State Sen. Scott Wiener’s latest upzoning bill, Senate Bill 79, is bizarrely incompetent. The bill upzones huge areas around BART, Muni and other rail transit stops in a way that is impractical. In the coming decades, there will not be enough population growth to come close to filling these new transit-oriented development zones.
The bill is a good example of how we face the confluence of powerful landowners, sympathetic pro-growth newspapers publishers, and sycophantic legislators. SB 79 is billed as a measure to help keep public transit solvent, but in reality, it’s a land grab.
The bill only applies to seven counties in California, the four Bay Area counties of San Francisco, Alameda, San Mateo and Santa Clara, plus Los Angeles, San Diego and Sacramento. Three Bay Area counties, Contra Costa, Sonoma and Marin, were carved out of the bill by an added requirement that a county contain more than 15 rail transit stops. Orange County will most likely be included once it finishes its streetcar plan. These eight counties contain 59 percent of the state population.
It’s an article of faith in the Wiener/Yimby supply-side orthodoxy that California is suffering from a severe housing shortage. The business press no longer agrees. There is no question California is suffering from an affordability problem that includes the cost of housing—yet another problem that the state legislature has failed to address. But despite the prattle about supply and demand, the amount of housing in California and its affordability are distinct issues. Affordability is primarily a problem of grotesque income inequality in California and the rest of the nation.
To understand what is wrong with SB 79, we will need to dig into a bit of geometry, but nothing more sophisticated than what we learned in middle school. Let’s begin with the concept of the acre. Historically the acre has been defined as 10 square chains. The surveyor’s chain was 66 feet (22 yards) long. One square chain is 66 by 66 feet in area, or 4,356 square feet. An acre contains 43,560 square feet.
It helps to note that one square acre is 209 feet on a side. In Los Angeles and other cities, single-family houses often sit on plots of land 50 by 100 feet. Eight of these plots fit tightly into one square acre. An area of one square mile contains 640 acres.
SB 79 defines a “transit-oriented development zone” as the area within one half-mile of a “transit-oriented development stop.” In addition, the bill specifies a Tier 1 transit-oriented development stop as one “within an urban transit county served by heavy rail transit or very high frequency commuter rail.” In San Francisco, BART is an example of heavy rail transit, while some Muni streetcars qualify as very high-frequency commuter rail.
If we do the math (see footnote below if you want the details) this creates a potential population density in San Francisco of 119,893 people per square mile.
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Is this a realistic figure? Let’s compare that density to some well-known cities, in order from least to most populated:
Population density, persons per square mile:
San Francisco 17,726
NY City 28,217
Paris 51,940
Manhattan 73,291
Manila 116,079
San Francisco is the second most densely populated city in the United States, after New York. At zoned capacity, the population density of a Tier 1 development zone in San Francisco would be more than six times the average density of the city, or about the same density as Manila, the most densely populated city in the world.
The population of SF is 842,027. The city covers approximately 47 square miles. San Francisco has eight BART stations and three Caltrain stations, although the Bayshore station lies partly in San Francisco and partly in the city of Brisbane to the south. The entire population of San Francisco could fit into nine Tier 1 development zones, which would cover approximately seven square miles.
San Francisco also has 117 Muni stops, many of which are high frequency commuter rail stops, and under SB 79 would be the center of Tier 2 transit oriented development zones. Tier 2 zones have the same area as Tier 1 zones, but with 100 units per acre in the inner circle and 80 in the outer ring. At zoned capacity the population of a Tier 2 transit zone is 76,230 with a population density of 97,059 persons per square mile. The population density of Tier 2 transit zones lies between Manhattan and Manila. The entire population of San Francisco would fit in 11 Tier 2 stops at zoned capacity.
The absurdity of these Tier 1 and 2 development zones becomes obvious when they are compared to current forecasts of population growth for California counties and cities.
SB 79 is not necessary to accommodate growth in the Bay Area. The Dept. of Finance Demographics Research Unit’s most recent reports project that between the years 2025 and 2050 San Francisco will add 16,937 residents. In San Francisco, the projected population increase would fit in less than one-quarter of a Tier 2 transit zone surrounding a Muni stop.
Wiener justifies SB 79 by stating that it will help transit agencies balance their budgets by increasing ridership. But this is not realistic. BART and other transit agencies are facing insolvency in the next few years (see here and here). There is no way that SB 79 upzoning will create new buildings filled with transit riders in that time frame. According to this San Francisco Chronicle article, developers estimate that there will be little apartment building activity at least for 18 months, and only if rents jump 20 percent.
The bill is a cynical effort to resurrect Transit Oriented Development (TOD), an idea whose time has come—and gone. In the June 19, 2023 issue of the California Planning and Development Report, reporter Josh Stephens stated,
UCLA urban planning professor Michael Manville noted that the average resident of TODs, especially those that include large numbers of market-rate units, are not likely to use transit very often under the best of circumstances. Nonetheless, transit orientation gives developers a host of benefits—including density bonuses and, following the 2022 passage of AB 2097, the opportunity for significant parking reductions, all of which can make projects pencil out for developers.
SB 79 may be good for developers’ bottom line, but any resulting TOD projects probably add little additional transit use—because the rich people who will move into these expensive units don’t use transit anyway.
The bill fails to address the limits of upzoning. Upzoning gives developers an option to build higher and denser, but it does not require it. Nor does it make building taller economically feasible. The bill ignores the fact that building taller raises the cost per housing unit. As a recent study from the Terner Center points out, a 50 percent increase in height can raise the cost of an apartment building by 80 percent. Tall towers near transit will be too expensive for lower-income transit users.
