Liu’s and Pucher’s Bike-Share Math Is Wrong, and Not By a Little

Hey, remedial math teachers: the City Comptroller’s office is hiring. At least, let’s hope so. Judging from Comptroller John Liu’s innumerate broadside against the City’s Bike Share program, they badly need help in basic arithmetic, not to mention fact-checking.

Let’s begin with Liu’s own words, insinuating that bike-share might cause one or more children to die:

[T]he rush to place ten thousand bicycles on our streets … risks significantly exacerbating the number of injuries and fatalities of both bikers and pedestrians, especially those most vulnerable like young children and seniors.

This is positively bizarre. Since you must be 16 or over to be eligible to ride a Bike Share bike, Liu must be positing collisions in which a Citi Bike rider strikes and kills a child. Yet that seems extraordinarily unlikely. No New York City child has died from being struck by a bicycle in memory, or at least since 1980, when I began tracking traffic crashes here. Moreover, by design the Citi Bikes will be ridden slower than bikes now on the road, making them even less likely to be involved in serious cyclist-on-pedestrian collisions. What, then, could Liu possibly be referring to?

But the numerical piece de resistance in Liu’s press release is this quote from Rutgers Prof. John Pucher:

Safety concerns about Citi Bike stem from frequently blocked bike lanes, poor street conditions, inexperienced bicyclists, lax enforcement of traffic regulations, and the inevitability that some users will ride on sidewalks. On the basis of these traffic dangers, I would expect at least a doubling and possibly even a tripling in injuries and fatalities among cyclists and pedestrians during the first year of the Bike Share program in New York. (emphasis added)

A doubling in injuries due to bike-share? At present, on an average day approximately 650,000 bicycle trips are taken in New York City — around three each by the roughly 180,000 New Yorkers who pedal on any given day, more by bike couriers and food-delivery riders. We can expect bike-share in its first year to increase this figure by 42,000 trips. That’s based on 7,000 Citi Bikes this year, and six trips per bike per day. (London and Washington, D.C. report 4-5 rides per shared bike per day, with 6-7 in Mexico City.) Since the increase in bicycle trips from bike-share is 1 part in 15, for the program to double the daily rate of collisions, whether with cars or pedestrians, or icebergs for that matter, each Citi Bike rider would have to be 15 times more likely than a cyclist on a regular bike to crash into something or someone.

That’s a tall order. In fact, the scenario it depicts is patently absurd, even allowing for bike-share’s concentration in the heavily pedestrianized and congested Manhattan Central Business District. Why, then, is Prof. Pucher, a leading U.S. scholar on global progress in urban cycling, promoting it?

I think there are two reasons. One is that like many people who aren’t grounded in day-to-day cycling here, Prof. Pucher doesn’t grasp the true extent of NYC cycling at present. Indeed, in much of his academic work Prof. Pucher has slavishly adhered to U.S. Census “commute mode” data that ignore the multi-dimensional nature of cycling here — for errands, meetings, socializing, appointments, shopping, exercise, and just plain fun — and thus end up lowballing bicycling’s “modal share” by a factor of around four. This leads him to ascribe to bike-share an outsized increase in cycling and, hence, an outsized increase in cycle crashing.

The other factor is more speculative, and here I draw on my association with Prof. Pucher since 1998, when I co-authored one of his early journal articles, contrasting the then-glacial pace of cycling improvements in U.S. cities with cycling’s high civic status in Europe. I would guess that Prof. Pucher is so appalled at the NYPD’s failure to safeguard cyclists’ legal right of way and offended by many cyclists’ defense mechanism of bending or even ignoring traffic rules altogether that he is unable to view a big new boost in cycling here in full context. And of course when he speaks to the press and electeds, the first part of his message, about protecting cyclists, is roundly ignored, while the second, warning of disaster, gets played to the hilt.

Hopefully, Prof. Pucher’s fantastically dire predictions won’t derail the bike-share rollout. And perhaps in time he’ll learn how to hone his message to the world outside academe. It’s Comptroller Liu’s office that should know better than to broadcast such patent nonsense. After all, bike-share isn’t a toxic debt instrument or a contagious disease. It’s a bold but proven program to give city dwellers another transportation option, one that is affordable, city-positive and healthful — not to mention good for the city’s bottom line.

  • Actual City Cyclist

    1. Let’s be clear: Rutgers Professor John Pucher isn’t basing this “doubling or tripling” claim on any actual research or data. He’s pulling these numbers out of his ass. Until Pucher buckles down and does the work, shows us his research and actually makes an argument based on real data from other cities that have deployed bike-share, he has zero credibility on this issue.

    2. Pucher’s opinions on NYC’s bike-share program are politically irrelevant. His claims of bike-share Armageddon certainly are almost certainly wrong and they most definitely aren’t going to stop the program from moving forward. The only thing Pucher is harming is his own credibility. 

