Description

Despite California’s ambitious target to achieve carbon neutrality by 2045, the state is not reducing greenhouse gas (GHG) emissions from personal vehicle travel, and per capita Vehicle Miles Traveled (VMT) and GHG emissions continue to increase. One central challenge of climate planning facing California is the lack of consistent methods to measure the VMT impacts of transportation projects. Using both qualitative and quantitative data, this research answers the question: “What are the advantages and limitations of existing VMT calculators to determine the climate impacts of transportation projects to help meet California’s climate goals?” Research methods included: (1) a quantitative analysis of the existing VMT tools in practice, particularly in California, by identifying and analyzing the attributes of each tool and clustering the tools into distinct methods based on their similarities in principles, inputs, and outputs; and (2) a qualitative analysis of perspectives of transportation professionals regarding VMT as a metric and VMT tools. Findings indicate that the consistency, contextual relevance, complexity, data accuracy, and the user-friendliness of the VMT tools vary significantly based on their design and methodology, and each tool presents a set of limitations and advantages making it suitable for a specific use or context but not necessarily for another. Recommendations for the state include to: (1) improve access to accurate, validated data for creating and inputting into VMT models and tools; (2) help create context sensitive VMT tools capable of capturing local context and change over time;(3) strengthen dialogue between jurisdictions to share information and tools; and (4) encourage the use of an integrated approach to VMT analysis—which often combines use of different tools and datasets for various stages of decision-making and scenario planning. VMT tools help planners and policymakers estimate VMT and understand the impacts of transportation projects and policies. By improving our understanding of these tools and their advantages and disadvantages, we can choose the best tool for the specific need, ensuring accurate VMT assessments and empowering California to further its climate goals.

Publication Date

12-2024

Publication Type

Report

Topic

Planning and Policy, Transportation Technology

Digital Object Identifier

10.31979/mti.2024.2314

MTI Project

2314

Keywords

Vehicle miles traveled (VMT), Induced demand, Greenhouse Gas (GHG) Emissions, Transportation impact analysis

Disciplines

Environmental Policy | Policy Design, Analysis, and Evaluation | Transportation | Urban Studies

Additional Files
2314-RB-Alexander-VMT-GHG-Transportation-Impact-Analysis.pdf (306 kB)
Research Brief
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