The Federal Highway Administration released the Handbook for Estimating Transportation Greenhouse Gases for Integration into the Planning Process in 2013.

This publication is a handbook designed to provide information on how to analyze on-road greenhouse gas emissions at the state and regional level, and how to incorporate those analyses into transportation planning efforts. The handbook is intended to help State DOTs and MPOs understand the possible approaches, data sources, and step-by-step procedures for analyzing GHG emissions. It provides an overview of estimating GHG emissions in the planning process, and identifies and describes several key methodologies used to estimate emissions. It also provides a discussion of the strengths and weaknesses of each methodology, and includes a section designed to help users identify which methodology is best for their situation.