environmental abomination. . . Right?. “ The growth of cities will be the single largest influence on development in the 21st century. ” UN, 1996, State of World Population. Largest urban areas. - PowerPoint PPT Presentation
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Cities are an environmental abomination. . .
Right?
• “The growth of cities will be the single largest influence on development in the 21st century.” – UN, 1996, State of World Population
Largest urban areas• 1. Tokyo, Japan - 28,025,000
2. Mexico City, Mexico - 18,131,000 3. Mumbai, India - 18,042,000 4. Sáo Paulo, Brazil - 17, 711,000 5. New York City, USA - 16,626,000 6. Shanghai, China - 14,173,000 7. Lagos, Nigeria - 13,488,000 8. Los Angeles, USA - 13,129,000 9. Calcutta, India - 12,900,000 10. Buenos Aires, Argentina - 12,431,000
•
•
•
What’s bad about cities?
•
Air quality
• Magnitogorosk, RU
• Hyderabad, IND
Air quality
• Primary and secondary air pollution• Primary: directly emitted
– Particulate matter: pm10 and pm5– Lead
• Secondary: forms in atmosphere– Ground level ozone
Impermeable surfaces
Impermeable surfaces
• Don’t allow water to sink into the ground• Instead, water runs off quickly to storm
drains– Overwhelms sewage treatment plants, OR– Goes directly to nearby water bodies
Cities influence climate
• Urban heat island effect• Roads, buildings, other infrastructure
replace vegetation• Absorb solar energy during day, radiate heat
at night– Roofs, roads can be 50-90 deg. F hotter than
air temperature!
•
Major Urban Problems in U.S.• Deteriorating services• Aging infrastructures• Budget crunches from lost tax revenues as
businesses and affluent people leave • Rising poverty with violence, drugs, decay• Urban sprawl - growth of low-density
development on edges of cities and towns– 9 consequences of “bad growth”
75% of the US population live in urban areas occupying 3% of the country’s land area
Urban Resource and Environmental Problems
• Destruction of plant life - what is $ value?• Cities produce little of own food• Urban heat island effect • Water supply and flooding problems• High pollution exposure
Urban Resource & Environmental Problems
• Excessive noise exposure health effects– Hearing loss, hypertension, muscle tension,
migraines, headaches, higher cholesterol levels, gastric ulcers, irritability, insomnia, psychological disorders, aggression
Urban Resource & Environmental Problems• Beneficial effects:
– education– social services– medical care
• Harmful effects – infectious disease spread
• high density population• inadequate drinking and sewage system
– physical injuries – pollution exposure– Urban Sprawl
What’s good about cities?
•
Transportation
• Greater use of mass transit and less use of private automobiles
• Much more walking in some cities
transportation
• Energy efficiency of different forms– Btus per person mile– Vanpool 1322– Eff. Hybrid 1659– Commuter rail 2996– Cars 3512– Air 3261
Fighting obesity
• City dwellers less likely to be obese– St. John Newfoundland 36%– Toronto 16%– Vancouver 12%– New York City 20%
City
Energy consumption- quad. BTU
4. 02
Per householdMillion BTU
85.3
Per household memberMillion BTU
33.7
town 1.94 102.3 39.7
suburb 2.46 108.6 40.3
rural 2.13 95.1 37.8
•
Alternatives to cities
• Suburbs– Developed during 20th century– People wanted space
• Loans, returning veterans– Transportation: cars made living in one
place, working in another possible• Westchester cty, NY: world’s first large-
scale suburban development
•
•
Sprawl development
• Spreading outward of city and suburbs• Low-density development
– Single family homes, large lots– Auto dependent development
• Long distances to work
• Calgary, Alberta
Strip malls
•
•
Zoning
• Laws that regulate land use in a city or town are zoning laws (or regulations).
Smart Growth
• A new development paradigm– Restoring center cities or older suburbs– Transit and pedestrian oriented– Mix of housing, retail, entertainment, other uses
•
Urban considerations
• Energy use• Transportation• Cars vs. bikes vs pedestrian vs mass transit• Living space• Recycling• Lack of green space
• The American Dream
Urban Sprawl
Urban Sprawl: Causes & Effects
• (1) Automobiles and Highway Construction
• (2) Living Costs• (3) Urban Blight• (4) Government Policies
(1) Automobiles and Highway Construction
• 1950’s: the Interstate Highway System
• Commuting
• Work in the city and live in the suburbs
• Best of both worlds!
