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.
VMT
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.
California will let agencies pay for housing to offset increased driving
A new California law gives transportation agencies the option to pay into an affordable housing fund to offset the increased travel demand associated with major road projects. The approach could achieve several goals at once: mitigating emissions from highway expansions, creating a new funding stream for affordable housing, and helping more people live in accessible neighborhoods, reducing their transportation costs.
The benefits of transit extend well beyond transit riders
Public transit is often viewed by planners and transportation officials as a key strategy for reducing car dependency, easing traffic congestion, and lowering emissions. Every person who opts for transit over driving helps reduce the total miles driven in private vehicles. According to a large national study, however, good transit has a ripple effect on land use and travel behavior. For every mile not driven by transit riders, transit accounts for another six to nine miles not driven among the larger population.
Moving from LOS to VMT is more complicated than it might seem
Traffic engineers across the U.S. are accustomed to measuring road performance in terms of “level of service,” or LOS. Recognizing its unintended consequences, many transportation professionals and advocates have urged the industry to replace it with something better. However, LOS has become so ingrained in many processes that there is probably no single alternative to its use.
Telecommuting most likely increases travel
We’ve written before about the impact of telecommuting on travel demand. Contrary to some common assumptions, it often results in longer non-work trips or broader changes in travel behavior. As transportation agencies consider telecommuting as a viable strategy to cut travel—especially since the pandemic—a new comprehensive review presents mixed results.
Workers offset their commute travel when working from home
The massive shift to remote work during the pandemic altered the way many offices operate and increased interest in the potential for widespread telecommuting to help reduce traffic, transportation emissions, and other harmful impacts. We have reported several studies, however, that suggest remote work simply lets people drive at different times of day and for purposes other than commuting. A new study backs that finding.
To manage traffic, researchers ask: “Whose miles are these anyway?”
Several states and many local governments are growing more interested in measuring vehicle miles traveled (VMT) as a key indicator of transportation emissions levels and other unwanted impacts. But measuring VMT, especially at the local site level, can be more difficult than it seems. A new study in the Journal of the Planning Association points to data sources, shortcomings, and considerations for measuring VMT in the future.
State DOTs are key players in cutting transportation emissions
Through a combination of carrots and sticks—but mostly carrots—the federal government has encouraged state DOTs to take ambitious steps to lower the environmental impacts of transportation and to invest in more sustainable travel options. Two years into the Bipartisan Infrastructure Law (BIL), notes Adie Tomer at Brookings, it is still hard to know the impacts. Many states are still operating under the status quo. Others, however, including many SSTI partners, are seizing the opportunity to bolster ongoing local sustainability initiatives.
Success driving less
Driving less is one of the keys to reducing greenhouse gas emissions from the transportation sector, and to reducing the number of deaths and serious injuries on our roads. Most states have seen an increase in per capita vehicle miles traveled over the last 25 years. There are exceptions, however, where political action, multimodal investment, or the development of compact neighborhoods acted to pull VMT numbers down, says a new report by the Frontier Group.