David Zipper Profile picture
Sr Fellow @MIT Mobility Initiative + Contributing Writer at Vox, focused on transportation. Words in @Slate @TheAtlantic @CityLab https://t.co/QE33pKTUuw
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Mar 30 13 tweets 5 min read
Fifty years ago, William Whyte studied how New Yorkers schmoozed, sat, and relaxed the small open spaces available to them. This 1980 treasure was the result.

Join me as I share a few timeless lessons. 🧵 Image A key urbanist insight: “Supply creates demand.”

Comfortable urban spaces attract people happy to find a place to chat, eat, or read.

It's also the core idea behind induced demand, which explains why highway widening is futile (and why good bike lanes create more riders). Image
Dec 18, 2023 16 tweets 8 min read
Oversized SUVs and trucks kill people in crashes, catalyze climate change, and widen inequality. And the problem is getting worse.

A 🧵 about my deep dive on car bloat, in @Slate Image @Slate “Car bloat” describes the shift in new car sales toward increasingly massive SUVs and trucks.

In 1977, SUVs and trucks comprised 23% of US car sales. Now they are over 80% -- and individual models keep adding weight and height. Image
Nov 19, 2023 9 tweets 5 min read
Today is World Day of Remembrance for Road Traffic Victims. #WDoR2023

Notably, Americans are 2-5x more likely to die in a crash than those in peer nations. And the gap is widening.

Here are a few often overlooked ways to reduce the carnage. 🧵

Image 1) Invest in mass transit

Buses and trains are 30-66x safer per passenger mile than driving.

Places with strong transit systems have more transit trips and less driving. They therefore have fewer crash deaths.

Nov 18, 2023 11 tweets 6 min read
Last week the National Transportation Safety Board recommended that speed-limiting technology be required on all new cars.

It’s an excellent idea. @USDOT should do it.

My latest in @FastCompany. 🧵 below

Image Consider this horrific crash last year in North Las Vegas.

A man on cocaine and PCP drove his Challenger at 103 mph through a red light, smashed into a van, and killed himself and eight people.

Speed-regulating tech could’ve prevented it.

Nov 12, 2023 7 tweets 4 min read
This is the best series on road safety I’ve ever seen.

Last week @nbcdfw ran a multi-part investigation into Dallas' epidemic of car crashes.

Rather than blame drivers, the story delves into speed, street design, and Vision Zero's failures.


nbcdfw.com/investigations… Context: It’s hard to overstate how terrible Dallas is at road safety.

The city has more deaths per capita than any US city of >1M. Many of the most deadly roads are managed by TxDOT, outside the city's reach. Image
Nov 9, 2023 7 tweets 4 min read
For the first time, the EPA is investigating the environmental harm caused by tires.

The federal government is finally acknowledging that tailpipe emissions are just one of the ways that cars befoul the planet.

Me in @Slate. 🧵 below

Image The chemical in question, 6PPD, makes tires more durable. It turns into 6PPD-quinone when exposed to air.

In 2020 @UW researchers published a bombshell study blaming 6PPD-quinone for the collapse of coho salmon in the Puget Sound.

Sep 13, 2023 9 tweets 4 min read
I visited Pontevedra, a Spanish town whose motto is “fewer cars, more city.”

In 24 years, traffic fell 97% in the historic center and 53% citywide. And Pontevedra is flourishing.

In @FastCompany, here are 5 lessons from Spain’s car-free pioneer. 🧵
fastcompany.com/90952175/this-… @FastCompany When Pontevedra Mayor @Lorespontevedra was first elected in 1999, the city was in the doldrums.

Its economy was sputtering and younger residents were leaving.

The new mayor thought he had a solution: Get rid of the cars. Image
Aug 28, 2023 15 tweets 6 min read
What happens when an entire town putters around on golf carts?

To find out, I visited Peachtree City, GA, an Atlanta suburb where most families own one.

TLDR: It’s pretty awesome.

A 🧵 about my deep dive in @business/@CityLab

bloomberg.com/features/2023-… Peachtree City was planned in the 1950s in then-rural Fayette Co. Its design drew from New Towns that emphasized green space & a cohesive urban plan.

Peachtree City would have streets and roads, but also a network of car-free paths.

Aug 6, 2023 4 tweets 2 min read
Welp, it seems I'm not the only one who sees car bloat as a major problem -- one that we ignore at our own peril.

This thread received more comments than anything else I've tweeted, by a wide margin. Most were positive. (cont'd) There was some interesting pushback. (I'm ignoring meltdowns from the jabronis w/huge trucks and thin skins)

Here's Ford's comms lead, trying to deflect. I don't blame him -- Ford doesn't offer any sedans in the US; its profits depend on big SUVs/trucks.
Aug 5, 2023 11 tweets 5 min read
I’ve spent much of this year learning about car bloat, the process through which smaller vehicles are being replaced by increasingly massive SUVs and trucks.

What I’ve learned: Huge cars are terrible for society, often in ways that are hidden.

A summary 🧵 Image First, some basic info:

🔹 >80% of US car sales are now trucks/SUVs. Europe is behind, but catching up.
🔹 Models keep expanding. Ex: The 2023 F-150 is ~800 lbs heavier and 7 in taller than in 1991.
🔹 EVs can make the problem worse due to huge batteries.
Jul 17, 2023 11 tweets 4 min read
Crashes kill 43,000 people per year in the US.

