The Department of Transportation on Thursday proposed a new requirement that states and metropolitan areas measure the amount of carbon dioxide being released through driving on interstate highways and other major roads.

The proposed rule would obligate state and local officials to set targets to reduce emissions in the coming years, using 2021 as the baseline. It would add emissions to an existing list of performance measures – originating from transportation bills in 2012 and 2015 – that includes data on safety, congestion, pavement and other items.

Transportation Secretary Pete Buttigieg Matt Rourke, File/Associated Press

Transportation is the top U.S. source of greenhouse gas emissions, and federal highway officials under President Joe Biden say the proposed regulation is meant to bring clearer data, increased transparency and better decisions at all levels of government and among the driving public. The rule is intended to track and reduce tailpipe emissions that spur climate change.

The Biden administration effort is similar to a greenhouse gas measurement enacted in the final days of the Obama administration. The Trump administration, saying that the earlier plan imposed “unnecessary regulatory burdens . . . with no predictable benefits,” repealed the requirement in 2018 before states had to take action.

“Climate change results from the incremental addition of [greenhouse gas] emissions from millions of individual sources, which collectively have a large impact on a global scale,” according to the proposal. It states that better information can increase public awareness about emissions trends and illuminate the “trade-offs among competing policy choices” of different types of transportation projects.

“We don’t have a moment to waste,” Transportation Secretary Pete Buttigieg said in a statement. “Our approach gives states the flexibility they need to set their own emission reduction targets while providing them with resources from President Biden’s Bipartisan Infrastructure Law to meet those targets and protect their communities.”

Failing to hit the emissions targets would have little legal consequence. If significant progress is not made, the state transportation department “shall document the actions it will take to achieve the target,” according to the proposal.

The effort brought pushback from some Republicans and the road-building industry. Sen. Shelley Moore Capito, R-W.Va., ranking member of the Committee on Environment and Public Works, said the greenhouse gas performance measure represents an overreach that was not part of last year’s infrastructure bill.

“Unfortunately, this action follows a common theme by both DOT and the administration, which is implementing partisan policy priorities they wish had been included in the bipartisan bill that the president signed into law,” she said in a statement.

Nick Goldstein, vice president of regulatory and legal issues at the American Road & Transportation Builders Association, said a Supreme Court decision late last month that restricts the Environmental Protection Agency’s ability to regulate carbon from power plants underscores a similar problem in the Department of Transportation’s approach to greenhouse gases. He said his members don’t believe Congress intended for the Federal Highway Administration to regulate greenhouse gases.

“The larger point was agencies need to comply with the authority and the mission that was explicitly given to them by Congress,” Goldstein said. “The same logic applies here. The Department of Transportation is going outside its lane in this rule and trying to act like the EPA.”

The Federal Highway Administration argued that Congress listed “environmental sustainability” as part of key “national goals and performance management measures” under federal law.

“The environmental sustainability, and specifically the carbon footprint, of the transportation system is a critically important attribute that State DOTs can and should use to assess the performance of the Interstate and non-Interstate National Highway System (NHS),” according to the proposal.

In addition to interstates, the National Highway System — which is what’s covered under the proposed rule — includes roads that are important to the nation’s economy, defense and mobility, according to federal highway officials.

Sen. Thomas R. Carper, D-Del., chairman of the Environment and Public Works Committee, said Transportation Department officials are following congressional intent.

“Congress created a national goal of making our roads, highways and bridges environmentally sustainable a decade ago,” he said in a statement, noting that Congress directed the Transportation Department “to establish a system for states to measure their performance toward that goal — an authority the department has rightly used” in the proposal released Thursday.

Under the proposal, state and local officials would use data on fuel consumption and driving distances to tally on-road carbon dioxide emissions. They would then calculate the percentage of driving that takes place on the National Highway System, and that total would be the basis for the required “declining targets” on carbon emissions.

States would set statewide emissions reduction targets two and four years into the future, according to the proposal, which notes the administration has set a goal of cutting emissions by half of 2005 levels by 2030, and of reaching net-zero emissions by 2050.

For example, state departments of transportation “might set targets that would result in steady, incremental progress toward net-zero emissions, or that achieve aggressive early . . . reductions, or be more gradual at first and become more aggressive later,” according to the proposal.

States would submit their tally of total on-road emissions and the emissions from the National Highway System, but only the latter would be used to gauge performance, according to the proposal.