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David M Levinson ⁂

@transportist.org
1.7K followers 895 following 1.3K posts

‪https://www.transportist.org @transportist@mastodon.social‬ @transportist.mastodon.social.ap.brid.gy Trnsprtst. Rogue Planner. Refreshingly Unromantic. So F*ing Lucid. fRSN. 2%. Research: #Access, #TransportEconomics, #NetworkEvolution, #Traffic.

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David M Levinson ⁂ @transportist.org · 5h
ICYMI: Chose your fatality
dlvr.it
Chose your fatality
Personal safety often gets more attention than road safety. Both are important, but I would guess people misunderestimate their relative magnitude. I looked at some data from New South Wales, which to be clear is significantly safer on both dimensions than the US. In recent years, New South Wales has recorded the following statistics: Homicides: There were 85 murders in 2024, the highest annual count since 2014. In the 12 months leading up to March 2026, there were 87 recorded murder victims. (See: On Bondi Beach) Road Deaths: * Road Fatalities: In 2025, 355 people died on NSW roads, vs 327 in 2024. Speeding was associated with 134 deaths in 2025. * Pedestrians: 54 deaths, representing a 25.6% increase from the previous year. The majority of the 54 pedestrian deaths occurred on everyday suburban streets. Older road users (aged 70+) were particularly affected, accounting for 18 of these pedestrian fatalities. * Cyclists: 15 deaths (including three e-bike riders), which was a 200% increase over the 5 fatalities recorded in 2024. Cycling has notably increased with the advent of e-bikes in recent years. These increases occurred despite (because of?) broader national efforts to improve safety for vulnerable road users. The state government simultaneously blames drivers for driving too fast while opposing safe speed policies, and opposing the use of regulatory devices like unmarked speed cameras. --- FIN Read more
011
David M Levinson ⁂ @transportist.org · 29/09/2026
Chose your fatality
dlvr.it
Chose your fatality
Personal safety often gets more attention than road safety. Both are important, but I would guess people misunderestimate their relative magnitude. I looked at some data from New South Wales, which to be clear is significantly safer on both dimensions than the US. In recent years, New South Wales has recorded the following statistics: Homicides: There were 85 murders in 2024, the highest annual count since 2014. In the 12 months leading up to March 2026, there were 87 recorded murder victims. (See: On Bondi Beach) Road Deaths: * Road Fatalities: In 2025, 355 people died on NSW roads, vs 327 in 2024. Speeding was associated with 134 deaths in 2025. * Pedestrians: 54 deaths, representing a 25.6% increase from the previous year. The majority of the 54 pedestrian deaths occurred on everyday suburban streets. Older road users (aged 70+) were particularly affected, accounting for 18 of these pedestrian fatalities. * Cyclists: 15 deaths (including three e-bike riders), which was a 200% increase over the 5 fatalities recorded in 2024. Cycling has notably increased with the advent of e-bikes in recent years. These increases occurred despite (because of?) broader national efforts to improve safety for vulnerable road users. The state government simultaneously blames drivers for driving too fast while opposing safe speed policies, and opposing the use of regulatory devices like unmarked speed cameras. --- FIN Read more
011
David M Levinson ⁂ @transportist.org · 27/09/2026
I assure you I didn't do this. LimeBikes are heavy.
pixelfed.social
David Levinson (@transportist@pixelfed.social)
#LimeBike Sculpture, #Sydney
000
Reposted by David M Levinson ⁂
Liberal Currents @liberalcurrents.com · 26/09/2026
"A future administration will have some obvious decisions to make. But if all that happens is restoring the status quo, we will have wasted an opportunity to rethink the relationship between the US government and science, one that has persisted since the post-World War 2 era."
liberalcurrents.com
Seeing Like a Gardener: A New Framework for the Public Funding of Science
Chapter 11 (pp. 84–91) from The Reconstruction Papers.
