Inside the City Hall Uber Traffic Study: Where’s the Beef?

Deliberately or not, the year-to-year VMT differences are impenetrable.
Deliberately or not, the report makes it very hard to discern how the mileage of different traffic sources is changing. Graphic via

What Gertrude Stein said about Oakland is what must be said about City Hall’s new traffic study: There’s no there there.

A research effort that was going to explain how congestion in Manhattan has increased even as vehicle trips to the core have dropped has shrunk to a 12-page report bereft of conclusions supported by evidence.

It may be true, as the report claims, that increases in Uber traffic in the Central Business District (CBD) have been largely offset by decreases in trips by traditional yellow cabs, leading to little or no net traffic impact. But as best as I can tell, that assertion is based on hypothetical 2010 and 2020 traffic estimates plucked from a NYC travel model and interpolated to 2014 and 2015.

Not only is this kind of interpolation volatile and unreliable, it should have been unnecessary since yellows are fully (and competently) tracked by the Taxi and Limousine Commission while Uber was opening its books to the city’s consultant.

The question of Uber “substitution” or “additionality” vis-à-vis yellow cabs was the presumed fulcrum of the $2 million study. Ignoring the wealth of data tailor-made to answer that question, and relying on constructed numbers instead, as the study appears to have done, is dumbfounding.

The City Hall report is almost as opaque in its asserted findings of factors that have contributed to increased congestion. Here’s a rundown:

  • “Construction permits in the CBD are up 6-7 percent since 2009.” That’s a surprisingly modest increase, given that 2009 was the bottom year of the Great Recession. Even so, with no physical representation of the increase (e.g., lane-miles removed from service), there’s no way to use the figure to gauge the traffic impact of the construction boom.
  • “Pedestrian counts in the CBD are also up 18-24 percent since 2009.” That’s heartening. But the report doesn’t say if the increase was measured throughout the CBD or just in a few hot spots like Times Square. And surely DOT or its consultant have a model to tell whether such an increase would slow motor traffic a lot or a little… don’t they?
  • The report also points to an unspecified “growth in the number of deliveries,” meaning more truck traffic, which DOT could easily track. But no numbers are given, and the VMT (vehicle miles traveled) bar graph in the report (page 5), while maddeningly hard to read, doesn’t suggest a sizeable increase in trucks.

One further problem: The VMT graph suggests that yellow cabs still accounted for as much as 85 percent of for-hire vehicle traffic in the CBD last year, meaning only 15 percent for Ubers and other “e-dispatch” cars. But last summer the data jockeys at the New York Times Upshot desk concluded that Uber’s market share was already up to 25 percent. The 10-point discrepancy is troubling, both because minor increments in vehicles can touch off big drops in CBD traffic speeds, and because it reinforces the inference that the report relied on theoretical instead of actual vehicle counts.

Parsing the decline in Manhattan travel isn’t simple, as I know from trying it last summer. I think my effort was a good first cut, though I’m chagrined I overlooked increased construction as a possible factor.

But the City Hall report reads like the work of people who were only half-trying. Traffic is a serious business. New Yorkers deserve better.

  • Morris Zapp

    Well what did you expect for $2 million?

  • It takes $2 million to interpolate estimated figures? I’m in the wrong line of work!

  • Jane
  • chekpeds

    18 to 24 % increase in pedestrian volume is the most significant number in the study, still no one is discussing pedestrian congestion or the need to increase sidewalk space!

    In fact the report blames pedestrians for slowing down cars at intersections.

    And still engineers do not get that split phases signals would alleviate this problem..

  • Mathew Smithburger

    So we the taxpayers of the City of New YOrk handed McKinsey $2 million and it took them roughly six months to do this “study”. Who is a better client for McKinsey NYC or Uber? Is this or was this a real study? Why the fuck couldn’t the City of New York with its vast resources (like say the kids at Stuyvesant High School combined with TLC and DOT and Uber data obtained by subpoena) do this in say three weeks for maybe $10,000? Lot of questions. No answers. No actually here is the answer, in my opinion, De Blasio is either a crook or stupid or both. His aids are either stupid, crooks or both. McKinsey cares more about Uber than anything in this world because of Uber, Unicorns and Goldman. So really we are stupid for acting all upset and surprised. Vote these idiots out, use FOIL to get ALL correspondence between Uber, NYC and McKinsey and have someone at the New York State or Federal Level review this shit….and in the meantime encourage our City Council to restrict Uber traffic until this is all cleared up. By the way this is how you wake up one morning drinking lead for drinking water like you might find in Flint.

  • neroden

    Could McKinsey be denied their pay on the grounds that they *didn’t actually do the work*?

  • It sounds like the premise of the work was to do a flimsy job in the first place.

    I know people want to attack the mayor or demonize “consultants”… but the common thread in all these cases is a DOT that still has some major institutional issues with collecting and providing data, as well as presenting workable and convincing proposals to the general public. They continue to be extremely clumsy with JSK-era initiatives. Reforming a dysfunctional department seems to be well out of de Blasio’s wheelhouse, unfortunately 🙁

  • Jeremy Topaz

    Sounds like you are either a traffic engineer or took a course in it. Great points.

  • chekpeds

    I am not.. it is not rocket science, just common sense…
    Thanks…although some days being called traffic engineers could be construed as a critique :)))))


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