Taxi-sharing could decrease pollution, traffic, fares (and more)

A whopping 70 percent of New York City taxi rides are shareable, according to a recent study reported by Salon. (True shareability means when New York cab riders are willing to share a car with one other rider, and manage at most an extra 150 seconds of travel time.) The benefits are startling: taxi travel time would be reduced by 25 percent, and the total distance traveled by New York cabs would drop by 40 percent, resulting in reduced air pollution and speedier travels for other vehicles on the streets.

Is a 40 percent drop in total distance traveled all that significant? Well, New York has around 13,500 registered taxis; these are almost always in use, and comprise a large percentage of traffic in Manhattan, which itself sees 400,000 rides in and out daily. Salon puts the potential impact into stark relief: Recall earlier this year, when the city of Paris required alternate driving days, with odd- and even-numbered license plates rotating. Traffic dropped by a mere 20 percent in that case.

The study, out of the Massachusetts Institute of Technology, developed a “shareability” algorithm to analyze a year’s worth of New York City taxi ride data. The study found that the typical taxi ride could be shared with “any of a hundred other riders.” The study was based on a fascinating experiment from 2011, when researchers collected data on the 150 million cab trips that started or ended in Manhattan, tracking the location and time of each drop-off and pickup. (Check out the data in this interesting chart, here.)

Shareability is impacted by a few factors: how much time a passenger is willing to add to her trip, how much time transpires until a taxi won’t take on any more pickups, and how many people can share a single cab, to name a few. Researchers took all of these into account, finding that, for example, if passengers agreed to add up to an extra five minutes to their trips, around 90 percent of New York taxi rides could be shared. Then there’s another pivotal study discovery, Salon explains: “Even with 100,000 trips per day — a quarter of New York’s taxi traffic — the city would reach ‘saturation,’ or ‘near-max shareability.’ In principle, that means that cities much smaller than New York would be able to derive similar benefits from legalizing and facilitating taxi-sharing.”

What about ride-sharing services, like Uber and Lyft? While these function like taxi-sharing in that they make use of otherwise unoccupied space, Uber and Lyft are helping the taxi business grow, by putting more drivers and their vehicles on the streets. “Riders aren’t being shared; they’re being sold,” explains Salon of the system. Taxi-sharing, however, would reduce the amount of funds spent on taxis, reducing demand for so many cabs… and in doing so, reduce the number of taxis on the road by several thousand, according to study estimates.

The benefits for pedestrians, bikers, other drivers, and the environment is obvious. Though the taxicab industry would likely rebel, notes Salon, car reliance on the whole is on the decline as companies from Zipcar to the plethora of ride-sharing apps steadily render car ownership a thing of the past.