Every weekend in San Francisco, the Upper Great Highway, a four-lane thoroughfare that runs along Ocean Beach from Lincoln Way to Sloat Boulevard, is closed to cars. Cyclists and skaters cruise the pavement, and pedestrians stroll as they please.
On Mondays, traffic resumes its normal rhythms and the roadway again becomes a highway. But a ballot measure in this election cycle could close it to vehicular traffic for good.
If San Franciscans support Proposition K, the two-mile stretch of the Upper Great Highway will turn into an oceanside park that would give walkers and those who bike, scoot, and skate full access to the space, full time.
Prop K opponents say permanent closure would clog surrounding Sunset District streets with diverted traffic, cut off coastal access for people who depend on cars, and harm the environment. But by and large, city and state officials aren’t buying these arguments.
In a sense, SF voters have already rejected them as well. Two years ago, 63 percent of city voters approved a measure to ban cars permanently from 1.5 miles of JFK Drive in Golden Gate Park, creating a public space for car-free commutes, art, events, and recreation.
At the same time, 65 percent of voters rejected a competing initiative that would have opened JFK and other park streets – and returned the Great Highway to cars full-time. This year, Prop K tests that appetite again, without the complication of the Golden Gate Park closures. We are also two more years removed from the pandemic, which spurred such an immediate thirst for more open space.
The Great Highway extension
Whatever happens with Prop K in November, a separate part of the Great Highway – known as the extension, which runs past the SF Zoo from Sloat to Lake Merced – will soon be replaced with land, sand, vegetation, and a bike and pedestrian trail.
These changes are meant to protect a major wastewater plant from sea-level rise and beach erosion, which had already eaten into the road during a series of El Niño storms a decade ago. Construction is scheduled to begin in late 2025.
Erosion and weathering are taking a toll on the Upper Great Highway as well. Blowing sand closes the road to traffic an average of 32 times per year, racking up annual maintenance costs of $350,000 to $700,000, according to the San Francisco Municipal Transportation Agency (SFMTA).
If it remains a highway, the asphalt will soon need repairs and traffic signals will need upgrades, which the SF Controller estimates could cost up to $1.7 million. If Prop K passes (it needs a simple majority), backers say the cost of conversion to a park can be covered through fundraising, and they’ve been brainstorming with people who brought the Presidio’s Tunnel Tops to life.
4,000 visitors
The current weekend closure is part of a pilot program that expires in December 2025. The pilot has allowed SFMTA and the SF Recreation and Park Department to track usage and traffic patterns.
The closed road sees 4,000 people per average weekend day, making it the third most-visited open space after Golden Gate Park and the Marina, according to Rec and Park.
Sup. Joel Engardio, whose district includes the Great Highway, helped put Prop K on the ballot. “Just by closing the gates, this park is one of the most used places – at no cost,” he says.
Increased delays are negligible for the most part, according to SFMTA, but the agency acknowledges the need for work to improve flow in some key areas.
The big picture: for weekend drivers diverted from the Great Highway to other streets, travel time is up about three minutes over peak weekday travel when the road is open to cars.
SFMTA also drilled down on traffic on nearby streets that are always open but take in diverted traffic. Trips on Lincoln Way and Lower Great Highway (a parallel residential street, open to cars and not part of the proposed closure) are about one minute longer on weekends than during weekday peak times.
The closure led Lower Great Highway residents to complain about speeding cars, and SFMTA has responded by installing speed cushions – a milder version of a bump – and other safety measures.
Other than the Lower Great Highway and Lincoln, however, SFMTA says traffic volume on other streets has “minimal variation” between weekends and mid-week.
Sunset, Lincoln, and Sloat
Prop K opponents say full-time closure will be dangerous as rerouted weekday drivers seek alternate routes. At a forum hosted last month by radio station KALW, Open the Great Highway campaign spokesperson Richard Corriea said, “People are having accidents on Sunset Boulevard and 19th Avenue already” – the two other main north-south arteries in the Sunset District. “We’re just going to add to that.”
SFMTA says street improvements on surrounding roads, including Sunset, Lincoln, and Sloat, are in the works and will address some of these concerns. (The Sloat reengineering is necessary no matter the fate of Prop. K because of the Great Highway extension closure.)
(19th Ave. is already part of the city’s high-injury network – the 12 percent of streets where most crashes happen – but Sunset Blvd. is not.)
