Understanding Lifecycle GHG Impacts of Emissions Reduction Strategies

Focus Area

Climate Change


Air Quality






1-2 years

Research Idea Scope

An increasing number of DOTs and MPOs are considering greenhouse gas (GHG) emissions as part of the planning process, particularly in response to new federal programs addressing on-road GHG emissions. However, most readily-available GHG analysis tools and resources have limitations that may affect their ability to inform current transportation decisions. 1). Commonly-used emissions models and other quantification tools are limited to vehicle tailpipe GHG emissions. Accounting for complete lifecycle emissions from transportation infrastructure, fuels and vehicles can significantly change estimates of GHG emissions associated with project alternatives or different GHG reduction strategies. 2). Comprehensive studies of GHG reduction measure are often based on increasingly dated analysis that may no longer be relevant in light of in light of long-term changes in travel behavior (following the COVID-19 pandemic), evolution of the on-road vehicle fleet, and other social, technological and policy changes. 3). Emerging strategies such as EV adoption, EV infrastructure deployment and micromobility cannot be easily analyzed on a lifecycle using existing travel demand and emissions models, and there is also a limited body of published research to guide practitioners’ analysis of these measures.
The purpose of this study is to develop an up-to-date practitioners’ reference to that quantifies the lifecycle GHG emissions impacts and cost effectiveness of current mitigation strategies. A primary element of this study would be a comprehensive literature review that will be used to identify a list of strategies along with estimates of GHG reductions and implementation costs. The literature review would also address factors that could impact the relative effectiveness of strategies in different geographic and policy contexts. For a majority of these strategies, it is assumed that existing literature will not address full lifecycle impacts, and models such as the Infrastructure Carbon Estimator (ICE) and the Greenhouse Gases, Regulated Emissions and Energy Use in transportation (GREET) could be used to estimate the missing components. In limited instances, the research team could also develop simple estimation methods to address considerations that are not well represented in literature or by other off-the-shelf models.

Urgency and Payoff

The Intergovernmental Panel on Climate Change has warned that significant action in the next several years is critical to avoid potentially irreversible impacts of climate change. U.S. transportation sources directly account for 28 percent of U.S. GHG emissions –which is more than any other U.S. sector – and additional GHG emissions are produced indirectly from the construction and maintenance of transportation infrastructure, the production of transportation fuels, and the manufacture of vehicle further increases the transportation sector’s share of U.S. and global emissions. Lifecycle-based GHG estimates are critical to identifying the most effective reduction opportunities for programs such as the Carbon Reduction Program; they also help practitioners unintended consequences of promoting strategies that reduce tailpipe emissions but increase indirect emissions.

Suggested By

Natalie Liljenwall

[email protected]