Since the creation of the interstate system, the complex, swirling highway interchanges known as “spaghetti junctions” have successfully kept vehicles moving—but often left local neighborhoods behind in the process. Finding ways to heal the damage they’ve caused was the focus of a Minnesota Department of Transportation (MnDOT)-funded study led by CTS scholar Camila Fonseca-Sarmiento, director of fiscal research for the Institute for Urban & Regional Infrastructure Finance at the University of Minnesota’s Humphrey School of Public Affairs.
“Spaghetti junctions have improved connectivity and boosted regional economies. However, there is a growing recognition that communities near them pay the price in health, noise, and isolation,” Fonseca-Sarmiento says.
The hidden costs of connectivity are steep. According to the research team’s findings, these massive concrete barriers physically isolate and fragment once-vibrant neighborhoods, often destroying cultural landmarks along the way. Beyond the physical divide, residents face significant health risks from the resulting noise, air, water, and soil pollution. The financial toll is just as heavy, as property values drop and local businesses struggle when traffic is diverted away from street-level commerce.
Healing these community harms requires a level of creative planning that goes beyond traditional infrastructure design. The research team conducted in-depth case studies of eight different projects across the U.S. to see how other cities are tackling these issues. They found success in freeway cap parks that incorporate green space into deck-type structures built over highways, underpass parks that breathe life into the “dead space” beneath highway bridges, and infrastructure reconfigurations that thin out dense junctions to restore neighborhood connectivity. These projects “activate” the space surrounding highway infrastructure in a variety of ways—by including public art, walking paths, community gathering spots, recreational facilities, and programmed activities that bring people back together.
Interestingly, the case study analysis offered a surprise for the researchers. While they expected to find repeatable frameworks, policies, and engineering strategies, they discovered that human touch was the real secret to success. The most essential factors weren’t technical—they were relationship building, genuine community engagement, and a willingness to think “outside the box.”
“There was no one-size-fits-all engineering fix for mitigating community harms,” Fonseca-Sarmiento says. “And changes in practice were more important than changes in policy. This requires meaningful engagement—involving the public from the very beginning, empowering residents to share in decision making, and respecting local expertise on how to reach neighbors.”
To help MnDOT avoid these harms moving forward, the researchers developed a list of successful practices and recommendations. They urge officials to look beyond transportation to the overall livability of communities, collaborating with other sectors such as housing and parks. In addition, they compiled a comprehensive list of qualitative and quantitative indicators used across the various projects to ensure project benefits reach the residents and communities impacted by highway construction.
“The case studies from this work offer ideas, strategies, and guidance to enhance and improve how we address important issues pertaining to livability—and help offset some of the negative consequences of large infrastructure,” says William Goff, transportation planner with MnDOT’s Metro District and the project’s technical liaison.
The project’s final report offers a deeper dive into the case studies and a full list of recommendations.
—Megan Tsai, contributing writer
