Judge rules against environmentalists in lawsuit over Caltrans’ I-80 project
A judge denied a petition from environmentalist groups to halt Caltrans’ highway expansion project on Interstate 80 in Yolo County while acknowledging that “widening freeways is almost never the best way to solve traffic congestion over the long term.”
The Natural Resources Defense Council, the Center for Biological Diversity and the Planning and Conservation League, as well as the Sierra Club and the Environmental Council of Sacramento, had filed petitions asking the court to intervene against Caltrans in May 2024. The groups argued that the transportation agency had violated the California Environmental Quality Act — better known as CEQA — in multiple ways. Among other things, they said that Caltrans had understated the negative effects of increasing vehicle mileage on I-80, and that Caltrans had not considered enough alternatives to its highway-widening plan in the environmental review process.
Alameda Superior Court Judge Michael M. Markman filed an order on Aug. 13 saying that although adding lanes to highways usually fails in the long-term, Caltrans had fulfilled its obligations under CEQA.
“Adding lanes helps alleviate congestion in the short term,” he wrote. “The problem is that the relief from congestion is only temporary. ... It is often only a matter of time before people begin to drive more.” He added that people start driving more because of the temporary congestion relief, a phenomenon referred to as induced demand.
The Sacramento Bee reached out to representatives for Caltrans and the Center for Biological Diversity, as well as attorneys for the Natural Resources Defense Council. A representative for the Center for Biological Diversity said attorneys from that organization and from the NRDC were still reviewing the decision. Caltrans declined to comment because the litigation is ongoing.
For the total $465 million project, Caltrans District 3 is constructing one lane in each direction on I-80 for about 8½ miles between Davis and Sacramento, as well as a short portion of the Capital City Freeway, signed as Highway 50, by the I-80 interchange. The new lanes will be “managed lanes” dedicated for both toll-payers and high-occupancy vehicles. The intention is to relieve traffic congestion.
Adding lanes to a freeway temporarily relieves congestion, but research has repeatedly shown that it ultimately leads to more traffic. The judge in the writ of mandate case acknowledged this, as has Caltrans’ parent agency, CalSTA. CalSTA said in 2021 that “highway capacity expansion has not resulted in long-term congestion relief and in some cases has worsened congestion, particularly in urbanized regions. ... As a result, we cannot continue the same pattern of highway expansion investment in California and expect different results.”
CalSTA encouraged agencies to consider alternative strategies, but that guidance has not been fully implemented at Caltrans. One alternative strategy was successfully deployed in New York City this year — “congestion pricing,” a specialized toll that has decreased traffic, cut air pollution and increased driver speeds by 15% in Manhattan since it went into effect in January.
What environmentalists argued in I-80 project case
In the I-80 widening case, one of the environmentalists’ arguments was that Caltrans had not considered enough alternatives to adding the HOV/toll lane. The petitioners argued that the agency should have, at a minimum, considered adding a toll lane as well as converting an existing lane to a toll lane. The California Air Resources Board had suggested studying that option. The board also suggested tolling all lanes. The judge rejected this.
Environmentalists said that Caltrans underestimated the negative affects of widening the highway because it used a flawed model for one part of its analysis while using a more accurate model from UC Davis for another part. The agency used estimates from UC Davis’ National Center for Sustainable Transportation vehicle miles traveled calculator for its induced travel demand mitigation plan and for an induced vehicle miles traveled impact analysis. The more accurate UC Davis model found that the project would lead to 100 million additional vehicle miles traveled per year. Caltrans’ internal model was used for its greenhouse gas emissions estimates.
In their petition, the Sierra Club and the Environmental Council of Sacramento said that Caltrans had engaged in “piecemealing” — separating environmental review processes of ostensibly discrete projects that were, the groups argued, actually just stages of the same ultimate project. Piecemealing has previously been found to obscure the total environmental impact of a project. The judge ultimately said that, in this case, he did not believe Caltrans had engaged in piecemealing under CEQA.
The Yolo 80 Corridor Improvement Project has been under added scrutiny since May 2024, when Caltrans won a California Transportation Commission grant outside the normal competitive grant process, essentially winning an “advance.” When Caltrans had previously competed against other agencies in the standard Trade Corridor Enhancement Program application cycle, it lost the grant.
Had the California Transportation Commission decided against awarding $105 million to the Caltrans District 3 Interstate 80 widening project, the entire funding strategy may have fallen apart.
Last summer, The Sacramento Bee examined the 2022 and 2024 grant applications submitted to the California Transportation Commission. Although the project itself had not changed, the way Caltrans officials described it changed in three key ways.
When it applied in 2022 and competed against other agencies, Caltrans said the project was its last priority: “Priority 24 of 24.” When it applied in 2024 and was not competing against other agencies, Caltrans said the project was “a top priority.” In 2022, the grant application said that Caltrans had acquired funding for an ostensibly separate pavement rehabilitation project in order to “assist the development” of the widening project. That was omitted from the 2024 application.
The 2024 application also had a greater sense of urgency than the competitive application from 2022. Last year, the agency warned that if the California Transportation Commission did not award the $105 million, then Caltrans would likely forfeit the $85.9 million it had won from the federal government. That federal money would have expired Sept. 30, 2024.
This story was originally published August 19, 2025 at 8:16 AM.
CORRECTION: This story has been updated to reflect the name of one of the lawsuit’s petitioners.
