Since September, commuters using Shanghai’s Number 9 bus route have had a new way of catching a ride. Rather than stand at a designated stop, they open a smartphone app and book a ride to wherever they're going. The service, provided by Alibaba, takes those reservations into account and calculates where the bus should go, using the company’s artificial intelligence to customize the route. The idea is to boost ridership—and curb traffic—by making public transit more convenient.

Shanghai is just the latest city to give this sort of scheme a try. From Helsinki, Finland, to Sydney, cities around the world have spent the past few years trying to implement AI-fueled, on-demand bus services. Few have succeeded.

Earlier this year, Singapore decided against renewing a pilot for on-demand buses. In Germany, microtransit company CleverShuttle—which bills itself as more of a ride-pooling service than a bus—pulled out of three of the eight cities it was operating in, citing economic and bureaucratic hurdles. In a pilot project with shared rides company Via, bringing underserved residents to public transit nodes, Los Angeles Metro is spending $14.50 per trip—twice what it spends on a regular bus trip.

On-demand buses have been a thing for decades. Public transit agencies often call them demand-responsive buses, and deploy them to serve users who lack easy access to standard routes because they live especially far away, or may have special needs. Because they reach relatively few people, they’re expensive to operate. They’re inefficient too, often making riders wait undetermined amounts of time for a ride. So cities must strike a balance between making public transit accessible to the largest number of residents, and meeting their budget goals.

“Elite projection: the mistake of not realizing that you are in the minority by virtue of being elite, which means that you may be in love with something that doesn't actually scale to the whole population.” Jarrett Walker, public transit consultant

Projects like the one in Shanghai represent a new kind of effort. The new, tech-powered services—sometimes called microtransit, because they use small vehicles—claim to make those routes cost-effective and attractive by pairing transit data with the convenience of a smartphone app. The goal is to help transit agencies reach currently underserved populations, such as people who need a ride home from the train station, night riders, or urbanites who’d like to ditch the car but don’t want to use public transit.

According to the tech companies pushing this solution, making on-demand busing work is a matter of crunching vast amounts of transit data, now made available by location tracking, and using algorithms to create custom shared routes. Data will help agencies reroute buses in real time based on factors like user demand and congestion, says Amos Haggiag, CEO of Optibus, whose software helps cities plan and manage bus routes, both on-demand and fixed. “I do see mass transit, even the large buses, as much more dynamic.” Many of those companies, including Uber, think all buses, not just those in low-ridership areas, should run on demand.

Reality, though, adds complications. Not everyone who needs to get around has access to an app. Smartphone ownership remains vastly unequal among countries, and between income and age groups. The cost of data is still cited as a major barrier to smartphone use around the world. And even those who do have phones may not want to rely on them to get to work. When I point out that my smartphone shuts down when the weather gets too cold in winter, Haggiag says my situation is “extreme.” I live in Montreal, along with 1.75 million other people.

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Tech companies and planners often make decisions without considering the needs of people who are not like them. A pilot project in St. Petersburg, Florida, that let residents use Uber to connect to bus stops faced low adoption rates. The local transit authority realized residents, many of whom were low-income, didn’t know how to use Uber. They needed help on how to use the app, a planner told WIRED in 2017. Elsewhere, “smart city” initiatives have been called out for their lack of inclusivity.

The problem is “elite projection,” according to public transit consultant Jarrett Walker—“the mistake of not realizing that you are in the minority by virtue of being elite, which means that you may be in love with something that doesn't actually scale to the whole population.” That helps explain why Uber, which has undoubtedly improved the quality of life for those who can afford it, is used by many microtransit companies as a baseline for what a transit experience should look like: available on demand and ultra-convenient. “All of these companies have enormous amounts of venture capital, and therefore an enormous ability to shape the conversation in a way that serves their interests,” Walker says.