Building more densely in Tier 1 and Tier 2 development zones will require major infrastructure upgrades. San Francisco already suffers from inadequate sewage treatment, a problem that occasionally floods the Bay with undertreated sewage and risks the health of swimmers and boaters and the other aquatic creatures who enjoy the Bay.
Regarding infrastructure issues in Los Angeles, City Attorney Hydee Feldstein Soto stated in a July 7, 2025, letter to Assembly Member Juan Carrillo, Chair, Assembly Committee on Local Government:
SB 79 clearly imposes billions of dollars from our local taxpayers for infrastructure expansion and remediation (e.g., water/sewer/stormwater systems, trash collection, road upgrades and signals, and power grid upgrades; first responder and mobility costs; environmental oversight costs; traffic, parking and livability impacts; and administrative and legal compliance costs) without constitutionally required reimbursement from the State.
Ironically enough, the excessive upzoning in SB 79 will do little or nothing to increase density in a useful manner. SB 79 is a land grab that will only benefit the developers who, over the next several years, will be able to build wherever they like in Wiener’s Tier 1 and Tier 2 development zones. As I stated in my comment on the bill in CalMatters:
The goal of upzoning should be to shape development so that taller apartments are built along transit corridors. This increase in density creates more foot traffic on the street, allowing shops and restaurants to thrive. It also increases the number of commuters who can easily be served by transit. Too much upzoning, like that proposed by SB 79, will allow developers to spread out buildings over a wide area, randomly dotting the landscape with expensive apartment towers. This does nothing to bring about the benefits of urban density.
It might take decades, if ever, for parts of Wiener’s development zones to get near the population density of Manila. In the short run what we are likely to get is something more like Houston, a messy city with little formal zoning. There tall towers poke skyward next to suburban single-family homes. Freedom from planning constraints has led to traffic jams and flooding in neighborhoods that should have never been built. Contrary to Yimby mythology, lack of planning has not made housing cheap in Houston. The percentage of renters who are housing cost-burdened there is higher than the national urban average, and much higher than that of San Francisco.
I’ve often joked that the ultimate goal of Wiener’s housing bills is to turn the built environment into a free-fire zone for real estate capital. With the passage of SB 79, the joke no longer seems very funny. But ultimately, the joke is on us.
California already has a complex, expensive and time-consuming planning process known as the Regional Housing Needs Allocation (RHNA). All 540 cities and counties in California are required to re-evaluate their zoning plans every eight years. Those RHNA goals are often wildly excessive and impossible for cities like San Francisco to meet. It is unclear at this point how the Department of Housing and Community Development will harmonize SB 79 with the existing RHNA planning process.
Drawing circles around transit stops is not a useful form of planning. Mistakes in the built environment last for decades, often outliving their perpetrators. Long after Wiener has been termed out and is enjoying whatever sinecure his powerful benefactors will arrange for him, the legacy of his recklessness will live on. Cities will be left to do the damage control.
With well-funded sycophants like Wiener in power, the interests of most Californians are neglected. It’s disturbing that a majority of legislators in Sacramento chose to enable him by passing SB 79. Wiener has been the main architect of the state legislature’s failed housing policy. With the passage of about 250 housing bills in the last several years, the legislature has created a legal Tower of Babble that grows more incoherent every legislative session. SB 79 is the latest addition. Sacramento’s “housing policy” is an oxymoron. It’s keeping lawyers employed, but builders? Not so much.
Regardless of how much damage is caused by Sacramento’s dysfunction, it is difficult to make California residents notice. Right now, the disastrous Trump administration is monopolizing America’s attention span. But even with Trump in charge in Washington, DC, California residents need to pay attention to what goes on in the state legislature. The news from Washington, DC is terrible, but that’s no excuse to give Sacramento a pass.
To find out how your legislators voted on SB 79, go here. To find and learn more about your senator and Assembly member, go here and here.
The math: The diagram below shows a hypothetical Tier 1 stop. The black box is a one square-mile area of 640 acres. Inscribed inside the square, just touching its edges, is a red circle. This is the area of SB 79’s Tier 1 development zone, the area within a half- mile radius of the center.
The area of a circle with a radius of one-half mile is pi/4 square miles, or 0.7854 square miles. The red circle contains 503 acres. The area within the blue circle is within one-quarter mile of the center and has an area of pi/16 square miles, or 126 acres. Finally, the ring between the red and blue circles occupies 503 – 126 = 377 acres.
Now that we know the acreage of a Tier 1 transit development zone, we can calculate how many housing units can be placed inside it, and what the population would be at its zoned capacity. Let’s show this in a series of steps (we have already completed the first step):
Step 1: Calculate the areas of a Tier 1 transit zone: 126 acres for inner circle, 377 acres for outer ring.
Step 2: To compensate for land used to provide streets and sidewalks, reduce the figures above by 15 percent. That leaves 107 acres for the inner circle, and 320 acres for the outer ring suitable for housing production.
Step 3: To calculate the number of housing units note that SB 79 requires cities to allow a minimum of 120 units per acre in the inner circle, and 100 per acre in the outer ring. That’s 12,840 housing units in the inner circle, and 32,000 in the outer ring, for a total of 44,840 housing units.
Step 4: Calculate the population of the Tier 1 development zone assuming the San Francisco average of 2.1 persons per household. That’s a population of 94,164.
Step 5: Calculate the population density of the Tier 1 development zone in persons per square mile: (Divide 94,164 by pi/4). The population density is 119,893 persons per square mile.
