David Van Horn
@lambda-calcul.us
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Prof at UMD CS.
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David Van Horn
Rebecca Fachner
8 days ago
As we, the good people of America, remember J6 with horror and sadness, spare a thought for the residents of the city it happened in. DC is often overlooked as a place where folks live, but this trauma happened to us, on our streets, in the place we call home.
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Ben Ross
9 days ago
The outcome of New York's congestion pricing. All the good things that were predicted. And a very telling good thing that wasn't predicted.
www.nytimes.com/interactive/...
Models predicted that traffic would get worse outside the zone. It got better. More evidence the models are just plain wrong.
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Congestion pricing after one year: How life has changed. (Gift Article)
How life has changed in the New York area, according to data on traffic, transit and the responses of 600 readers.
https://www.nytimes.com/interactive/2026/01/05/upshot/congestion-pricing-one-year.html?unlocked_article_code=1.CFA.fU6c.kxkJHilrg8Y3&smid=url-share
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David Van Horn
David Zipper
9 days ago
Note that congestion pricing has reduced serious crashes while speeding up traffic. Normally there is a tradeoff. But congestion pricing lets cities have their cake and eat it too.
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David Van Horn
David Zipper
9 days ago
Congestion pricing is a heckuva street safety strategy
www.nytimes.com/interactive/...
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David Van Horn
WABA Cargo Bike Library
11 days ago
Congratulations to Paula from NE DC - our very first official borrower! Over the next 5 days, she plans to bike her 4-year-old to preschool and neighborhood adventures. We're so excited for them both!
#bikedc
#cargobike
@waba.org
Request to borrow a cargo bike:
forms.gle/on4yFSwVYgBu...
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13 days ago
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David Van Horn
David Zipper
14 days ago
E-cargo bikes sound pretty amazing in this new UK study: "Parents’ and children’s enjoyment, curiosity, and sense of adventure encouraged additional travel, transforming routine journeys into playful and memorable family experiences."
doi.org/10.1016/j.tb...
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David Van Horn
John Skiles Skinner
15 days ago
Here's a tragedy of DOGE that most people will never know about, even though it has big consequences: no one is left to coordinate the transition to memory safe systems code. 🧵
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David Van Horn
jennifer uncoolidge
18 days ago
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David Van Horn
AAUP
18 days ago
This year, the AAUP proved something powerful: When we fight, we win. Your gift to the AAUP Foundation will power legal challenges, advocacy & education that defend the core values of higher ed. Please donate at the link below. An injury to one is an injury to all. Together, we are stronger.
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Giving
Information about various ways to give to the AAUP Foundation.
https://www.aaupfoundation.org/giving
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David Van Horn
Mark D. Levine
22 days ago
Year 1 data on congestion pricing in Manhattan… * Vehicle traffic: -11% * Foot traffic: +3.4% * Storefront vacancy: -0.9% * Pollution: -22% * Revenue for mass transit: $548M So YES this has been a huge success.
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J. I. Swiderski, MURP
23 days ago
May is a long way away, but—ask any
#DCPol
candidate—it'll be here before you know it. Registration submitted for
#BikeDC
#RideOfSilence
2026. Mark your calendars for May 20 and plan to take a moment out of
#BikeMonth
to honor those who are no longer with us & stand for safer roads for all.
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::Ride of Silence:: Home - '0 words spoken - A million
https://www.rideofsilence.org/main.php
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David Van Horn
WABA Cargo Bike Library
25 days ago
What can I borrow from the Cargo Bike Library? 🔥Radio Flyer Via Pro 🔥Cannondale Cargowagen Neo 🔥Bunch Bike Original/K9 🔥Xtracycle Hopper ⚡Aventon TBD ⚡Tern TBD Borrow for 5 days - free!
#bikedc
#cargobike
#familybike
Sign up:
www.waba.org/library
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David Van Horn
TranspoBINGO
28 days ago
Save the date! TranspoBINGO 2026 runs Feb 5-12.🚍🚲 This year's theme: Play Your Way Through the City—where curiosity sets the route, exploration earns the points, and the city itself becomes the game.🎲 A joyful reminder of what’s possible when we move through our city together.
www.transpobingo.com
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💔
add a skeleton here at some point
about 1 month ago
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Bummed to have missed my shot meeting
@davidzipper.bsky.social
today. I just didn't know!
about 1 month ago
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David Van Horn
Terry McGlynn
about 1 month ago
You can do this right now: Think of a person who wrote a paper you love, whose work influenced or helped you, or has made your professional life better. Search up their email address. Shoot them a quick email of thanks. It means so, so much. This is a rough time of year, share some joy.
