Maybe it’s the sleekness. Or the digital disruptiveness. Or something slipped in the water bottle on your seat. Whatever it is, some data mavens are contorting into pretzels to deny the obvious — that Uber is contributing to the slowdown in Manhattan traffic.
The latest Don’t Blame Uber entry was a New Yorker post over the weekend by Ben Wellington, a Pratt statistics prof and mainstay of the “Open Data Movement” via his I Quant NY website. “Uber Isn’t Causing New York City’s Traffic Slowdown,” screamed the headline, though curiously, Wellington didn’t quite write that.
Here’s the gist of his post:
At the start of 2013, cabs were getting faster by about 0.0015 miles per hour per day. By mid-2014, they were getting slower by about 0.0013 miles per hour per day — or about one mile per hour every two years. In other words, every day, cabs were getting slower less quickly than they had the previous day, even as Uber was expanding its fleet. This is the opposite of what we would expect if for-hire vehicles were the main force behind falling traffic speeds.
Let’s unpack that.
First, mining the Taxi and Limousine Commission’s humongous database of all yellow taxicab trips from 2011 through last month — the period in which yellows have been GPS-capable — Wellington computed daily and monthly average speeds for the entire fleet (excluding ultra-long trips that might skew the averages). As the graph shows, average taxi speeds climbed from 2011 before peaking in mid-2013 and heading south. This dovetails with City Hall’s insistence that traffic in the Manhattan core has been worsening, although the drop in Wellington’s graph is less severe than the city’s figures.
So far, so good. Wellington then zeroed in on the rates of change in speeds and produced the quoted passage above. Since use of Uber really took off only around two years ago, it makes more sense to focus on the most recent 24 months. Eyeballing Wellington’s graph, average cab speeds fell an estimated 0.48 miles an hour from mid-2013 to mid-2014 and another 0.32 mph from mid-2014 to mid-2015. In effect, the decline in speeds shrank by a third. Because Uber’s presence on NYC streets has been accelerating, he reasoned, the slowdown should have been getting more pronounced, not less.
Since it didn’t, something other than Uber must have caused the slowdown.
Q.E.D.? No. For a host of reasons: