Nearly every state DOT is grappling with how to reduce traffic and carbon emissions—many states developed official , and congestion relief is often at the top of a DOT’s priority list. But a new study from Swedish researchers says that some of the most common ways to address these challenges—using only “carrots” rather than “sticks,” in the researchers’ words—may leave states struggling to achieve their goals.
Research
Caltrans review finds outdated and misunderstood models hinder project analysis
In California, where travel demand models often guide project-level decisions and analysis, a new report finds many are outdated, poorly documented, and ill-suited to the purposes agencies sometimes use them for. Transportation agencies rely on models to forecast traffic and guide billions of dollars in infrastructure investment. Without updates, these tools risk locking in old assumptions about growth and travel behavior rather than helping agencies plan for a more sustainable and efficient future.
Repairing highways is better for the economy than expanding them
The U.S. faces a $1 trillion backlog of roads and bridges needing repair, according to FHWA. Yet we still spend roughly $27 billion per year (25% of the total) expanding and building new highways. Mounting evidence shows that shifting those dollars toward maintenance and rehabilitation could yield greater benefits.
Despite efficiency gains, rising travel demand pushes emissions higher
Advances in technology have made transportation more energy efficient in recent decades, lowering emissions per mile and per unit of freight. But according to a new study, those efficiency gains haven’t been enough to offset the rise in emissions from new transportation demand. To hold transportation emissions steady going forward, the study says, global transportation demand must not continue rising, or we must make a more dramatic shift toward electrification than currently imagined.
More transit means safer streets
To reduce traffic deaths, public transit should be seen as a core part of safety infrastructure, not just an alternative mode of travel. Every day, thousands of car crashes occur in the U.S., resulting in injury or death, yet they receive far less attention than the much rarer crashes involving public transit. For city planners working to reduce roadway fatalities, understanding how these perceptions influence travel choices is critical.
Driving trips are dropping, especially among young people
For years, people wondered whether travel would bounce back after the pandemic. The latest FHWA data, along with other new research, gives a clearer answer. Growth has slowed. In 2024, total vehicle miles traveled (VMT) finally inched past its 2019 peak, but by only 0.5%. On a per capita basis, Americans are still driving less, down 2.3% since 2019.
Emotional perceptions can be a tool for predicting street safety
How a street feels can matter just as much as how it’s physically built. A new study shows that emotional perceptions about whether a street seems inviting, secure, or rundown can help explain safety for people walking or biking—a reminder that planners should think beyond conventional design standards. Road designers should also consider the character and aesthetics of the spaces they create.
Complex urban streets encourage safer driving
Reducing excessive speeding is one of the most effective ways to improve road safety—especially where people are walking or biking. While lowering speed limits and adding traffic calming measures help, growing research highlights the value of self-explaining streets that give drivers constant cues to slow down.
Pedestrian deaths aren’t accidents, they’re policy failures
Pedestrian deaths are rising faster in the U.S. than in any other high-income country. A decade-long surge, up 50%, has made the U.S. the most dangerous place to walk among 27 peer nations. Many experts view these deaths not as random accidents but as preventable tragedies that reflect deeper policy failures in transportation, infrastructure, and public safety.
Cutting transit wait times is key for winning back ridehail users
Nearly all trips taken in some cities by ridehail services, such as Uber or Lyft, could be taken by transit, according to new research. That means the excess traffic those trips create could be prevented, with the right incentives. To encourage people to opt for transit instead of ridehail, transit agencies can pursue strategies to shorten walk and wait times associated with transit.