It’s federal transportation policy season, with the House and Senate advancing bills to fund federal surface transportation programs for the next five years. That makes it a great time to reflect on the social and environmental impacts of our transportation policy.

For decades, the federal government has spent 80 percent of transportation infrastructure funds on highways, with only 20 percent left for public transit. Such lopsided spending leads to serious adverse consequences.

Transportation is the largest and fastest-growing source of U.S. greenhouse-gas emissions, ahead of even coal or gas-fired power plants. Vehicle tailpipes also emit other toxic pollutants including nitrogen oxides. These are serious health hazards, especially for the poor and people of color, who are disproportionately exposed.

Our transportation system kills people more directly as well. Roadway deaths climbed from 33,000 in 2010 to more than 36,000 in 2019, with the growth mostly driven by pedestrian fatalities.

Our government’s 80-20 policy is subsidizing sprawl and traffic, even as traffic deaths and pollution keep rising. Meanwhile, it underfunds mass transit, passenger rail and pedestrian and bicycle safety.

Because it relies on people owning and operating personal vehicles, our current transportation system leaves out millions of Americans who can’t afford a car, or can’t operate one because of age or disability. It excludes the nearly one-third of Black households – and nearly 38 percent of low-income households – that don’t own a car.

The transportation funding bill proposed by the House Transportation and Infrastructure Committee makes incremental improvements, such as requiring states to demonstrate that they have at least considered alternatives, including expanding public transit systems, before using federal funds to expand highway capacity.

And a bill introduced by Rep. Hank Johnson, a Georgia Democrat, would provide $20 billion a year in federal funding for transit operations.

Traditionally, the federal government has funded the construction of transit infrastructure, but not its operation. That’s left states and transit agencies to fund operations entirely on their own, often overrelying on regressive revenue sources such as fares. Federal operational funds will help transit agencies make service improvements (such as more frequent and reliable bus operations) that riders really need.

Rep. Chuy Garcia, an Illinois Democrat, offered amendments to the House transportation bill to expand and electrify transit and create funding parity between highways and transit. Unfortunately, these amendments didn’t make it into the bill, but Garcia got a verbal commitment from House leaders to continue working with him on his proposals. They should be pressured to keep that commitment.

But none of this goes far enough.

The truth is, we need a freeze on all highway expansion, except under the rarest circumstances (for example, expanding evacuation routes out of disaster-prone areas).

To the extent that we’re spending federal money on roads, we should be investing in pedestrian and bicycle safety infrastructure and repairing structurally unsound bridges. And aid for other roadway maintenance, such as repairing potholes, should be conditioned on a highway expansion freeze.

Expanding highways to alleviate congestion is a losing proposition, because growing capacity leads to growing traffic, a phenomenon known as “induced demand.” And this, of course, leads to more pollution, carbon emissions and traffic deaths.

Instead, we should stop subsidizing sprawl and spend those savings on our resource-starved mass transit systems. Currently, as many as 45 percent of Americans have no access to public transit. Many of the remaining 55 percent may only have access to a bus that runs once every hour and stops running by 6 p.m., perhaps only on weekdays.

Like new fossil fuel pipelines, we need to start making highway expansion politically toxic. Let’s dump highways and invest in transit.