A light rail train in Denver, Aug 6, 2019. In December, Colorado adopted a first-of-its-kind climate change regulation that will push transportation planners to redirect funding away from highway expansions and toward projects that cut vehicle pollution, such as buses and bike lanes. Denver has added several light-rail lines and express bus routes in recent years. (Terry Ratzlaff/The New York Times)

The highways in Colorado, one of the nation’s fastest-growing states, are frequently clogged with suburban workers driving into Denver, skiers heading high into the Rocky Mountains and trucks rumbling across the Interstates.

A Western frontier state with an affinity for the open road and Subaru Outbacks, Colorado’s traditional answer to traffic congestion could be summed up in two words: more asphalt.

But widening highways and paving new roads often just spurs people to drive more, research shows. And as concerns grow about how tailpipe emissions are heating the planet, Colorado is among a handful of car-dominated states that are rethinking road-building.

In December, Colorado adopted a first-of-its-kind climate change regulation that will push transportation planners to redirect funding away from highway expansions and toward projects that cut vehicle pollution, such as buses and bike lanes.

It is a big change for Colorado, which is reeling from devastating wildfires and droughts fuelled by global warming and where Denver and the Front Range often exceed federal ozone pollution standards, partly from vehicle exhaust. Under Gov. Jared Polis, a Democrat, the state aims to cut transportation emissions 40 percent below 2005 levels by 2030.

The rule marks a new front in the battle against climate change. Increasingly, experts warn that if states want to slash planet-warming emissions from cars and trucks, it will not be enough to sell more electric vehicles. They will also have to encourage people to drive less.

In a nation built around the automobile, that is not easy.

“It’s a tough shift for us,” said Shoshana Lew, executive director of Colorado’s Department of Transportation. “Colorado is very different from a place like New York City that already has lots of transit. But if we want to clean up our transportation system as quickly as possible, we need to try everything we can.”

More Roads, More Emissions

Over the coming decade, the decisions that Colorado and other states make about how many new roads to build could have major consequences for America’s ability to tackle climate change. Transportation is the nation’s largest source of greenhouse gases, producing 29 percent of emissions, and has been stubbornly difficult to clean up.

The new $1 trillion infrastructure law invests billions in climate-friendly programmes like electric car chargers and public transit. But it also gives states $273 billion for highways over five years, with few strings attached. One analysis from the Georgetown Climate Centre found that this money could significantly increase emissions if states keep adding highway lanes.

Already, there are signs that even states with ambitious climate goals like Washington, Illinois and Nevada hope to use federal funds to expand roadways, such as adding lanes to a congested section of the Eisenhower Freeway near Chicago. In 2019, states spent one-third of their highway dollars on new road capacity, roughly $19.3 billion, with the rest spent on repairs.

“This is a major blind spot for politicians who say they care about climate change,” said Kevin DeGood, director of infrastructure policy at the Center for American Progress, a liberal think tank. “Everyone gets that oil pipelines are carbon infrastructure. But new highways are carbon infrastructure, too. Both lock in place 40 to 50 years of emissions.”

The core problem, environmentalists say, is a phenomenon known as “induced traffic demand.” When states build new roads or add lanes to congested highways instead of reducing traffic, more cars show up to fill the available space.

Induced demand explains why, when Texas widened the Katy Freeway in Houston to more than 20 lanes in 2011, at a cost of $2.8 billion, congestion returned to previous levels within a few years.

“It’s not always intuitive to people, but the economic logic is pretty simple: If you make driving easier, people will do more of it,” said Susan Handy, a transportation expert at the University of California, Davis, who helped develop a calculator showing how highway expansions can increase emissions in different cities.

‘A Monumental Undertaking’

Some Colorado communities are wary of any shift away from traditional road-building. North of Denver sits Weld County, a largely rural region dotted with cattle ranches and oil wells where homebuilding has exploded in recent years, along with traffic. Local officials want new roads, including a $300 million proposal to add two lanes to a busy stretch of Interstate 25 linking Weld County’s swelling exurbs with Denver.

“We need more road capacity,” said Scott James, a Weld County commissioner. “And my fear is, this rule will either hobble funding for new roads or force us to spend millions on a bunch of buses or transit that just won’t work for us in rural Colorado. People move here from Denver or Boulder because they’re looking for a certain type of lifestyle. Are we going to punish them for that?”

Under the new rule, part of a $5.4 billion transportation package passed by the state Legislature, local governments will have to estimate the greenhouse gas emissions expected from future road projects, factoring in induced traffic. Those plans will have to adhere to an overall emissions budget: If localities want to expand highways, they need to offset the extra emissions with cleaner projects, such as public transit, bicycle trails, electric-vehicle chargers, carpooling or land-use changes that help limit suburban sprawl.

