David Zipper Profile picture
Visiting Fellow at Harvard Kennedy School, focused on the future of cities, tech & mobility. Startup advisor/policy wonk/writer (@CityLab, @Slate, @TheAtlantic)
5 Dec
More evidence that bikeshare is transit's friend:

In Champaign-Urbana (Illinois), pedal bikeshare increased bus ridership by 1%, and then upgrading to e-bikeshare grew it 1.1% more.

doi.org/10.1016/j.tra.… Image
This study found many bikeshare trips providing first-mile/last-mile transit access. Makes sense.

Another possible synergy: Bikeshare enables more residents to go car-free or car-lite, leading to more transit use (which is my own experience in DC).
This sounds reasonable, but studies indicate that Uber/Lyft reduce transit ridership.

"For every year after ride-hailing companies enter an urban market, rail ridership can be expected to fall by 1.3%, and bus ridership by 1.7%." bloomberg.com/news/articles/…
Read 4 tweets
29 Nov
In @TheAtlantic, I argued that the USA must stop claiming that human error alone causes 94% of traffic deaths (~40k per year, and rising).

Beyond being incorrect, it’s a deeply damaging myth.

A 🧵:
Laying blame on the driver (or pedestrian or cyclist) is convenient for many powerful forces in transportation. But it’s counterproductive.

People do make mistakes that lead to crashes. But more often than not, other factors could’ve prevented or mitigated the collision.
What if the road engineer designed a less confusing intersection? What if the truck wasn’t so heavy or tall? What if the cyclist had a protected bike lane?

Focusing solely on human error ignores questions like these.

Read 17 tweets
6 Nov
The newly-passed infrastructure bill could bring major - and very positive - changes to auto safety.

Example: The bill requires that autos be equipped with tech to detect when the driver is drunk (and prevent them from driving). The alcohol industry fought this hard.

The bill also pushes USDOT to (finally!) update the New Car Assessment Program (crash test dummy program), to evaluate the risk that car models pose to pedestrians and cyclists -- who are currently completely ignored.
Minimum performance standards for Advanced Driving Assistance Systems, addressing the wide (and confusing) disparities in what these systems can do right now.
Read 10 tweets
29 Oct
The e-bikes are getting faster. Cities aren’t ready.

A 🧵 about my new article in @CityLab
This month @VanMoof unveiled the V, a “hyperbike” capable of 37 mph - faster than the fastest Tour de France time trial.

VanMoof knows that regulations aren't designed for a bike like this, but CEO Ties Carlier told me he expects governments to adapt.
In the USA, an e-bike that exceeds 28 mph falls into a regulatory limbo. State officials admitted to me that they don’t know how to treat it.

Is it a bike - or a moped, which would trigger extra rules for registration, helmet use, etc?
Read 9 tweets
28 Oct
UPDATE on the federal e-bike tax credit:

Congress' new reconciliation language DOES include the e-bike tax credit -- and it's back up to 30% of the e-bike's cost (the House had previously cut it to 15%).
Other core elements remain the same-- still means-tested (starting at $75k income), still requires the e-bike to cost less than $5k.

Look at page 1285:
Also -- and this is important -- the reconciliation language would make bike and bikeshare eligible for commuter benefits (i.e., pre-tax expenses).
Read 7 tweets
23 Oct
I’m in the Washington Post today, sharing 5 myths about highways.

Here’s a 🧵 with a quick tour:
Myth 1⃣: "Wider highways move traffic faster"

Nope! Expanded highways attract more car trips, which inevitably slows traffic down again. You can blame induced demand, a theory that economists (but not construction-loving state DOTs) have long accepted.
Myth 2⃣: "94% of human crashes are caused by human error"

Nope! Blaming the driver alone lets others off the hook, including engineers who design dangerous roads, car companies building heavier & taller SUVs/trucks, and cities underinvesting in sidewalks.
Read 7 tweets
22 Oct
In @Slate, my take on the controversy around Dr. Missy Cummings’ appointment at @NHTSAgov — and what it means for the Biden admin's ability to address the recklessness of Tesla Autopilot and Full-Self Driving.

A 🧵:
A Duke professor and human factors expert, Cummings is well qualified for the role, which requires working w/carmakers, tech co's, gov officials, and advocacy groups.

A backlash has come from the company whose pattern of disregarding safety gives it the most to lose: Tesla. Image
Cummings has been vocal about the dangers of Autopilot and Full-Self Driving (I interviewed her for this piece last December).

But that doesn't mean she's biased -- it makes her realistic and knowledgable, like Lina Khan criticizing Facebook.
Read 10 tweets
12 Oct
Are autonomous vehicles just a tech-y way to codify the car’s dominance of American cities?

That’s what historian Peter Norton argues in his new book, Autonorama.

My conversation with him, in @CityLab bloomberg.com/news/articles/…
Norton claims that AVs are the latest in a long line of futuristic automotive technologies that promised to turn cities into car-centric utopias.