The agency acknowledges that some frequent Great Highway users — drivers from the Richmond District to areas south of Sloat, including San Mateo County — see choke points at three intersections. It currently plans to ease traffic flow at one of them, on Sloat Boulevard north of the SF Zoo. (When the Great Highway extension closes permanently next year, use of this intersection will increase even more with drivers heading to Daly City.)
Sup. Connie Chan, who represents the Richmond, said at the KALW forum that Prop. K moves too fast. Road and public transit upgrades should come first, she said. “We [should] have north-south access first before we close another road.”
SFMTA says the on-again, off-again nature of the pilot makes studies more difficult than a temporary full closure would.
Prop. K opponents say city data are incomplete, or they simply don’t trust it. Despite a county transit authority report saying a closure wouldn’t affect emergency response times, Corriea, a former police officer, insisted otherwise at the KALW forum.
Opponents are also doubling down on other arguments, despite public rebukes.
Wrong on three counts
People who want to keep the Great Highway open to cars have pleaded their case to at least three different agencies, all to no avail.
In late 2023, the Planning Commission approved a special coastal-zone permit for the pilot project. Opponents, led by the Sunset-Parkside Education and Action Committee (SPEAK), took the case to the SF Board of Appeals in February 2024.
SPEAK argued that the weekend closure violated state public coastal access laws. The board rejected the argument, so SPEAK said it had new evidence that the closure caused environmental harm. The board refused to grant another hearing.
SPEAK had one last appeal: the California Coastal Commission, which is tasked with protecting California’s coastal areas from environmental degradation and maintaining public access.
In April, SPEAK tried to convince the commission that the closure restricted public coastal access, made surrounding streets unsafe, and harmed the sensitive sand dune ecosystem. The commission rejected all three arguments.
The commission’s subsequent report (click link for May 9) detailed flaws in SPEAK’s case. People who access Ocean Beach by car still have parking adjacent to the closed road, the commission wrote. And the closure actually makes beach access safer for pedestrians.
The commission’s most stinging critique focused on SPEAK’s environmental argument, which cited a 2023 Estuary Institute report on Ocean Beach’s “escalating dune erosion, primarily due to human-induced factors like informal trails.” SPEAK tried to blame these effects on the increase in foot traffic the area has seen since the pandemic.
But the commission slammed the group for taking this out of context. The Estuary Institute found dune degradation dates back to at least the 1990s and couldn’t be pinned on the closure pilot.
In its current campaign, Open the Great Highway has rehashed the SPEAK arguments through social media and YouTube. The group declined The Frisc’s requests for comment.
‘It’s so unparalleled’
Heidi Moseson is vice president of Friends of the Great Highway, a firm supporter of Prop K. For Moseson, the issue is personal. She regularly walks the highway with her mother, who has rheumatoid arthritis and uses a cane. The flat surface allows her to safely walk near the beach. “So many people get to enjoy the coast – it’s so unparalleled,” says Moseson.
If Prop K passes, Moseson says her group and others will begin fundraising for park amenities. She says they’ve been in touch with planners of the Presidio Tunnel Tops and that “there are a lot of parallels to draw from.”
If Prop K loses, the weekend closures and weekday traffic will remain as a pilot project through December 2025, which will require another round of arguments about the fate of the Great Highway.
Sup. Engardio, who is up for reelection in 2026, has taken heat from his constituents who hate the closure idea. But he thinks they’ll come around: “We can still get cars where they need to go and have an amazing park.”
Prop K is a misguided ballot initiative that Supervisor Engardio and some of his cronies in City Hall snuck in at the last minute, to the dismay of many throughout the City. There is no question that it will have significant negative impacts, including the release of additional of climate-warming greenhouse gasses and air pollutants; traffic jams on Chain of Lakes Drive, Lincoln Way, Sunset Blvd., and 19th Avenue; reduced access for emergency vehicles; dangerous traffic conditions for residents of nearby streets; risk of damage to the adjoining sand dunes and harm to the endangered snowy plover. And there is no assurance there will ever be enough funding for a park that could cost over half a billion dollars to construct. There is currently a pedestrian and bike path that could be widened for even more access, which would enable the roadway to be shared by everyone. Additionally, many supporters of closing the Great Highway are associated with people who would like to see high-rise development adjoining this project, and it is believed that this is the first step toward converting this part of San Francisco into the Miami Beach of San Francisco. Vote NO on Prop K, and then encourage all stakeholders to sit down and agree to a fair and equitable use of this highway. Anything less than that is unacceptable.