Enforcement is strict: If local governments exceed their emissions budgets, the state can withhold funding for roads. Colorado officials estimate the rule could shift $6.7 billion away from highways by 2050 and reduce driving miles by 7% to 12%, compared with business as usual.

Environmental groups hope the rule will force drastic revisions to long-planned highway expansions, like a proposal to widen a congested section of I-25 near low-income neighborhoods in downtown Denver.

“There’s a real opportunity to step back and rethink what we’re doing,” said Danny Katz, executive director of the environmental advocacy group CoPIRG. “If we need to make safety improvements to existing highways, we absolutely should. But let’s resist the temptation to keep widening roads and lock in a car-only approach.”

But business groups say Colorado has underinvested in highways for years, while adding 800,000 residents since 2010, and roads designed for an earlier era need to grow.

“We do think it’s likely that emissions will come down naturally as vehicle technology gets cleaner,” said Mike Kopp, president of Colorado Concern, a business coalition. “But in the meantime, people are stuck in traffic, it’s a truly immiserating experience, and we need to alleviate that.”

State officials are trying to thread the needle. Lew, who heads the Transportation Department, said in the short term she expected several key highway expansion projects to go forward, albeit with modifications. For instance, a $700 million plan to ease a bottleneck on Interstate 70 near Floyd Hill, where mountain-bound skiers jam the roads on weekends, will include a new “micro-transit” shuttle service offering an alternative to cars.

“There’s not a world where refusing to build another lane there would stop people from trying to go skiing,” Lew said. “But if we can put in a system of small buses that give people more choices, we can mitigate the impacts.”

The state faces major challenges: While Denver’s transit agency has added several new light-rail lines and express bus routes in recent years, ridership was declining even before the coronavirus pandemic scared people off buses and trains. And the regional organizations that propose transportation projects have limited control over local zoning rules that determine how densely cities develop and whether homes are built near jobs and transit stops. Those decisions can profoundly influence driving habits.

“We’ve been building communities oriented around cars and single-family homes pretty much since World War II,” said Andrew Gunning, executive director of the Pikes Peak Area Council of Governments, which oversees the rapidly growing region around Colorado Springs. “Trying to retrofit and change how we build those communities is going to be a monumental undertaking.”

A Growing Fight

While few states have copied Colorado’s approach, the pushback against highway expansions is slowly growing.

In Oregon, youth activists are protesting a $1.2 billion plan to widen I-5 through Portland, warning that the expansion will undercut the state’s climate goals. In Wisconsin, officials agreed to review a proposal to add two lanes to I-94 bordering a mostly Black neighborhood in Milwaukee after criticism from civil rights and environmental groups.

In Virginia, transportation planners had long agonized over traffic jams on I-95 between Fredericksburg and Washington. But after extensive study, they found that adding two extra lanes would cost $12.5 billion and do little to solve congestion. So last year, Ralph Northam, a Democrat who was governor at the time, announced a $3.7 billion deal to expand commuter rail service instead.

California has begun revamping its highway policies in an effort to curb car travel. Despite leading the nation in electric vehicle sales, the state is struggling to cut emissions because Californians keep driving more miles.

The state will now measure induced traffic during environmental reviews of new highways and plans to prioritize funding toward fixing existing roads rather than building new ones. Last year, officials halted a plan to widen the 710 freeway, which carries truck traffic from the port of Long Beach, over concerns that it would displace residents in low-income neighborhoods and worsen air pollution.

“The rhetoric we sometimes hear is that we’re trying to take away people’s cars or restrict their mobility,” said Darwin Moosavi, deputy secretary for environmental policy at the California State Transportation Agency. “But what we’re really talking about is giving people better and more convenient options so that they don’t necessarily have to drive everywhere.”

The Biden administration is also weighing in. In December, the Federal Highway Administration issued a memo urging states “to repair and maintain existing transportation infrastructure before making new investments in highway expansions.”

Yet the administration has limited authority to enforce this guidance, and state transportation officials have pushed back against restrictions on highway spending.

“Each individual state has unique challenges they need to address, and there’s not going to be a one-size-fits-all solution,” said Jim Tymon, executive director of the American Association of State Highway and Transportation Officials.

An early version of the infrastructure bill written by House Democrats would have curtailed states’ ability to fund highway expansions. But those provisions were removed in the Senate.

The law does include $90 billion for public transportation and $66 billion for rail. It also gives the federal Department of Transportation $114 billion in discretionary grants that could influence state plans. But ultimately, states have the final say.

“There’s lots of money for transit, but if new transit lines are surrounded by hundreds of newly expanded highways, how do we think that will work out for the climate?” said Beth Osborne, director of Transportation for America, a transit advocacy group. “The status quo is going to win unless everything aligns to change it.”

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