Ask the Experts–Reducing Greenhouse Gas Emissions and Supporting Energy Independence at the State and Regional Levels

Government agencies at all levels are increasingly setting aggressive targets to reduce greenhouse gas (GHG) emissions and mitigate the potential impact of climate change. These targets can range up to an 80 percent reduction in emissions levels by the year 2050, compared to 1990 levels. Achieving such aggressive targets will not be possible without significant contributions from the transportation sector. And because reducing GHG emissions also means reducing our fossil fuel use – transportation action on climate change can support greater energy independence at the same time.

Just like mom and apple pie, right? Well it’s not that easy. At today’s fuel economy rates, to achieve a 1 million metric ton reduction of carbon emissions (about 2.5 percent of an average state’s transportation emissions), VMT would need to be reduced by approximately 2 billion.

To reduce GHG emissions and fossil fuel use from transportation in the long run, we’ll need to rely heavily on technology solutions – more fuel-efficient vehicles and decarbonized fuels. While these solutions generally fall outside a transportation agency’s direct jurisdiction, an agency can take supportive actions such as purchasing alternative-fuel and high-efficiency vehicles in its fleet, or investing in infrastructure – such as refueling or recharging stations – that make these new technologies more feasible.

Most analyses, however, show that technology improvements alone will not be sufficient to meet many of the aggressive targets already set for reducing GHG emissions. While analysts debate how much VMT reduction will be required, most agree that travel and the associated VMT need to be addressed to achieve real GHG emission reductions and support energy independence. These are areas in which transportation agencies do have substantial authority.

State DOTs’ Contributions

What can state DOTs and MPOs do? For starters they can…

  • Adopt policies describing how they will support state efforts to reduce GHG emissions, such as the Massachusetts DOT’s GreenDOT policy;
  • Examine State and regional plan alternatives and their potential impact on GHG emissions and energy use;
  • Build understanding of the transportation and land use connection and its long-term impacts on transportation energy requirements; and
  • Examine the relationships between energy and environmental sustainability and the fiscal and economic sustainability of the transportation system.

Transportation agencies can also take more specific actions through project and programming decisions. In 2009 we conducted a study for the National Cooperative Highway Research Program (NCHRP) examining state DOTs’ contributions to reducing GHG emissions. While it was difficult to precisely quantify these contributions, we estimated that actions by DOTs taken over the past decade have contributed to reductions of up to 300 million metric tons carbon dioxide equivalent (CO2e), or 1.5 percent of on-road emissions. We concluded that by expanding these actions in the future, CO2e emissions could be reduced by up to 1,100 million metric tons over the 2010-2030 time frame, or nearly 3.5 percent of on-road emissions. The actions that we examined included:

  • Investing in alternative modes of travel, including transit and nonmotorized infrastructure;
  • Supporting travel demand management programs to give people information about and incentives for travel alternatives, especially for commuting;
  • Timing traffic signals more efficiently, and implementing intelligent transportation system (ITS) solutions such as incident management and integrated corridor management to improve traffic flow;
  • Implementing idle reduction programs to reduce extended idling by trucks; and
  • Making changes to agency construction, maintenance, and operations practices, such as substituting fly ash for cement, using warm-mix instead of hot-mix asphalt, and requiring construction contractors to implement fuel-saving practices.

The total reductions achievable through these actions may seem modest in comparison to overall targets, but these contributions are important when combined with efficiency improvements and reductions in other sectors. Furthermore, most of these actions come with a variety of other benefits, such as improved mobility, safety, air quality, and community livability.

Supporting Other State and Local Actions

Local actions to reduce the need for travel are more effective when supported by state DOT and MPO policies and practices. Over the long term, recent studies including Moving Cooler, Growing Cooler, and a Transportation Research Board report have estimated that changes to land use patterns can reduce total transportation GHG emissions by up to 10 percent by 2050, or urban light-duty VMT by up to 18 percent. Transportation agencies play an important role in shaping these patterns through their choice of transportation investments. Funding can be redirected to support infrastructure in existing communities, infill, and targeted “smart growth” areas rather than exurban greenfields sites. Context-sensitive solutions and “complete streets” policies are essential to supporting walkable communities and improving travel choices. Investments in rail infrastructure can support more efficient ways of moving both people and goods.

Two other GHG reduction strategies that have strong potential with few downsides include “pay-as-you-drive” insurance and “eco-driving.” Pay-as-you-drive (PAYD) insurance changes today’s fixed-cost automobile insurance programs to a system where consumers pay a portion of their insurance based on how far they drive. PAYD programs, which have been piloted in at least five states, not only provide an incentive to reduce travel but also save the majority of consumers money. Generally, state legislation is needed to allow or more strongly encourage insurers to charge by the mile. If implemented on a widespread basis, PAYD could reduce light-duty VMT and emissions by around four percent or more. Similarly, teaching drivers how to drive and maintain their vehicles more efficiently (“eco-driving”) could reduce fuel use from both cars and trucks by around five percent. A pilot eco-driving program is underway in the San Francisco Bay Area and some commercial fleet operators, such as UPS and Staples, have already taken steps to integrate eco-driving practices into their driver training and equipment.

State DOTs and MPOs can play a role in these strategies by implementing pilot programs, or by working with other state agencies and industry groups. As transportation professionals, we have unique expertise that we can contribute to these broader climate change and energy reduction efforts.

Cambridge Systematics, Inc. is a national leader in climate change and GHG planning and analysis, supporting Federal, state, and regional agencies. We supported the U.S. DOT’s Report to Congress on Transportation’s Role in Reducing U.S. Greenhouse Gas Emissions, the most comprehensive analysis of transportation strategies produced to date, released on Earth Day 2010.

For Further Reading

Cambridge Systematics, Inc. (2009). Transportation Program Responses to GHG Reduction Initiatives and Energy Reduction Programs. Prepared for NCHRP Project 25-25, Task 45.

Cambridge Systematics, Inc. (2009). Moving Cooler: An Analysis of Transportation Strategies for Reducing Greenhouse Gas Emissions. Urban Land Institute, Washington, D.C.

Ewing, R., et al. (2008). Growing Cooler: The Evidence on Urban Development and Climate Change. Urban Land Institute, Washington, D.C.

Massachusetts Department of Transportation (2010). GreenDOT Policy Directive. Policy P-10-002.

Transportation Research Board (2009). Driving and the Built Environment. Special Report 298.

U.S. Department of Transportation (2010). Transportation’s Role in Reducing U.S. Greenhouse Gas Emissions. Report to Congress.