8.1 Environmental impacts of transportation

Transportation is a major contributor to environmental issues, accounting for about 14% of global greenhouse gas emissions. From air and noise pollution to habitat fragmentation, its impacts are far-reaching and complex.

Measuring these impacts involves carbon footprints, life cycle assessments, and evaluating effects on air quality, biodiversity, and infrastructure. Mitigation strategies range from emission control technologies to sustainable urban planning and wildlife conservation efforts.

Transportation's Carbon Footprint

Measuring and Quantifying Emissions

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• Carbon footprint measures total greenhouse gas emissions caused by individuals, organizations, events, or products
  • Expressed as carbon dioxide equivalent (CO2e)
• Transportation contributes ~14% of total annual global greenhouse gas emissions
• Carbon intensity varies by transportation mode
  • Aviation and personal vehicles generally have higher emissions per passenger-mile
  • Public transit options tend to have lower emissions per passenger-mile
• Electric vehicle carbon footprint depends on carbon intensity of electricity grid used for charging
• Factors affecting transportation emissions
  • Vehicle efficiency
  • Occupancy rates
  • Fuel type
  • Operational practices

Evaluating Environmental Impact

• Life cycle assessment (LCA) evaluates total environmental impact of transportation modes
  • Covers production to disposal phases
• Emerging low-emission technologies under development
  • Hydrogen fuel cells
  • Sustainable aviation fuels (SAF)

Transportation's Environmental Impacts

Air Quality Effects

• Transportation releases significant air pollutants
  • Particulate matter (PM)
  • Nitrogen oxides (NOx)
  • Volatile organic compounds (VOCs)
• Vehicle emissions contribute to ground-level ozone formation
  • Major component of smog
  • Causes respiratory issues and environmental damage
• Traffic-related air pollution (TRAP) linked to health problems
  • Cardiovascular diseases
  • Respiratory diseases

Noise and Heat Pollution

• Transportation noise pollution in urban areas leads to health issues
  • Stress
  • Sleep disturbance
• Urban heat island effect exacerbated by transportation infrastructure
  • Asphalt roads and parking lots absorb and retain heat

Mitigation Strategies

• Emission control technologies reduce pollutants
• Urban planning aims to decrease traffic
• Promotion of active transportation modes (walking, cycling)
• Low emission zones in cities improve air quality
• Congestion pricing reduces traffic and associated pollution

Environmental Costs of Transportation Infrastructure

Lifecycle Impacts

• Transportation infrastructure lifecycle includes multiple phases
  • Raw material extraction
  • Manufacturing
  • Construction
  • Operation
  • Maintenance
  • Demolition or repurposing
• Construction causes significant environmental impacts
  • Habitat destruction
  • Resource depletion
  • Emissions from heavy machinery and material production
• Road construction materials have large carbon footprints
  • Concrete production energy-intensive
  • Asphalt production energy-intensive
• Ongoing maintenance activities contribute to environmental impacts
  • Road resurfacing
  • Bridge repairs

Assessment and Mitigation

• Life Cycle Cost Analysis (LCCA) evaluates full economic costs of infrastructure projects
• Environmental Impact Assessment (EIA) evaluates full environmental costs of infrastructure projects
• Material and construction method choices affect long-term environmental performance
• Sustainable infrastructure design principles reduce lifecycle environmental costs
  • Use of recycled materials
  • Green stormwater management techniques

Transportation and Biodiversity Loss

Habitat Fragmentation

• Transportation infrastructure creates barriers disrupting wildlife
  • Roads and railways fragment habitats
  • Disrupt animal movement patterns
• Fragmentation leads to ecological consequences
  • Reduced genetic diversity within species populations
  • Increased vulnerability to local extinctions
  • Altered ecosystem functions
• Edge effects from transportation corridors impact ecosystems
  • Alter microclimate conditions
  • Facilitate spread of invasive species

Direct Wildlife Impacts

• Road mortality threatens many animal species
  • Particularly affects species with large home ranges
  • Impacts migratory species
• Transportation noise pollution disrupts animal behavior
  • Affects communication between animals
  • Disturbs reproductive patterns
• Light pollution from transportation impacts wildlife
  • Alters natural day-night cycles for animals

Conservation Strategies

• Wildlife crossings reduce habitat fragmentation impacts
  • Eco-bridges allow animals to safely cross roads
  • Culverts provide passage for smaller animals
• Transportation network planning can incorporate biodiversity conservation principles
  • Minimize negative impacts on ecosystems
  • Preserve critical habitats and migration corridors