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David Van Horn
WABA Cargo Bike Library
about 1 month ago
SO much excitement for bike library launch
@ward5familybiking.bsky.social
holiday party! Yes u can borrow if.. - yr bike is in shop - cousins visiting from out of town - want to try diff type of bike - not sure biking is for you
#bikedc
borrow a cargo bike - free! Sign up:
www.waba.org/library
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Happy
@ward5familybiking.bsky.social
to all who celebrate!
about 1 month ago
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David Van Horn
jamelle
about 1 month ago
most people, left and right, treat traffic violence like the weather and not a specific policy choice
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David Van Horn
3 months ago
Computing @ Imperial are hiring four Ass. / Assoc. Profs! Priority areas: - PL - Systems - Security - Software Eng. - Computer Architecture - Theoretical Computer Science Applications from individuals from underrepresented groups especially welcome!
www.imperial.ac.uk/jobs/search-...
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Description
Please note that job descriptions are not exhaustive, and you may be asked to take on additional duties that align with the key responsibilities ment...
https://www.imperial.ac.uk/jobs/search-jobs/description/index.php?jobId=25825&jobTitle=Assistant+Professor%2FAssociate+Professor+in+Computing
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David Van Horn
David Noll
about 1 month ago
Lol at every university trustee and law firm partner who concluded they had no choice but to play ball with this bumbling fool
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Top of the list for me is her overriding MPD's Disciplinary Review Division and not firing cops convicted of murder, conspiracy, and obstruction. That's
@mayorbowser.dc.gov
's legacy too. Nobody hates us more.
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about 1 month ago
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Why is it we have to go through YEARS of fighting, planning, begging (like I did just last night at UDC) only to have
@ddotdc.bsky.social
capriciously abandon their commitments? Again and again and again, DDOT fails to deliver on its mission.
@cmlewisgeorgew4.bsky.social
add a skeleton here at some point
about 1 month ago
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David Van Horn
Alex Koma
about 1 month ago
The
@janeese4dc.bsky.social
campaign tells me they actually believe they raised about $218k from about 3k donors (2,500 from DC). They believe this is the biggest single campaign finance report in DC history: For context, Bowser had about 3,800 DC donors over the life of her 2022 campaign.
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David Van Horn
David Forbes
about 1 month ago
Importantly, this wouldn't have passed without Dem support. There was enough of a split within Republican ranks that if Dems had voted against the bill it would've been doa. Giving Trump a blank check to warmonger *and* passing an anti-trans measure was a choice.
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So glad DDOT provided activities for kids at tonight's meeting. I didn't bring my kid because it's not a safe place to bike to, but I appreciate the thought.
about 1 month ago
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Easy action for a better, more livable, and environmentally responsible DC. Last day to send a letter (it's easy!).
add a skeleton here at some point
about 1 month ago
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David Van Horn
Ward 5 Family Biking
about 1 month ago
Ammmaazzzzing news & so honored to offer this sneak peak to our holiday riders 🚴🏽♂️🚲🚴🏽
add a skeleton here at some point
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David Van Horn
Kiran
about 1 month ago
Functional programming is when you write programs that are correct i.e functional
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One of the first things
@janeese4dc.bsky.social
should do as Mayor is release the *2019* congestion pricing study.
add a skeleton here at some point
about 1 month ago
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It's wild how transit inaccessible UMD remains. No direct
@wmata.com
bus line from Silver Spring or Takoma Park transit stations. I know the
@purplelinemd.bsky.social
will help with Silver Spring, but like you could also just run buses on that route *now*.
about 1 month ago
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David Van Horn
jon ben-menachem
about 1 month ago
Our new study provides rare causal evidence about NYC’s speed camera program. We find large reductions in collisions (30%) and injuries (16%) near intersections with cameras.
www.pnas.org/doi/abs/10.1...