(2) Living Costs
• The American Dream• More Land• Larger House• Privacy• Lower taxes• Overall, higher standard of living Levittown
• Excludes low income families
(3) Urban Blight
• The degradation of the built and social environments of the city that often accompanies the accelerated migration to the suburbs
• A positive feedback loop
(3) Urban Blight
• People leaving cities• Shrinking tax revenues• City still must provide: police, fire, trash, sewage,
public transportation, and social services
• Cities reduce services• Crime increases• Infrastructure deteriorates• Built environment declines
(3) Urban Blight
• Suburban office parks• Suburb to suburb commuting• Can’t provide public transportation b/c too
spread out
• Commute around cities instead of through them
• No need to go to the stores in a city
(3) Urban Blight
• Contributed to Racial Segregation• “White Flight”
• Generated a disparity of opportunity• Suburban Property tax revenues allow for
better schools
• Example: Busing in Boston 1974
(4) Government Policies
• Highway Trust Fund– Highway Revenue Act 1956
• Federal gasoline tax to fund road construction/maintenance
– Induced Demand
• Who can Explain this Positive Feedback mechanism?
(4) Government Policies
• Zoning• Restrict land use to specific areas: residential,
industrial, commercial
• In the suburbs, where the traditional “Main Street?”
• new tool: multi-use zoning
(4) Government Policies
• FHA (1930’s)• Federally Subsidized Mortgages• Only wrote them in the financially low-risk
areas
Levittown (before)
Levittown (after)
Smart Growth
• Development of sustainable, healthy communities
Mixed Land Use Create walkable Neighborhoods
Create a Range of Housing Opportunities Encourage community and stakeholder collaboration in development decisions
Take advantage of compact building design
Foster distinctive, attractive communities with a strong sense of place
Provide variety of Transportation Choices Preserve open space, farmland, natural beauty, and critical environmental areas
Strengthen, direct development toward existing communities
Make development decistions predictable, fair, and cost-effective
Smart Growth
• Transit Oriented development• Portland, OR
• Infill• Urban Growth Boundaries
Foster distinctive, attractive communities with a strong sense of place
Concentric Circle Model
1. Central business district (CBD)2. Deteriorating transition zone3. Worker’s homes4. Middle-class suburbs5. Commuter's zone
Sector Model
1. High-rent residential2. Intermediate-rent residential3. Low-rent residential4. Education and recreation5. Transportation6. Industrial7. Core (CBD)
Multiple-Nuclei Model1. CBD2. Wholesale, light manufacturing3. Low-rent residential4. Intermediate-rent residential5. High-rent residential6. Heavy manufacturing7. Outlying business district8. Residential Suburb9. Industrial Suburb
Impacts of Urban Sprawl
Land and Biodiversity
Loss of cropland
Loss of forests & grasslands
Loss of wetlands
Loss & fragmentation ofwildlife habitats
Increased wildlife road kill
Increased soil erosion
Human Healthand Aesthetics
Contaminated drinking water & air
Noise pollution
Sky illumination at night
Traffic congestion
Water
Increased runoff
Increased surface water & groundwater pollution
Increased use of surface water & groundwater
Decreased storage ofSurface water &
groundwater
Increased flooding
Decreased naturalSewage treatment
Impacts of Urban Sprawl
Energy, Air, and Climate
Increased energy useand waste
Increased air pollution
Increased greenhouse gas Emissions
Enhanced global warming
Warmer microclimate(heat island effect)
Economic Effects
Higher taxes
Decline of downtownbusiness districts
Increased unemploymentin central city
Loss of tax base in central city
Transportation and Urban Development
• Determines where people live, where they go to work and buy stuff, how much land is paved and exposure to air pollution
• Cities grow up if they can’t grow out; more prone to use mass transit
• Urban sprawl due to cheap gas and land and highways; dispersed car-centered cities use 10x more energy
Drive alone 80%
Other 4%
Public transit 5%
Car pool 11%
Motor vehicle concentration• Ground transportation: individual (cars, etc) and mass
(buses and rail)• U.S. has 35% of cars and trucks used for 98% of all
urban transportation• Motor scooters - effort to change to electric• Riding bicycles; less pollution and dangerous and more efficient than walking
– bicycles available for public use– bike and ride systems
Pros and Cons of Mass transit
• 3% mass transit use in U.S. to 47% in Japan• 20% gasoline tax revenues to mass transit• Rapid rail, suburban trains and trolley - efficient
at high population density• High speed rail lines – replace planes, buses and
private cars; but require large government subsidies
• Bus systems more flexible than rail systems but efficient when full