    3. If Pucher did feel like being useful and relevant to the cause of city cycling, he could be pointing his media barbs at the NYPD and helping policy-makers understand what international policing best practices look like when it comes to keeping bicyclists and pedestrians safe in other big cities.

    Unfortunately, John Pucher seems to have decided that he’d prefer to grind some personal axe rather than participate usefully in NYC’s livable streets revolution. 

  • Anonymous

    …not to mention that AAA buffoon’s completely unsubstantiated assertion that “New York City is probably the most dangerous place in the world to ride a bicycle.”

  • Media Critic

    Pitcher has a book coming out and giving apocalyptic quotes to the media gets him ink. No one would quote him if he told the truth about bike share’s stellar safety record.

  • Lisa Sladkus

    Thanks for this informative and clear post by Charles Komanoff. I appreciate you putting this all into perspective and shedding light on this issue. 

  • DS

    John Pucher has always cried DANGER! whenever he talks about biking.  He somehow thinks he’s helping the cause of biking by scaring people away from it.  Twit.

  • Bikirl

    Thanks for this swift and logical retort to the fear mongering against Citi Bikes.

  • Ben Kintisch

    We all know that as biking goes up in NYC, our country’s biggest city, the car people get more and more worried. So, we can only expect the AAA to weigh in on the side of irrationality and fear-mongering as they protect their shrinking portion of the American transportation scene.

  • Anonymous

    I emailed Pucher a couple weeks ago asking him if he was basing his “doubling or tripling” quote on any data.  I haven’t heard from him, not that I necessarily expected to. 

  • Station44025

    Nice post. So much of the public discussion and reporting on bikes is done in the complete absence of fact or figures beyond the anecdotal. That doesn’t stop anyone from editorializing or making sweeping policy recommendations, though. Arrest them all!!

    The fear of bikeshare-bedlam just proves that the number of indigenous NYC cyclists is vastly underestimated by the casual observer, despite the amount of media blather related to cycling. This probably part of the “nobody uses the bike lanes” meme as well. (I’m posting from my car while waiting for alternate side to end, and I’ve seen 33 bikes go by in the time I’ve spend typing this

    Thanks for injecting some actual reason into the discourse. Hopefully journalists, advocates, and policy makers will pick up on it.

  • Guest

    We should point out, Komanoff uses a different metric than Pucher does for calculating the number of riders:


  • J

    Maybe Pucher’s prediction does appear to be a bit inflated, whereas Komanoff’s own “rough but reasonable” assumptions on cycling in NYC aren’t perfect either. Komanoff’s assumptions, are extrapolated from 6 entry points into and out of Manhattan, and produce significantly higher volumes than Pucher’s. This may do more to push the issue of safety under the proverbial rug, especially considering the selective nature of the dataset in which he draws his conclusions.

    What I find interesting though is that Komanoff omits where Pucher is quoted in the press release as saying, “More needs to be done to ensure the safety of both Citi Bike riders and pedestrians.” This is certainly true, and a common theme here on Streetsblog. So why not talk about that?

    Pucher’s point speaks to the fact that the issues he lists in his quote (blocked bike lanes, poor street conditions, inexperienced bicyclists, lax enforcement of traffic regulations, etc)  are real issues faced by cyclists,and that casual users of the system (the intended market for Bike Share) may not be so eager to “bend or even ignore traffic rules” as Komanoff suggests. And if they do? It may not be so pretty, which is something Komanoff doesn’t seem to want to acknowledge. To clarify his point further Pucher, states that the increases he has concerns over are during the first year, not increases for the indefinite life of the program. Through CitiBike, for the first time there will be a true count of cycling use in the city (Origins, destinations, crash reporting), so we will have to see what those numbers really tell the DOT about safety. Obviously this will only be for a segment of the cycling population, so you’re still faced with a bit of a quandary in making assumptions.

    As an ardent supporter of all things cycling and pedestrian, I also suspect that Prof. Pucher’s quote is most certainly taken out of context for the convenience of a press release that suits Comptroller Liu’s position, and further exploited for all the wrong reasons here on SB.

  • Too bad Liu doesn’t present as much data for cyclists as he does for pedestrians. While he cites a disproportionate number of children under 10 were hit by cyclists there no info as to who these cyclists might be. Were they delivery guys on ebikes riding on the sidewalk? Salmon Ninjas darting out of nowhere? Maybe they were other children, under 10, just learning how to ride. For all we know they could be playground collisions where one 6 year old, learning to ride, rammed into a sibling and knocked out a tooth. Do we know for a fact that these children were actually hit by a cyclist or only that a bicycle was, somehow, involved?

  • Anonymous

    @72d8f51ffcff8ff508a43938e2c52a00:disqus  You and I agree that estimating the amount of cycling in NYC is a “quandary” in the absence of comprehensive official counts. Your solution, I gather, is Pucher’s, which, as I pointed out, omits all but journeys to work by people who primarily bike to their jobs. For me, that approach would omit 90 of the 102 miles I biked in the city in the past week. Other riders here have similar patterns, I’m sure.

