There’s a Better Way to Assess the Effect of Traffic Enforcement Than Counting Tickets

Simply tallying up summonses doesn't say anything about driver behavior, but data from cell phones could provide answers.

Mayor Bill de Blasio and Police Commissioner James O'Neill announcing Vision Zero enforcement efforts last fall. Photo: Ed Reed/Mayoral Photography Office
Mayor Bill de Blasio and Police Commissioner James O'Neill announcing Vision Zero enforcement efforts last fall. Photo: Ed Reed/Mayoral Photography Office

NYPD has increased tickets for speeding and texting while driving 50 percent so far in 2017 compared to the same period last year, Commissioner James O’Neill testified at a City Council budget hearing last week. Speeding and distracted driving are two of the most common factors in fatal and injurious crashes in NYC, so it stands to reason that this shift in enforcement is reducing the incidence of dangerous driving. But there’s no way to actually tell if those summonses are changing driver behavior.

While traffic fatalities continue to decline in NYC, the effect is most clearly understood in terms of DOT’s engineering changes and automated speed cameras. The locations of these interventions are publicly known, which makes before-and-after analysis a relatively straightforward matter. There is no equivalent technique to assess the relationship between street safety outcomes and NYPD enforcement efforts.

At the hearing, Council Member Brad Lander told O’Neill he wants to see more from NYPD about how its education and enforcement campaigns affect driver behavior. “It is good to put up billboards, and it is good to increase enforcement of offenses that lead to people getting killed and injured, but we also need to take an approach that uses that enforcement to help people change their behavior,” he said. “What I don’t think we’re yet doing is using that very expansive enforcement program to think about consequences in a way that will help drive behavior change.”

Even with precise geographic information about traffic summonses, crash data alone don’t provide sufficient detail about behavior change. You can’t tell whether the incidence of speeding, red-light-running, or distracted driving changes in response to enforcement. That’s where data collected by the company Zendrive could come in handy.

Zendrive collects information on driving behavior from anonymized data generated through people’s mobile devices. Phones enabled with the company’s technology can relay data not only about when drivers are looking at their phones, but also how fast they’re driving at any given moment, or if they make hard turns at intersections. Zendrive collects data from tens of millions of trips in New York City each month.

“The police department is out and they’re reporting on the number of tickets they’re issuing, but that’s only one data point — and it’s an input,” said Zendrive’s Noah Budnick. “The data that we have could help measure impact in real-time.”

Data from Zendrive can map the incidence of dangerous behaviors like speeding and distracted driving -- and track how they change over time. Map: Zendrive
Data from Zendrive can map the incidence of dangerous behaviors like speeding and distracted driving — and track how they change over time. Map: Zendrive

Researchers at NYU’s Tandon School of Engineering recently produced a report using Zendrive data to map the prevalence of dangerous driving behaviors — phone use, fast acceleration, and hard braking — on NYC streets [PDF]. The same basic technique could assess whether NYPD traffic enforcement is changing how people drive.

Without this type of detailed information on driver behavior, the impact of NYPD traffic enforcement is anyone’s guess.

  • Larry Littlefield

    So there is more dangerous behavior in the densest, most pedestrian rich areas? That doesn’t correspond with my experience. Brooklyn on a weekday is pretty bad, and Queens is scary all the time — even if you are driving your car. And the evidence implies there is much more speeding and drunk driving overnight, when fewer other vehicles are in the way.

  • Kevin Love

    Don’t we just love the victim-blaming sign in front of Bill de Blasio. “Your choices matter.”

    No, Mr. Mayor. It is your choices that matter, not us. You and your administration control the street environment which is the source of the danger.

    By the way, that “us” includes a lot of children who live in NYC. Should a eight-year-old child’s choices matter?

  • com63

    This map seems backwards. The areas in red are heavily trafficked most of the time. I wonder if the app flags the normal accelerations and breaking of Manhattan driving as dangerous. The real danger is failure to yield in these areas and I can’t imagine how that is reflected by accelerations or speeding.

  • walks bikes drives

    Have to disagree with you here. Most of the advertising I have seen from DOT, primarily advertisements on the sides/back of buses use this tag line and are focused on the driving behavior. Saying your choices matter focuses on all choices, both the victim and the perpetrator.

  • AMH

    I’m not sure how the Bronx and Staten Island come out looking so good either. I do note that Manhattan/Brooklyn/Queens hotspots are around bridges and tunnels, which tend to be both pedestrian-heavy and full of aggressive drivers.

  • Jesse

    I notice the same thing other people are commenting on: that the map indicates more danger where traffic is denser and thus moving more slowly. I also notice that the caption mentions “incidence” of dangerous behavior rather than “frequency”. Does this mean that it’s mapping a total of the number of incidents of dangerous driver behavior rather than a per-driver average (i.e., this is essentially a congestion map) ?

  • Most are familiar with accidents/crashes that occur with teens and their driving. However, there is also an issue with company/fleet vehicles. These vehicles spend more time on the road than personal vehicles. Because the driver is on the clock and working, they will try to “multi-task” and do work other than driving when they are behind the wheel. Emails, phone calls, using apps and texting are often part of a drivers’ workload.

    While many states and legislators are seeking to lower distracted driving by increasing penalties, fees and regulations, there is another option. AT&T “It Can Wait” campaign is an advocacy effort to diminish distracted driving. They have an anti-texting app to be downloaded onto your smartphones. The app is called AT&T DriveMode. They make it available to all drivers for FREE!

    One area that is rarely discussed is that New York has hundreds of State vehicles that inspectors, regulators and the agricultural department use as fleet vehicles, but they do not have the technology to diminish distracted driving. I would love to see New York lead by example and use a program, like FleetMode, to block texts, redirect incoming phone calls, and impede all other apps in the State vehicles. If we want our state roads to be safer, let’s start by making our state vehicles safer.


NYPD Conspicuously Absent From City Council Vision Zero Hearing

How seriously does Police Commissioner Bill Bratton take Vision Zero? The City Council transportation committee held a hearing today to gauge the city’s progress in reducing traffic injuries and deaths, and NYPD didn’t send a single person to provide testimony or answer questions. In NYPD’s absence, Transportation Commissioner Polly Trottenberg — as she often does — had to field council […]

TA Vision Zero Report: NYPD Traffic Enforcement Up, But Wildly Uneven

NYPD increased enforcement of dangerous traffic violations during the first six months of the city’s Vision Zero initiative, but enforcement varied drastically from precinct to precinct, with some issuing fewer summonses than last year. In “Report Card: Six Months of Vision Zero Traffic Enforcement” [PDF], Transportation Alternatives analyzed NYPD summons data from January through June. TA […]

Bratton Resigns. Will James O’Neill Do Better on Street Safety?

Police Commissioner Bill Bratton announced today that he will leave NYPD next month, after a little more than two and a half years as police chief under Mayor de Blasio. He will be succeeded by James O’Neill, a career officer who currently serves as chief of department, the senior uniformed position within NYPD. On traffic safety, Bratton will […]