Self-driving car companies claim to have the solution.

I call bullshit. 🧵 below
slate.com/technology/202… To be clear, 43,000 crash deaths per year is horrific. The US has 2x to 5x more traffic fatalities per capita than other rich countries.

@SecretaryPete right to call it a “national crisis.”
Jul 9, 2023 10 tweets 4 min read
You might’ve noticed a lot of recent news about robotaxis in San Francisco.

That’s b/c California officials will soon decide whether to let Waymo/Cruise deploy unlimited AVs, something the city vehemently opposes.

Much is at stake. An explanatory🧵
washingtonpost.com/technology/202… Being the urban hub of Silicon Valley, San Francisco has been target #1 for robotaxi companies, esp Cruise and Waymo.

The city itself has no power over these vehicles on its streets; it doesn’t even receive data about how many are deployed.
Jun 22, 2023 4 tweets 2 min read
New report finds that over 8,000 pedestrians were killed on US roadways in 2022.

Jimmy Carter was president the last time that happened.

@GHSAHQ The US is terrible at roadway safety in general -- but we are truly abysmal at pedestrian safety.
Jun 20, 2023 4 tweets 2 min read
Awful to learn of this fire last night.

Not much info yet, but it's worth noting that such fires virtually always involve heavy-duty, cut-rate vehicles from abroad that are improperly serviced. E-bikes from established brands/retailers are very safe.
nytimes.com/2023/06/20/nyr… Battery fires are a serious issue, one that must be addressed. But it's a problem that involves sketchy models sometimes used by deliveristas -- not the average person.
Jun 2, 2023 7 tweets 4 min read
NEW: San Francisco officials have sent a letter to the state of California opposing Waymo’s request to operate an unlimited number of robotaxis anywhere in the city, 24/7.

The letter pulls no punches, describing myriad problems Waymo's robotaxis are already creating in SF. ImageImage SF is the canary in the coal mine, the first US city to see lots of AVs.

This is a map of instances where AVs have blocked traffic, obstructed transit, disrupted emergency response, etc.

It's likely a gross undercount, since only a fraction of such incidents are reported. Image
Jun 1, 2023 11 tweets 5 min read
Electric vehicles are getting bigger and bigger, endangering everyone walking, biking, or inside smaller cars.

Biden and @USDOT have avoided acknowledging the risks – let alone addressing them.

Me, in @TheAtlantic 🧵
theatlantic.com/ideas/archive/… The dangers of oversized SUVs/trucks are clear. Extra weight conveys more force in a crash and elongates braking distances. Added height expands blind spots.

US bike & ped deaths are at a 40-year high, and research has found larger cars partly to blame.

wthr.com/article/news/i… Image
May 16, 2023 12 tweets 7 min read
How can US cities escape the iron grip of automobiles?

Look to Brussels, which used to be a car-clogged mess. But in 5 years, cars' share of local trips fell from 64% to 49% --while walking & biking have surged.

US cities can do it too. Me in @CityLab 🧵
bloomberg.com/news/features/… It’s hard to overstate how autocentric Brussels was in the 20th century.

Highways dumped cars into the city, and companies got a tax break to buy autos for employees. Entire neighborhoods were leveled to build roads.

The iconic Grand-Place became a parking lot. Image
Mar 30, 2023 10 tweets 5 min read
Is transit a “public good,” as many fare-free advocates claim?

No, it is not.

A 🧵 about my latest in @CityLab
bloomberg.com/news/articles/… Google the phrase “transit is a public good,” and you’ll find >17k hits.

Fare-free boosters, city leaders, Congressional reps, and think tanks have treated it as a fact.

But they are mistaken.


Mar 27, 2023 12 tweets 9 min read
My first @voxdotcom story is a deep dive asking how transit can avoid a downward spiral.

1) Focus on providing quality service that competes w/cars
2) Minimize distractions (including bus electrification and going fare-free)

🧵 below
vox.com/future-perfect… @voxdotcom This is an emergency.

Federal COVID funds are dwindling, but ridership and fare revenue are way down. That leaves big transit agencies facing huge annual deficits of $100s of millions+.
Mar 22, 2023 12 tweets 5 min read
For decades, US environmental groups have pushed to make cars less polluting, rather than reduce driving.

At long last, that is starting to change.

A 🧵 about my new story in @Slate
slate.com/technology/202… An example: When the federal e-bike bill was first proposed in 2021, you could’ve counted environmental groups supporting it on one hand.

But a parade of them is endorsing the new version that was unveiled yesterday (below).

This is no accident.
Mar 21, 2023 9 tweets 6 min read
BREAKING: The federal e-bike bill is BACK.

A new proposal would give Americans up to $1,500 off a new e-bike.

This bill is similar to its predecessor, which came tantalizingly close to passing last year. BUT there are some key differences.

panetta.house.gov/media/press-re… Many of the new EBIKE Act’s core elements are the same as before:

→ E-bikes, e-cargo bikes, and e-trikes are eligible
→ Bike price capped at $8,000
→ Max credit of $1,500 or 30% of purchase price
→ Credit potentially available through retailers