California Department of Transportation

Environmental Considerations

Freight Planning Fact Sheets

Trucks, freight trains, container ships, cargo planes, and freight-handling equipment are associated with environmental effects, both in terms of operation as well as the construction of related infrastructure improvements.  Particularly significant effects are associated with air quality issues related to diesel emissions. Freight movement affects the surrounding communities and contributes to greenhouse gas emissions (GHG) that contribute to climate change.  These and other impact areas are addressed under federal and state environmental laws and regulations, many of which provide processes that help avoid or reduce adverse effects. 

The Caltrans Headquarters Air Quality Branches manage the Department’s air quality analysis and transportation conformity policy; assist the district offices with regional and project-level air quality issues; consult and coordinate with state, federal, and regional air and transportation planning agencies; build and maintain air quality analysis tools and procedures; and manage research studies related to transportation air quality issues.

Community Impacts

While goods movement industries support many jobs and transport food and other products we need, communities near major highways, seaports, rail yards, border crossings, freight distribution centers, intermodal transfer facilities, and other “gateways” and “hubs” of domestic and international trade may be adversely affected in terms of air pollution, noise, congestion, health, and quality of life.  Often, the effects of transportation projects are borne by the communities residing near the freight corridor, while the benefits of goods movement are shared by a larger population at the regional, state, or national level.

Air Quality and Diesel Emissions

Goods movement has traditionally been powered by diesel engines in locomotives, marine vessels, and heavy-duty trucks, which produce tons of emissions in the form of particulate matter (PM), nitrogen oxides (NOx), and sulfur oxides (SOx).  Diesel engines emit a complex mix of pollutants, including very small carbon particles (“soot”) called diesel PM, known to contain over 40 cancer-causing substances.  Air pollution accumulates from multiple sources around ports, rail yards, and other multimodal facilities. 

Both the U.S. Environmental Protection Agency (EPA) and California Air Resources Board (ARB) classify diesel PM as a toxic air contaminant based on its potential to cause cancer, premature death, respiratory and cardiovascular effects, and other health problems.  ARB is the State agency charged with developing statewide programs and strategies to reduce the emission of smog-forming pollutants and toxics by diesel-fueled mobile sources.  ARB also actively promotes and disperses grant and incentive programs to assist trucking and freight operators comply with clean air regulations.  

Climate Change

The California Global Warming Solutions Act of 2006 (also known as Assembly Bill 32) requires that California reduce its GHG emissions to 1990 levels by 2020.  The California Air Resources Board (ARB) estimates that passenger vehicles account for most of approximately 38% of the State’s GHG emissions; however, goods movement-related transportation is also a significant contributor.  Of all transportation sources on a national scale, heavy-duty vehicles generate 19% of greenhouse gas emissions.  Information on measures to address GHG emissions can be found in ARB’s AB 32 Climate Change Scoping Plan.  The State’s adaptation strategy can be found at the California Climate Change Portal. Information regarding Caltrans climate change projects and studies is available on the Caltrans Climate Change Branch webpage.

Environmental Review

Publicly sponsored, funded, or approved projects that may potentially affect the environment must comply with a number of federal, state, and local environmental laws and regulations.  The primary federal and State environmental mandates are the federal National Environmental Policy Act (NEPA) and the California Environmental Quality Act (CEQA), respectively.  

Under NEPA and CEQA, a wide variety of potential impact areas are assessed related to the physical and natural environment, land use, cultural resources, socioeconomic effects, climate change, cumulative effects, and other topics.  Other important mandates governing freight planning include the federal and State clean air acts and environmental justice requirements.  For detailed guidance on Caltrans’s compliance with these and other environmental laws, see the Standard Environmental Reference (SER), maintained by the Division of Environmental Analysis.

Environmental Regulation of Trucks

Environmental Regulation of Trucks

The California Air Resources Board (ARB) is responsible for developing statewide programs and strategies to reduce the emission of smog-forming pollutants and toxics by diesel-fueled mobile sources.  Several of their programs and strategies are related to heavy-duty trucks.  The ARB also offers financial assistance for retrofitting, repowering, or replacing trucks to reduce emissions. 

Additional information can be found at the following ARB web pages:

  • The Truck Stop web page has information on clean air requirements for diesel vehicles, trailers, transport refrigeration units (TRUs), and on funding.  ARB’s diesel hotline is (866) 634-3735 or (866) 6-DIESEL.
  • On-Road Diesel Activities web page includes information on the Heavy-Duty In-Use Vehicle Regulation and the Port Trucks / Drayage Trucks Regulation, and related links on financial assistance programs.
  • Drayage trucks web page outlines the compliance options for owners of drayage trucks to upgrade or replace truck engines in accordance with current regulations. 
  • ARB’s required registration for drayage trucks is also available online at this link. All trucks must be registered prior to port or rail yard entry.  A fact sheet on ARB’s Drayage Truck Registry is available here.
  • Requirements for Diesel Truck and Equipment Owners Fact Sheet (includes information about grants to help fleets and individuals comply with California regulations).  
  • Heavy-Duty Vehicle Air Quality Loan Program Fact Sheet provides information about a State loan program to provide financial assistance to truckers affected by the Statewide In-Use Bus and Truck Rule and the Heavy-Duty Vehicle Greenhouse Gas Emission Reduction Measure.
  • Funding Fact Sheet for Retrofits and Upgrades also provides information about incentive funding (over $1 billion) available for on-road heavy-duty diesel vehicle replacements and retrofits.

Also see the Office of System and Freight Planning’s Environmental Considerations web page for additional information.

Goods Movement Environmental Resources

Listed below are web resources and documents related to goods movement, air quality and climate change, including a list of funding resources to help implement emission reduction strategies.

California Goods Movement and the Environment

Emission Reduction Funding Resources



California Ports and the Environment

Railroads and the Environment



Federal Resources