In summary California transportation officials warn the fight over passenger vehicle standards might affect air quality, construction jobs, the economy — and ensure Californians stay stuck in traffic.

Unrelenting commutes. Lost construction jobs. A statewide economic shudder. Prepare for all three if California loses its clean air battle with the Trump administration.

That’s the warning from state transportation planning agency officials, who say the ongoing fight over passenger vehicle standards might cause collateral damage to road and public transit projects. That could affect air quality, construction jobs, the economy and, as projects designed to improve flow are delayed, ensure Californians stay stuck in traffic.

The clash is over proposed federal rollbacks to Obama-era fuel economy and greenhouse gas standards for vehicles. Trump’s Environmental Protection Agency also has proposed revoking a waiver that lets California make its own, stricter tailpipe emissions rules. The final rule hasn’t been released yet—and when it is, California intends to fight it in court.

“We will not yield on our standards.”

“Where we’re going to start is litigating,” California Air Resources Board chair Mary Nichols told CALmatters. “And we will not yield on our standards. So we will be enforcing our standards while that goes on.”

Still, she said, there’s no guarantee that California will win. In the meantime, the state must conform to air quality goals set by the EPA’s Clean Air Act. Falling short of those goals, Nichols said, could lead to lawsuits from groups that oppose freeway projects.

“Or, the Trump administration, which is showing in many ways these days a desire to hurt California, could decide that they would no longer fund highway programs that have previously been approved,” she said. “And then we would be unable to continue working on a bunch of different projects that are designed to improve traffic flow—because we wouldn’t have the federal funds.”

That’s where things get dicey for transportation infrastructure. About 93 percent of Californians live in parts of the state that aren’t meeting federal standards for pollutants like ozone or tiny airborne particles, according to a recent air board presentation. Transportation planners in these regions must show that road and transit projects won’t make the air worse.

Since California has historically bad air quality and, for now, the EPA’s permission to make its own strict clean car rules, the air board has a custom-built model to estimate emissions. Baked into that model is the assumption that cars are going to get cleaner over time.

“The ramifications are pretty dire.”

If the Trump administration yanks California’s waiver, that assumption breaks down and the model stops working. Instead, major transportation projects could run the risk of grinding to a halt while the state develops a new model for the EPA to approve. “It puts a big monkey wrench into how we deliver transportation projects,” said Chris Schmidt, Southern California planning and modal programs manager with the California Department of Transportation.

If the delays last long enough, federal dollars for some of those projects could disappear altogether thanks to use-it or lose-it provisions in the funding, according to Tanisha Taylor, director of sustainability for the California Association of Councils of Governments, a non-profit representing major transportation planning agencies.

There are a lot of “ifs” here, but in a worst-case scenario, the association calculates that roughly 2,000 projects totalling $130 billion could be affected. “The ramifications are pretty dire,” Schmidt said. “You’re talking about many, many projects, and we’re talking about lots and lots of money.”

That includes projects in the San Joaquin Valley, which suffers from major air quality problems. Andrew Chesley, executive director for the San Joaquin Council of Governments, points to a safety improvement project slated for fiscal year 2021 that would widen a highway bottleneck and ease congestion. Applying for federal approvals and adding the project to the region’s broader transportation plans will require checking it still conforms to clean air standards. But if the rollbacks break the air board’s model, they can’t run those calculations.

“So that project is somewhat jeopardized,” Chesley said. “It’s arcane—I don’t go home at night and tell my wife about conformity findings … But it has a real impact.”

“Every day of delay costs money.”

In the Bay Area, plans to roll out new Bay Area Rapid Transit cars and extend the train to Silicon Valley could be put on hold. Projects to widen major Bay Area freeways—including Highway 101 across four counties—could stall, too. Randy Rentschler, director of legislation and public affairs for the Metropolitan Transportation Commission, cautions that major projects can stall for many reasons—and the federal rollbacks are just one.

“This is not necessarily the reason why a project might be delayed—but it certainly doesn’t help,” Rentschler said.

Darin Chidsey, chief operating officer of the Southern California Association of Governments, calculates $22 billion of transportation projects across six southern California counties could be delayed. That includes $6 billion to widen parts of Interstate 710 to curb congestion from trucks shuttling goods in and out of the ports of Los Angeles and Long Beach.

“Every day of delay costs money,” Chidsey said—citing costs to local residents stuck in congested commutes, to public agencies, and to the local economy. “$22 billion of projects translates into a lot of jobs, a lot of economic activity—it’s critical.”

“We want clean air. We want transportation projects. This rule works against both of them.”

From a back-of-the envelope-calculation, that could mean a hit to tens of thousands of jobs, according to Kiana Valentine, executive director for Transportation California—an advocacy group that represents labor and business in the construction industry. That’s extrapolated from the White House’s Council of Economic Advisers’ stat that “every $1 billion in federal highway and transit investment funded by the American Jobs Act would support 13,000 jobs for one year.” From that, Valentine said, “If we’re looking at putting at risk $130 billion, we anticipate that there would be some pretty significant impacts to construction jobs and the economy in the state.”

For now, transportation planners are in a state of limbo—anticipating a major setback, but not knowing when or how bad it could be.

“To do a lot of contingency planning is hard to do, because we don’t know what the final rule is going to say,” Caltrans’s Schmidt said. “We’re all concerned, and we’re trying to think about what might the ramifications be—but we don’t know that. And our hope is really that the rule doesn’t get finalized.”

San Joaquin’s Chesley agrees. “The headline is don’t make it tougher to do transportation improvements. It’s already tough enough as it is,” he said. “We want clean air. We want transportation projects. This rule works against both of them.”