03715
David M Levinson ⁂ @transportist.org · 26/09/2026
ICYMI: Designing for Quiet
dlvr.it
Designing for Quiet
Below summarises my presentation at a Forum on Vehicle-Generated Noise Pollution at New South Wales Parliament House on September 23. For my international readers, while noise is an issue in many places, in Australia this is an issue because of the popularity of hooning, anti-social operation of vehicles, especially noisy driving (modified engines, tyre burnouts (spinning the driven wheels while holding the car still), etc.) Wikipedia reports: A hoon (/huːn/ ⓘ) is an Australian and New Zealand term describing a person who deliberately drives a vehicle in a reckless or dangerous manner, generally in order to provoke a reaction from onlookers. Decibels If a tree falls in the forest and there is no-one there to hear it, does it make a sound? Of course. But does it make a noise? No. Noise is unwanted sound. It is a negative externality; it requires both someone making the noise and someone hearing it without wanting to. What matters to the person trying to sleep is how loud each event is and how many events there are. In contrast with intuition, decibels are logarithmic. One truck may be 80 dB, but two trucks are “only” 83 dB. Ten decibels more sounds about twice as loud, so a modified motorcycle at 90 dBA is heard as sixteen times louder than a 50 dBA street. A quiet street with one loud vehicle is worse than a busy one with a steady stream of vehicles. The background is low and every pass stands out. Money We have heard from my colleague Edmund Lau at the University of Sydney about the health effects of poor sleep, resulting from noise. But everything in Australia is about real estate. Hedonic studies of real estate prices near highways and airports give us a Noise Depreciation Index. Each additional decibel lowers the price of a house by about 0.62%. People don’t want to live near highways or under flight paths, and require a lower price to do so. Roads that invite it Some roads invite anti-social driving: long straight sections with clear sightlines, capacity to spare at night, connected loops that let a driver circulate and repeat the performance. Hard reflective surfaces, façades close to the carriageway, and light background traffic amplify the noise. Re-design Design works every hour on every driver. Geometry that enforces itself changes what speed feels natural, and it narrows the whole speed distribution, including the fast tail that does the damage. Design changes may comprise various sorts of traffic calming (but not all of them), including interventions like planting trees on the side of the road, to slow traffic. Isolated humps and stop signs produce the noisiest pattern available. Brake, sprint to the next device, brake again. The braking, the suspension and the re-acceleration all make noise. Continuous low-speed geometry is quieter: close-spaced plateaus, raised intersections, and small roundabouts, along with traffic signals timed to give a green wave at the target speed rather than a clear run. Diverters cut flows and speeds together. Lower speeds also lower the level. Zurich dropped limits from 50 to 30 km/h and measured about 1.6 to 1.7 dB less at building façades, with less annoyance and less disturbed sleep reported. Re-surface Transport for NSW notes that against dense-graded asphalt: new open-graded asphalt −2 dBA, stone mastic asphalt −1, 7 mm chip seal +2, 14 mm chip seal +4. Road pavement gets resurfaced on a cycle, we might as well put down quieter pavements when we can. Enforce Enforcement is our go-to policy, and we cannot abandon it. It is necessary for modified exhausts, organised racing and repeat offenders, and cameras and patrols can follow the problem as it moves. But we must also recognise it is selective by nature. And it addresses the problem that previous bad designs have created, and hopefully future good designs will prevent. What Parliament can do Three things, none of which requires another study. * Redesign. Self-enforcing 30 km/h design at noise hotspots, and on new residential, school and shopping streets. Fund calming along whole corridors, not single blocks. * Resurface. Fund low-noise surfaces, and specify them where people live. * Enforce. Objective noise limits that can be measured at the roadside, backed by cameras, patrols and inspections aimed at modified exhausts, organised racing and repeat offenders. All of which is to say: enforcement catches the offender, design removes the opportunity. FIN --- Notes Electric vehicles Electric propulsion is quieter, and below about 30 km/h that is most of the sound. Above it, tyre-road noise dominates and an electric car sounds like any other. Read more
000
Reposted by David M Levinson ⁂
Yonah Freemark @yonahfreemark.com · 25/09/2026
Brightline has filed for bankruptcy, hoping to slash $6 billion in debt. This is not expected to affect day-to-day operations.
ft.com
Private equity-backed Florida railway company Brightline files for bankruptcy
Orlando-to-Miami route seeking to popularise high-speed rail in US has filed for Chapter 11 to cut nearly $6bn in debt
03010
David M Levinson ⁂ @transportist.org · 24/09/2026
Designing for Quiet
dlvr.it
Designing for Quiet
