This bill establishes a transportation carbon budget for the state of Connecticut. The Commissioner of Transportation, in consultation with the Commissioner of Energy and Environmental Protection, will establish the maximum amount of greenhouse gas emissions permitted from the transportation sector. The commissioners will consider the long-term emission reductions required by current law when establishing the transportation carbon budget. The Commissioner of Transportation will also adopt regulations to ensure that transportation projects undertaken by the Department of Transportation, metropolitan planning organizations, and municipalities do not exceed the maximum amount of greenhouse gas emissions established in the transportation carbon budget. The regulations will include a definition of "transportation project" that excludes projects necessary for safety reasons or maintenance, a methodology to calculate greenhouse gas emissions from future transportation projects, ways to offset emissions from projects that increase net emissions, and a description of greenhouse gas mitigation transportation projects. The Commissioner of Transportation will implement a public outreach plan to engage the public and stakeholders in the development of the transportation carbon budget and regulations. The Commissioner will also submit reports to the General Assembly on the status of the development of the transportation carbon budget and regulations, the level of collaboration among stakeholders, and the results of public outreach efforts. The Commissioner will submit a copy of the transportation carbon budget and any legislative recommendations to the General Assembly annually. The bill takes effect on October 1, 2023.