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The Secret Life of Curbs: How Cities Are Planning the Next Stage in the Streetside Revolution

An obscure municipal ordinance, issued in London in 1766, called for the first raised footways alongside city streets. Part of the Paving and Lighting Act, the edict drew a line between where carriages could legally travel and where people could safely walk and conduct business. A decade later, America declared its independence from England. But unlike our loyalty to the Crown, that urban innovation—the common curb—lives on centuries later. And its role has changed even more dramatically over the past 12 months, with COVID-19 forcing cities to reimagine the ever-evolving zone between sidewalk and street. 

For urban planners, the curb’s primary purpose is practical: to separate the realm of wheeled vehicles from that of human beings. But the car’s dominance in the 20th century altered the curb’s core function: It became, by and large, a place to park vehicles. “Today, we have about seven parking spaces for every vehicle in the United States,” says Sam Abuelsamid, a mobility analyst at Guidehouse Insights. “And up to 30 percent of the landmass in many city centers is dedicated to storing cars that are not doing anything.”

But the parking paradigm is rapidly shifting. A trendline that began with the explosion of ride hailing and ecommerce-driven goods delivery has been accelerated by the pandemic, and the emergence of self-driving vehicles will only solidify this trend. In cities around the United States, the curb is now an intermittent place for life, culture, and activity—basically anything but parking. Those fairy-light-illuminated, Astroturf-lined spaces known as parklets are not going away—even when the virus eventually recedes. 

“We have an opportunity to think about solutions and implement them before they arrive.”

Cities are being challenged to make space for emerging technologies, including shared scooter and cycling racks, curbside retail zones, and speedy pickup and drop-off areas for local eateries. “We went into a quarantine lockdown at the end of February and quickly installed hundreds of A-frame easels for priority pickups at restaurants and retail,” says Mary Catherine Snyder, a parking strategist for the Seattle Department of Transportation (SDOT), who also leads policy discussions for SDOT’s Curbside Management Team. Her team dubbed these reallocated areas “food-priority zones.”

Seattle isn’t new to the idea of innovating around curbs; the city has been digitizing its curb-based parking areas for the past two decades. “We document every linear foot for what the curb regulation is,” says Snyder. “We push that data out through the city of Seattle’s Open Data program.” This allows individuals and delivery companies to confirm that a stretch of curb is a legal parking spot. They can also pay the parking fee from the app. 

What is new in Seattle, and in other major metropolitan areas, is the transition away from curbs as places to park to reimagined places for commerce, creativity, and entrepreneurialism. “We’re focusing more on providing access to buildings, and less towards street parking,” said Snyder. “COVID highlighted the real needs of businesses, particularly restaurants, for pickup and delivery—and the role that curb space plays in that.”

Slicing and Dicing the Curb

Municipalities often get a bad rap for moving at a snail’s pace, but COVID has illustrated how fast city streets can be adapted when required. “Cities globally have suddenly and massively reallocated street space in business districts,” says Jascha Franklin-Hodge, executive director of the Open Mobility Foundation (OMF), which creates open-source data specifications and tools for new mobility technologies.

Formerly the chief information officer for the city of Boston, Franklin-Hodge anticipates that the pace of curbside change will intensify, even after COVID dissipates. “We’re on the cusp of autonomy moving from the lab to the street. And that raises a whole set of questions about the right allocation of the curb to allow vehicles to deliver people and goods to and from the curb.” 

To that end, the OMF established a dedicated Curb Management Working Group in November, taking curb digitization efforts like Seattle’s to the next level by creating standard APIs and data specifications for cities to use. Franklin-Hodge rattles off a quick list of all the things they’re accounting for: the geographical location of the curb; its length; the location of signs, parking meters, and objects like fire hydrants; the color of painted sections. “It’s literally a digital version of the physical assets on the street,” he says. “It’s about knowing that there’s a pole, its height and when it was installed—as well as the signs that are on the pole, and their level of reflectivity. Knowing that a sign was installed in 1982 could tell if anybody can read it anymore.” 