It never works out, but there’s always another amazing new invention to captivate us.
Meanwhile, those envisioning a tech-powered automotive nirvana are distracted from mundane (but proven) ways to improve mobility networks.

Examples: Expanding transit service, installing bike lanes, and building densely around transportation nodes.
Read 4 tweets
10 Oct
Public officials could powerfully improve urban lives by emphasizing **access** (easily reachable destinations) instead of **speed** (fast roads + rail).

A 🧵 about this new-ish book (2019), which explains why -- and how. Image
"Access" is tough to define in a tweet, so here's a useful illustration from @humantransit and his team. humantransit.org/2021/03/basics…

The concept seems intuitive, but its implications are profound. ImageImageImageImage
For instance, we shouldn't gripe about traffic congestion in a city like NYC without also acknowledging the proximity of destinations.

Slower speeds matter less if you’re only going a miles or two instead of 20 or 30. Image
Read 7 tweets
28 Sep
Economists and urban planners have known for decades that highway expansions can't solve traffic congestion.

Why, then, do so many states keep widening their roads?

A 🧵 about my deep dive in @CityLab
Economist Anthony Downs gets credit for the idea of induced demand, but its roots go back *much* further than his 1962 article.

In 1927, engineer Arthur S. Tuttle warned that new urban roads “would be filled immediately by traffic which is now repressed because of congestion.”
In the 1920s and 1930s city officials worried about wooing suburbanites to shop and work, so they shrunk their sidewalks and ripped up public space to accommodate more cars.

It was a disaster. Congestion only grew.
Read 14 tweets
7 Sep
Flashy, complicated infotainment systems are creating a growing safety risk. And it's likely to get worse.

A 🧵 about my investigation, in @Slate
Why worry about infotainment systems? They’re harmless and fun, right?

Well, not necessarily. A study by the AAA Foundation found that rerouting a destination can distract a driver for up to 40 seconds—enough time to cover half a mile at 50 mph.
Even if a driver uses voice commands, systems often require looking at a car's touchscreen (and not the road) to verify accuracy. That’s inherently risky. Image
Read 14 tweets
5 Jun
A provocative question in this book by @STS_News: Why doesn't the USA regulate car safety like emissions?

"How would automakers transform their products if we mandated that they reduce the number of automotive fatalities in new cars by, say, 40% within 10 years?"

A thread 🧵:
For a century, automobile safety has largely focused on 1) driver education and 2) voluntary agreements by automakers to build safer cars.

Both those approaches are flawed.
Here's future Sen. Daniel P. Moynihan critiquing safety education in 1959:

It "shifts public attention from factors like auto design, which we can reasonably hope to control, to factors such as the temperament and behavior of 80M drivers, who [will ignore] a bunch of slogans."
Read 8 tweets
10 Apr
Just finished @shigashide's book about how to improve bus service—it’s good!

Loads of useful info about operations as well as advocacy. And a surprisingly easy read.

Short 🧵: Image
2/ Here's an excellent rebuttal to those (like Gov Cuomo) who claim fancy stuff like USB ports and wifi will attract loads of new riders: Image
3/ @humantransit is a clear influence, so I wasn't surprised to find this stinging critique of microtransit:

“When existing bus routes are unreliable and slow, focusing attention on microtransit is like trying to perfect dessert at a restaurant that routinely burns the entrees.”
Read 5 tweets
11 Nov 20
Oversized SUVs and trucks are a growing menace to people outside of them-- including pedestrians, cyclists, and occupants of smaller cars.

A Biden admin can begin fixing this (even w/o the Senate).

Here's how. 🧵⤵️
Some context: The National Highway Traffic Safety Administration (NHTSA) evaluates the design of new autos through its influential New Car Assessment Program (NCAP)-- aka, "the one with the crash test dummies."

Automakers are eager to score valuable ⭐️⭐️⭐️⭐️⭐️ NCAP ratings.

NCAP only looks at risk to a vehicle's occupants. Pedestrians, cyclists, and those in other cars don't count.

That gives automakers little incentive to protect vulnerable street users. Instead, they're in an arms race to design the biggest, tallest SUVs and trucks.

Read 9 tweets
24 Oct 20
Fall seems to be the season for Mobility-as-a-Service panels and debates.

Speaking at several has led me to reflect on my own MaaS journey, summarized in the 🧵 below (w/article links).

TLDR: Despite great promise and hype, very few people use MaaS today. We need new models.
2/ I first learned about MaaS ~5 years ago. It offered a captivating vision: Leverage new technology to knit together trips on transit, bikeshare, carshare, scooters etc to improve cities and reduce private driving.

I was fascinated and wanted to learn more.
3/ 2 years ago I heard a top US transportation guru cite Helsinki as the future of urban mobility “because everyone there uses Whim, a MaaS app, to get around town.”

I then met several Finns who disagreed. That led to this article, my first about MaaS.
Read 10 tweets