A San Francisco Chronicle article highlighted research findings by Urban Planning Associate Professor Adam Millard-Ball on the width of streets in San Francisco. In places with housing shortages, wide streets take up valuable land that could have been used to build more homes or other buildings, Millard-Ball said. While the average street in San Francisco is 50 feet wide, Millard-Ball proposed 16 feet as the functional minimum width for residential streets. In some areas of the city, streets are an average of 93 feet wide. Millard-Ball argued that in high-cost California counties like Santa Clara and San Francisco, the consequences of unnecessarily wide streets are enough to make the costs to narrow them worth it. For cities that are still growing, Millard-Ball suggested that planners build narrower streets to save land for housing. In established cities where narrowing the streets is not feasible, he proposed adapting unused street spaces into outdoor dining spaces, slow streets and other recreational spaces.
Associate Professor of Urban Planning Adam Millard-Ball joined an episode of Malcolm Gladwell’s podcast “Revisionist History” to discuss the future of autonomous vehicles. The safety of autonomous vehicles was originally framed as a technological challenge that required a programming solution, but the main issue is actually the people outside the vehicle, Millard-Ball explained, beginning at minute 26:50. “If you are a pedestrian and you have that confidence that the autonomous vehicle is going to stop and yield to you as it legally should, then there is nothing to stop you from taking the right of way,” he said. Autonomous vehicles are programmed to maximize caution, which allows the pedestrian to make the first move instead of waiting to see what the car will do. “The more unpredictable a pedestrian appears, the autonomous vehicle will recognize that unpredictability and be more cautious,” he explained. Autonomous vehicles allow for a role reversal where the vehicle caters to the pedestrian’s erratic behavior.
By Clark Merrefield
The Journalist’s Resource
With cities and suburbs across the United States facing well-documented affordable housing shortages, researchers for years have studied how government planning standards affect housing costs.
Those studies often examine how planning and zoning decisions affect traffic noise, whether neighborhood amenities can be reached by foot and other factors that can make a home more or less valuable.
A new paper expands this body of research by considering the housing, schools, parks and other infrastructure that go unbuilt in favor of wide streets.
The U.S. has some of the widest streets in the world. In 20 of the most populous counties, the median residential street plus sidewalks is 50 feet wide, with the dollar value of land used for streets sometimes stretching into six figures, according to the research in the Journal of the American Planning Association.
Wide streets are less common in some other countries. Certain streets in Japan, for example, are much narrower. Developments in Tokyo since 1990 have average street widths of 16 feet, noted Adam Millard-Ball, an associate professor of urban planning at the UCLA Luskin School of Public Affairs and author of the new paper.
“One of the best ways to alleviate the housing crisis is to build more housing,” he said. “To the extent that narrower streets allow developers to build more housing, that will address the No. 1 issue with housing right now.”
The median residential street in Arizona’s Maricopa County, which includes Phoenix, is 50 feet wide, according to Millard-Ball’s sample of counties.
The median width of a residential street in Middlesex County, Massachusetts, which includes Cambridge, is 40 feet — the narrowest of the group.
The widest streets in the sample are in Cook County, Illinois, which includes Chicago. There, the median residential street is nearly 65 feet wide.
The 50-foot standard
For urban planners, a street is called a right of way. The paved section is the roadway.
A right of way includes the roadway as well as sidewalks, if any, along with space for drainage, utility poles and other public infrastructure. It’s the land usually owned by a city or county that the public has the right to use and make its way through by car, bicycle, foot or other mode. Neighbors waving hello across the sidewalk’s edge of their properties are waving across the right of way.
The median 50-foot right of way Millard-Ball documents stems from nearly a century of history in U.S. planning. After the home mortgage system collapsed during the Great Depression, the federal government stepped in and established the Federal Housing Administration in 1934.
The agency’s mortgage insurance and financial assistance for homebuyers represented “the most ambitious suburbanization plan in United States history,” wrote Michael Southworth and Eran Ben-Joseph in a 1995 Journal of the American Planning Association article that reviews the historical rise of U.S. suburbs.
To protect the government’s unprecedented investment in home ownership, mostly for white Americans, developers had to have detailed plans approved by the agency. The agency encouraged cul-de-sacs for new developments and favored plans that discouraged through traffic.
“Moreover, the FHA, unlike other planning agencies, was largely run by representatives of real estate and banking, so developers felt that its intervention protected their interests,” Southworth and Ben-Joseph wrote.
If developers wanted to build homes that would benefit from federal financial backing, rights of way had to be at least 50 feet wide, Millard-Ball explained in his new paper, “The Width and Value of Residential Streets.”
To understand the value of land used for streets, Millard-Ball drew on research from the Federal Housing Finance Agency that estimates the value of quarter-acre lots zoned for single-family homes across the country. The value of the land used for streets can be substantial in places where low population density and high housing costs converge.
Santa Clara County, California, which includes San Jose, has the most valuable streets in the sample at $146,000 per tax parcel. That’s roughly 40% of the median price of an existing single-family home sold in the U.S. in April 2021, according to data from the National Association of Realtors.
“One of the best ways to alleviate the housing crisis is to build more housing. To the extent that narrower streets allow developers to build more housing, that will address the No. 1 issue with housing right now.”
— Adam Millard-Ball, UCLA Luskin
New York City, by contrast, has high housing costs but also high density — large apartment buildings are common. Tens of thousands of people live within each square mile. The land beneath streets in Queens, for example, is worth $36,000 per parcel.
At the other end of the value spectrum, streets are worth $7,000 per parcel in Bexar County, Texas, which includes San Antonio. But land values and street widths can vary greatly within counties.
