Norman Garrick and Wesley Marshall are assistant professors of engineering at the Universities of Connecticut and Colorado, respectively, and they are making names for themselves among the anti-cul-de-sac crowd.

In prior research, Marshall told me, they found that in the most extreme cases “older, denser, connected cities were killing three times fewer people than sparser, tree-like cities on an annual basis." Of course, people walk and bike more in dense cities, but the research on actual ties to health outcomes is scant. So Garrick and Marshall, along with Daniel Piatkowski at Savannah State University, took on and have just completed a large study of how street networks might influence our health.

They looked at the three fundamental measures of street networks—density, connectivity, and configuration—in 24 California cities, and compared them with various maladies. In the current Journal of Transport and Health, Garrick and Marshall report that cities with more compact street networks—specifically, increased intersection density—have lower levels of obesity, diabetes, high blood pressure, and heart disease. The more intersections, the healthier the humans.

“It might not be common for people to explicitly contemplate health when selecting a place to live,” Garrick and Marshall write, “but this research indicates it is worth considering.”

And people are starting to consider it.

The original city design was really no design at all. Known as “organic,” it is the medieval pattern we see throughout many of Europe’s haphazardly still-thriving cities. Then, for centuries during and after the Renaissance, the rectilinear grid was the gold standard in city design. But in the twentieth century came what Garrick and Marshall call a complete overhaul—a shift toward the branching tree model of the modern subdivision, which was optimized for the great horseless carriage.

Centuries of compact and connected cities rapidly gave way to sparse, dendritic, “hierarchical” street networks. These layouts afforded the luxury of a quiet cul-de-sac with space for miniature mansions and lonely pools in every backyard. As Emily Badger at CityLab recounted in a merciless takedown of the cul-de-sac, the U.S. Federal Housing Authority published technical bulletins in the 1930s that “painted the urban street grid as monotonous, unsafe, and characterless.”

As with people, calling a neighborhood characterless cuts even more deeply than calling it unsafe.

Illustrations of grid neighborhoods and hierarchical neighborhoods in said pamphlets bore the labels “bad” and “good.” The FHA’s design preferences “evolved into regulation. From the 1950s until the late 1980s, there were almost no new housing developments in the U.S. built on a simple grid.”

Garrick and Marshall have also previously found that people who live in more sparse, tree-like communities spend about 18 percent more time driving than do people who live in dense grids. And they die more readily—despite old research that implied otherwise. Studies from the 1950s looked at safety in cul-de-sacs and found, as Marshall put it, “You'll have fewer crashes in the cul-de-sacs. Sure, you're safer if you never leave the cul-de-sac. If you take into account the entire city, your city might be killing more people." I got the impression he could go on about cul-de-sacs. 68 percent of Americans are overweight or obese, which means that someone you know is overweight or obese. Most people don’t get the CDC’s minimum recommended amount of physical activity. Americans spend more time driving every year. So it is logical to conclude, as Garrick and Marshall do in their paper, “The role of the street network and how we put together the bones of our communities should not be overlooked as a potential contributing factor to health outcomes.” They also found that wide streets with many lanes are associated with high rates of obesity and diabetes. That’s most likely indicative of, as Garrick and Marshall put it, “an inferior pedestrian environment.” Similarly, so-called “big box” stores in a neighborhood indicate poor walkability and are associated with 24.9 percent higher rates of diabetes and 13.7 percent higher rates of obesity. Dense cities promote walking and biking, so the push for healthier cities fits with the vogue push for active lifestyles—as opposed to gym routines smattered across an indolent existence. Physical activity is not just concerted exercise time and deliberate recreation. It’s about ways of life. For some people, that’s best accomplished by making things inevitably more difficult on themselves in everyday life. “Taken together these findings suggest a need to radically rethink how we design and build the streets and street networks that form the backbone of our cities, towns, and villages,” Garrick said in a press statement. “This research is one more in a long line that demonstrates the myriad advantages of fostering walkable places.” "It's nice to make more of these connections,” Marshall told me, tonally foreshadowing the inevitable correlation-is-not-causation caveat, “but it's hard to say that these kinds of neighborhoods cause good health." It’s true that people who like to walk and bike might be choosing to live in denser neighborhoods, and that may be all there is to this relationship. But on that note, there a lot of people who don't really have a choice where they live. They can't afford to live in the hearts of big grid cities. “A lot of poor people are getting forced out of the walkable urban scene,” Marshall said. In a reversal of the 1950s' “white flight,” many cities are seeing gentrification that is pricing out poor neighborhoods. Others stranded are kids, who often don't realistically have the option to walk to school. They have to get on a bus. So are health factors influencing city planning? "There is a push in that direction, but I still wouldn't say it's really integrated into what people are doing,” Marshall said. “If you're looking to buy a new house, I think very few people are cognizant that there might be long-term health differences between one neighborhood and the other. You might hear about it in terms of things like fracking or living near a highway. The obesity epidemic is becoming a national crisis, but almost nobody connects that with neighborhood design. The connections we're making there are all about food and exercise. But if we build neighborhoods where exercise is part of people's daily routine, you would think that could go a long way." Indeed. “Life is a bunch of intersections,” I said. But I don’t think he heard me.