    Your harping on six entry points ignores the care I took to extrapolate conservatively. For example, my model steadily reduces the ratio of all NYC cycling trips to cordon-entry cycling trips, from 17.5 in 1990, to 15.2 in 2006 and 12.3 last year. Absent that adjustment, my imputed number of citywide trips would have been a lot greater.

    Your point about Bike Share cyclists bending traffic rules would make sense only if the existing base of cyclists didn’t already do that. But of course we do, for the reasons I stated in my post.

    An earlier Streetsblog post covered Pucher’s safety pleas; I guess  you missed that. As for Pucher’s being quoted out of context, that’s pure bunk and you know it. As the first comment here, from “Actual City Cyclist,” made clear, Pucher had no basis whatsoever for positing a doubling or tripling in bike-related crashing. And if he didn’t know that the press would flock to that like meth-heads to crystal, then he needs to turn off his phone.

  • Actual City Cyclist

    @72d8f51ffcff8ff508a43938e2c52a00:disqus Here’s what I think you fail to understand:

    The media quotes John Pucher for his academic imprimatur. As an academic, the assumption is that Professor Pucher has done peer-reviewed research to back up his claims, particularly when he cites statistics, like his prediction of a “doubling or tripling” of injuries and fatalities upon the launch of bike-share. Yet, it does not appear that Professor Pucher has done any meaningful research to back up the hysterical claims that he keeps repeating to New York City’s local media. Where’s your data, Dr. Pucher? How’d you come up with this staggeringly dire prediction that 60 cyclists will die in NYC next year instead of 20 because of bike-share? Please, do tell. Komanoff makes good points about Professor Pucher’s insistence on hewing to crappy Census data to analyze bike trips — data that we know does a horrible job of accounting for the totality of NYC bike trips. But this argument over Census data vs. screenline counts is a distraction. The bottom line is that we have not seen a big jump in injuries and fatalities happen in any other city upon the launch of bike-share. Thus, the burden is on Dr. Pucher to show why he thinks NYC’s bike-share system will be such an extreme exception and will cause a huge jump in ped/bike injuries and fatalities. The fact that he is making this claim to all kinds of local and national media without having done the reserach is simply academic malpractice on Professor John Pucher’s part. That’s the problem I have with it. Beyond that, it is also sad to see Professor Pucher — an enthusiastic, car-free, cyclist — allowing himself to be used by some of the most anti-livable streets forces in New York City to provide cover for their silly, ongoing campaign to undermine biking in NYC. Truly, I can’t imagine what’s going on in Pucher’s head. I imagine he sees himself exercising some sort of fearless academic independence for the good of NYC biking. In reality, he is aiding the very people who will be working their hardest come January 1, 2014, to reverse the Bloomberg/Sadik-Khan livable streets legacy. 

  • J

    @72d8f51ffcff8ff508a43938e2c52a00:disqus I agree with Komanoff.
    Pucher should know better than to feed a series of negative and positive quotes to the media and politicians with a history of anti-bike sentiment and expect balanced, nuanced reporting. Also, as an advocacy news source, it is decidedly Streetsblog’s place to respond to the negative accusations which were highlighted by the media and Liu, especially given what seems to be wild, unsupported hyperbole that does not match at all with the experience in other cities.
    In addition, as Komanoff pointed out, Streetsblog has already devoted an entire article to the positive aspects of Liu’s press release.

  • David Barouh

    An article today by Felix Salmon:

    greatly expands on the point in Charles’ article that Prof. Pucher vastly underestimates the number of NYC cyclists and Cycling trips, and that Liu is using that to vastly overestimate the lack of safety of NYC cycling. 

    He shows a chart Liu uses placing NYC as among the least safe cities in which to cycle. In that chart, titled “Average Annual Bicycle Fatalities Compared to Bicycle Commuters, 2004-2009” NYC comes out far more dangerous than eight other major North American cities. The flaw in the chart is that, as Charles shows, there is far more cycling in New York than there is bicycle commuting. The chart would have been more accurate had it compared the total number of cyclists than just bicycle commuters. Apples and oranges.  

  • fj

    Got money?

    Campaign Finance Scandal Gives City Controller John Liu Labor Pains


John Liu: Cyclists Need Helmets, But Not Bike Lanes

What does John Liu think of bikes in NYC? That’s hard to say, and it’s not clear that Liu knows either. On the day when thousands signed up for the city’s bike-share program, exceeding expectations and setting the stage for a major shift in the way many New Yorkers get around, Liu chose to engage […]

John Liu: Halting Bike Access Bill Not a Political Move

Does anyone believe that John Liu’s position on bicycle access to buildings has remained consistent since last September? We’ve got an update about the petition drive urging Council member John Liu to hold a vote on the Bicycle Access Bill in his committee: It’s got people fired up. From Crain’s Insider: A cycling advocacy group […]