Terra Vista, a small street in a subdivision 25 miles north of San Antonio, is 52 feet wide and has a land value of $43,288 per parcel. All the land under residential streets in Millard-Ball’s 20 counties is worth nearly $1 trillion in total.
Millard-Ball noted that street land value estimates per parcel are likely low for high-cost, dense cities, which often zone for multifamily buildings over single-family homes.
For example, an Italian specialty food store in the Mission District of San Francisco sold its parking lot for $3 million in 2018 — roughly $36 million per acre, by Millard-Ball’s calculation — to make way for a five-story, 18-unit building, according to the news site Mission Local.
Most U.S. counties regulate how and where new housing and business developments are built, according to the National Association of Counties, a nonprofit organization that represents U.S. county governments.
Many large cities do the same.
It would be overly costly for cities and counties to change the width of existing streets, particularly with local governments facing budget shortfalls during the pandemic.
Still, the estimates in the new paper can be instructive for planning officials in places like Bexar, one of the fastest growing counties in the U.S., as they permit developments to accommodate new and current residents.
“The values are an indication that cities should be making it easier to use streets for something other than roadways and parking,” Millard-Ball said. “A good analogy is that during COVID, one use of streets has been for outdoor dining. It’s recognition that this land is more valuable to the community if we can use it for people to get together and eat in a safer environment outdoors, than as a parking space or travel lane for cars.”
He continued: “The point is that desolate asphalt is doing nobody any good — not the city, not property owners, not anyone. Cities are often keen to widen the right of way with new developments. Say you want to develop a new apartment building. Often, the city will say, ‘Sure, but you have to give up some land so we can add a turn lane, or widen the sidewalk.’ If cities can widen the right of way, why can’t they narrow it in exchange for improvements that will benefit the public?”
Indeed, when a new residential building goes up, cities commonly require developers to widen streets, according to a 2017 paper in the Journal of Transport and Land Use by Michael Manville, another UCLA Luskin urban planner.
In the paper, Manville looked at how the requirement played out in Los Angeles from 2002 to 2012. He found the city’s predictions of increased traffic with the arrival of new buildings were often wrong, and “the standards the law is based on are in some ways unverifiable. Thus the law likely does little to reduce congestion and probably impedes housing development.”
City and county planning standards vary and change, but the federal 50-foot standard still often dominates residential street design. Still, it’s not always true that counties with more land to expand, like those in Texas, have wider streets. Dallas County, for example, specifies that new residential streets in subdivisions be at least 50 feet wide. The median width of residential streets there is exactly 50 feet, Millard-Ball finds.
Residential streets in Chicago, meanwhile, are typically 66 feet wide, according to city design standards. That roughly matches the length of the typical surveyor’s chain as the city grew throughout the 1800s and early 1900s. The surveyor’s chain was a tool made up of interlocking metal bars that land surveyors used to measure and mark the shapes of streets to be built.
Uniformity in street design made sense as the nation was expanding and infrastructure technologies were less advanced. But the takeaway for Millard-Ball is that maintaining rigidity in street design means fewer amenities and, potentially, less housing.
He wonders, for example, whether more streets could be built with parking cutouts only where there are no private driveways — providing a unique residential landscape alongside opportunities to use more of the built environment for activities other than driving.
“That would make construction drawings more complex,” Millard-Ball said. “The tradeoff is visual interest — and saving a lot of valuable land.”
The prospect of narrower streets raises the question of whether emergency vehicles would be able to pass, though some planners, and at least one report from the U.S. Department of Transportation, suggest smaller emergency vehicles could be an answer.
Associate Professor of Urban Planning Adam Millard-Ball spoke to Bloomberg CityLab about his research on the land value of streets in the United States. Millard-Ball calculated the widths, land areas and land value of streets in 20 different counties in the U.S., and he found that streets averaged 55 feet wide, even in residential areas with low traffic. Streets are much wider in the United States than in other parts of the world. In the counties he surveyed, Millard-Ball found that streets took up 18% of the total land area. He said cities could use some of the land currently allocated to streets for bike lanes, transit, green spaces or housing. He also noted that decreasing standard street sizes could help reduce housing development costs. “People are already using streets for housing, just not in a sanctioned way,” he said. “Why do we rule out 20% of a city’s land and declare it off limits for that?”
Associate Professor of Urban Planning Adam Millard-Ball spoke to the San Francisco Chronicle about housing developments planned for parts of California that are prone to wildfire. The state Attorney General’s Office has opposed some of these developments, arguing that they pose grave danger in an era when uncontrolled wildfires threaten the state. The article notes that devastation in places like Santa Rosa, Paradise and Redding, in the so-called wildland-urban interface, has underscored how suburban sprawl is not only a target of fire but fodder for it, hastening the speed and intensity of blazes. Limiting development, however, can frustrate growth plans of small towns and cities and undermine progress on the state’s housing crunch. “There are really these twin concerns coming into conflict now,” Millard-Ball said. “The state’s housing crisis makes it an imperative to make it easy to build housing. At the same time, there’s the threat and tragedy of wildfires.”
Recent articles in Medium and Sightline highlighted the findings of Associate Professor of Urban Planning Adam Millard-Ball’s new research on the relationship between parking and driving in cities. While many cities have been designed under the assumption that the urban environment should accommodate people’s desire to drive, researchers led by Millard-Ball found that that assumption is backward. “Increased parking causes more car ownership and more driving while reducing transit use,” the team concluded, noting that “buildings with at least one parking space per unit have more than twice the car ownership rate of buildings that have no parking.” The Sightline piece cited Urban Planning Professor Donald Shoup’s observation that parking spaces are a “fertility drug for cars.” Furthermore, the research team found no correlation between parking supply and employment status, indicating that buildings with less parking do not limit the job prospects of their occupants.