@astagoff.bsky.social
ky.social
@brendenbeck.bsky.social
nbeck.bsky.social
🧪
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Can speed cameras make streets safer? Quasi-experimental evidence from New York City | PNAS
Each year, approximately 40,000 people die in vehicle collisions in the United States, generating $340 billion in economic costs. To make roads saf...
https://www.pnas.org/doi/abs/10.1073/pnas.2520328122
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David Van Horn
David Zipper
about 1 month ago
In the first six months of congestion pricing, air pollution within Manhattan's toll zone dropped 25%. Pollution fell across the five boroughs and in the suburbs, too. A clean air win all around.
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Congestion pricing improved air quality in NYC and suburbs | Cornell Chronicle
Cornell researchers tallied the environmental benefits of New York City’s congestion pricing program and found air pollution dropped by 22% in Manhattan, with additional declines across the city’s fiv...
https://news.cornell.edu/stories/2025/12/congestion-pricing-improved-air-quality-nyc-and-suburbs
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David Van Horn
da share z0ne
about 1 month ago
MY LEGS MY BUSINESS -
dashare.zone
ADMIN
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¡FREE CARGO BIKE LIBRARY FROM WABA! 🤯🤯🤯🤯🤯🤯🤯🤯🤯🤯🤯🤯🤯🤯🤯🤯🤯🤯🤯🤯
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about 1 month ago
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THERE
about 1 month ago
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David Van Horn
Joshua Erlich
about 1 month ago
the answer to so many questions is Unionize Your Workplace
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my bro killed it on this one.
www.youtube.com/watch?v=R7Kc...
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Zionsville ii
YouTube video by Khruangbin - Topic
https://www.youtube.com/watch?v=R7KcQe_8PoU
about 1 month ago
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David Van Horn
United Academics
about 1 month ago
Boom! We getting in the political game. Because if we don't fight in the political arena for the best interests of universities—which includes their students, faculty, & communities!—then these politicians will keep trying to take over our universities & dictate what we teach & research.
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David Van Horn
localhuman
about 1 month ago
Yeah I like waymo. Waymo public transit, bike lanes and benches!
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Good story on the success of the more dead kids movement. Sure wish the Post's "local transportation reporter" had centered the story around some place a bit more local than Los Angeles, California.
wapo.st/49WM4BI
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America’s plan to protect pedestrians failed. A young woman’s death reveals why.
U.S. officials adopted Europe's Vision Zero initiative, but many cities have seen an increase in pedestrian fatalities despite efforts to improve road safety.
https://wapo.st/49WM4BI
about 1 month ago
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David Van Horn
Goseg Train Thread
about 1 month ago
DC's lame duck mayor RUSHED to rip out popular beloved streeteries a month before the deadline and a day before emergency legislation was passed to save them. Have heard it's bc she personally hates them. Pathological how much suburbanists hate cities and what makes them popular 🚩
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David Van Horn
Corinne Low
about 1 month ago
This is a very good explanation. "I think the first strike was actually also illegal." Also "it would take them like 20 stops to refuel to make it to America" seems like an important detail to rebut the claim that these strikes are responding to any kind of "clear and present danger."
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David Van Horn
Action Committee for Transit
about 1 month ago
Sing it with us! 🎵All-day, two-way, seven-day service!🎵 🎵All-day, two-way, seven-day service!🎵 🎵All-day, two-way, seven-day service!🎵 🎵We need it on the Brunswick Line!🎵
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David Van Horn
David Zipper
about 1 month ago
Among the many reasons this is very bad: The environmental advocacy/foundation world was *just starting* to push for less driving, not just less gas-powered driving. I fear they'll now revert to promoting EVs -- full stop.
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Trump Returns to Gasoline as Fuel of Choice for Cars, Gutting Biden’s Climate Policy
https://www.nytimes.com/2025/12/03/climate/trump-fuel-economy-car-rules.html
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David Van Horn
Melissa & Chris Bruntlett
about 1 month ago
London is fast becoming a cycling city. As each new piece in the network appears—which has more than quadrupled from 90 to 431 km since 2016—so do new cyclists. Its infrastructure now sees a stunning 1.5 million daily users—a 43% spike since 2019—moving nearly half as many people as the Tube below.🧵
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projection protest in 3, 2, ....
add a skeleton here at some point
about 1 month ago
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UMD does Accessibility: There's a ridiculous, windy, long pedestrian detour that redirects a major pedestrian route *through* Iribe because of construction. Guess whether the sole ADA door works....
about 1 month ago
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