This digitization push is just one way that urban engineers are preparing for a future when parking-only zones—and the privately-owned vehicles that fill them—will gradually, over many years, begin to wane. “Nobody anticipated Bird and Lime and their scooters,” says Guidehouse’s Sam Abuelsamid. “The rollout of autonomous vehicles is going to be much slower. We know they’re coming, so we have an opportunity to think about solutions and implement them before they arrive in any significant volumes.”

Some cities are also reconsidering pricing for the use of curb space. Whether you’re parking or doing a drop-off, whether you have a resident permit or if you’re visiting, whether you’re driving a delivery truck, a ride-hail vehicle, or a private automobile—all would be charged and treated differently. This is an extension of the already common practice of dynamic pricing, in which cities charge different amounts for metered parking depending on the time of day or demand. With dynamic curb-use policies, every stretch of curb becomes akin to the drop-off zone at an airport terminal, but with digital rules enforcing desired behaviors rather than a cop telling you to keep moving. In this way, the new digital curb transforms pickup and drop-off into a fully-realized marketplace.

The Future of Pay to Play

Tim Papandreou views the emergence of a robust system for curb payments as downright existential for cities. Formerly the chief innovation officer at San Francisco Municipal Transportation Agency, he is the founder of Emerging Transport Advisors, an independent consultancy. “When it comes to public infrastructure, we are currently funded by a manually operated, fossil fuel-powered, individual ownership system,” said Papandreou. “And that’s going to collapse.”

Papandreou’s vision of the future may sound extreme, but his concerns about the domino effects of automated electric shared mobility aren’t his alone. In the world he foresees, transit infrastructure will no longer be funded by gas taxes, parking tickets, and conventional transit fares. In this new curb-based mobility world, Papandreou believes, “everything is a pickup and a drop-off, regardless of the size of the vehicle, the type, and the passenger.”

Those fairy-light-illuminated, Astroturf-lined spaces known as parklets are not going away—even when the virus eventually recedes.

Abuelsamid draws a parallel with airport landing fees. “Airlines pay a landing fee every time their planes take off or land,” he said. “Mobility service providers and delivery companies will do the same thing for curbs,” said Abuelsamid.

This brave new world of curb management might sound futuristic, but to Shenglong Gao, a product manager at Argo AI, it’s real and immediate. He helps manage a fleet of Argo self-driving test vehicles that are piloting mobility services in downtown Miami. Gao sees pickups and drop-offs as part of the continuum of challenges facing autonomous vehicles operating in cities. “There are only two parts of a journey. There’s the driving. And there’s the pickup and drop off. I think they’re both equally hard, yet equally solvable.”

The first level is routing to an address. Human drivers do something similar every time we use a navigation app. But where things get tricky is the second level: determining where to park. Current navigation apps don’t help with that. “Let’s say you’re in downtown Miami. You need to deliver a package to a certain address, so this is where you’re supposed to park,” he says, pointing to a spot on a map. “But when you arrive, there’s no open curb space because there are cars parallel parked without a gap. What do you do?”

He runs through the options. You could send the self-driving vehicle around the corner to look for an open spot there. You could have the vehicle linger and block the lane. Human drivers might be willing to bend the rules and face down honking cars, but an autonomous vehicle shouldn’t do that. The parking dilemma becomes even more complicated when there are multiple deliveries on a single block, especially when drop-offs are on opposite sides of the street.

Then there’s the execution of the parking maneuver. Gao describes an uneven regulatory environment, with federal, state, and city codes each indicating different prescribed distances from the curb for different circumstances. “For example, Pennsylvania says you should get within 12 inches of the curb, but the city of Pittsburgh requires six inches from the curb,” he says. “And what if there’s an object in the way?”

As a self-driving system figures this all out, the ride hailing passenger or the recipient of a delivery needs to be notified of the exact location and timing of the scheduled pickup or drop-off. The logistical issues soon become as complex as the technological ones. 

Gao is undaunted by these challenges—and he points to the Argo self-driving system’s sophisticated technology and reasoning ability as keys to unlocking the puzzle. He can already envision the emergence of a shared vision between cities, mobility providers, and self-driving technology companies. “I totally see it working,” he said.

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