Below summarises my presentation at a Forum on Vehicle-Generated Noise Pollution at New South Wales Parliament House on September 23. For my international readers, while noise is an issue in many places, in Australia this is an issue because of the popularity of hooning, anti-social operation of vehicles, especially noisy driving (modified engines, tyre burnouts (spinning the driven wheels while holding the car still), etc.) Wikipedia reports: A hoon (/huːn/ ⓘ) is an Australian and New Zealand term describing a person who deliberately drives a vehicle in a reckless or dangerous manner, generally in order to provoke a reaction from onlookers. Decibels If a tree falls in the forest and there is no-one there to hear it, does it make a sound? Of course. But does it make a noise? No. Noise is unwanted sound. It is a negative externality; it requires both someone making the noise and someone hearing it without wanting to. What matters to the person trying to sleep is how loud each event is and how many events there are. In contrast with intuition, decibels are logarithmic. One truck may be 80 dB, but two trucks are “only” 83 dB. Ten decibels more sounds about twice as loud, so a modified motorcycle at 90 dBA is heard as sixteen times louder than a 50 dBA street. A quiet street with one loud vehicle is worse than a busy one with a steady stream of vehicles. The background is low and every pass stands out. Money We have heard from my colleague Edmund Lau at the University of Sydney about the health effects of poor sleep, resulting from noise. But everything in Australia is about real estate. Hedonic studies of real estate prices near highways and airports give us a Noise Depreciation Index. Each additional decibel lowers the price of a house by about 0.62%. People don’t want to live near highways or under flight paths, and require a lower price to do so. Roads that invite it Some roads invite anti-social driving: long straight sections with clear sightlines, capacity to spare at night, connected loops that let a driver circulate and repeat the performance. Hard reflective surfaces, façades close to the carriageway, and light background traffic amplify the noise. Re-design Design works every hour on every driver. Geometry that enforces itself changes what speed feels natural, and it narrows the whole speed distribution, including the fast tail that does the damage. Design changes may comprise various sorts of traffic calming (but not all of them), including interventions like planting trees on the side of the road, to slow traffic. Isolated humps and stop signs produce the noisiest pattern available. Brake, sprint to the next device, brake again. The braking, the suspension and the re-acceleration all make noise. Continuous low-speed geometry is quieter: close-spaced plateaus, raised intersections, and small roundabouts, along with traffic signals timed to give a green wave at the target speed rather than a clear run. Diverters cut flows and speeds together. Lower speeds also lower the level. Zurich dropped limits from 50 to 30 km/h and measured about 1.6 to 1.7 dB less at building façades, with less annoyance and less disturbed sleep reported. Re-surface Transport for NSW notes that against dense-graded asphalt: new open-graded asphalt −2 dBA, stone mastic asphalt −1, 7 mm chip seal +2, 14 mm chip seal +4. Road pavement gets resurfaced on a cycle, we might as well put down quieter pavements when we can. Enforce Enforcement is our go-to policy, and we cannot abandon it. It is necessary for modified exhausts, organised racing and repeat offenders, and cameras and patrols can follow the problem as it moves. But we must also recognise it is selective by nature. And it addresses the problem that previous bad designs have created, and hopefully future good designs will prevent. What Parliament can do Three things, none of which requires another study. * Redesign. Self-enforcing 30 km/h design at noise hotspots, and on new residential, school and shopping streets. Fund calming along whole corridors, not single blocks. * Resurface. Fund low-noise surfaces, and specify them where people live. * Enforce. Objective noise limits that can be measured at the roadside, backed by cameras, patrols and inspections aimed at modified exhausts, organised racing and repeat offenders. All of which is to say: enforcement catches the offender, design removes the opportunity. FIN --- Notes Electric vehicles Electric propulsion is quieter, and below about 30 km/h that is most of the sound. Above it, tyre-road noise dominates and an electric car sounds like any other. Read more
000
Reposted by David M Levinson ⁂
Jennifer Ouellette @jenlucpiquant.bsky.social · 23/09/2026
After multiple deaths and injuries, NHTSA is investigating comma.ai arstechnica.com/cars/2026/09...
comma.ai
comma.ai — make driving chill
Hands free driving for the car you already have
3314
Reposted by David M Levinson ⁂
Michael Bell @xtrackka.bsky.social · 23/09/2026
#superficial intelligence 4 the win
011
David M Levinson ⁂ @transportist.org · 23/09/2026
I only want #superartificial intelligence not artificial #superintelligence.
100
Reposted by David M Levinson ⁂
Evergreen Intel @vcdgf555.bsky.social · 20/09/2026
This is suposedly the representation of last night's drone attacks on Moscow. Allegedly 1600 over all of Russia with well over 450 alone on Moscow (numbers require verification). I want to try something here: what do you see in the patterns? I'll give others a chance before I give my own thoughts.
5117922
Reposted by David M Levinson ⁂
Simon Kuestenmacher @simongerman600.bsky.social · 19/09/2026
This amazing little tool simply draws all streets in any city you want. As examples here are the town I grew up in (20k residents) and the city I live in (5M residents). Have a play with it. The exported screenshots make great desktop backgrounds. Source: buff.ly/2uht4vJ
45017
David M Levinson ⁂ @transportist.org · 19/09/2026
The Democrats should nominate Robert Prevost for President in 2028.
100
David M Levinson ⁂ @transportist.org · 18/09/2026
ICYMI: Universities: Selecting, Teaching, or Certifying?
dlvr.it
Universities: Selecting, Teaching, or Certifying?
There is a conflict at the heart of higher education: we are rewarded for teaching students and graduating them, but trusted to uphold standards that may require us to fail them. The institution selling the course also decides whether the customer has earned the certificate. Universities select students, enrol them in classes, and certify the result, and confuse success at one activity with success at the others. Selecting Do we really think firms hire Harvard graduates because of what they were taught in Cambridge rather than who was selected in the first place? Harvard has already done a screening exercise for the employer. So long as a student can comply sufficiently with the university system, they are awarded a degree four years later. That degree carries the screening information even before we ask what happened in the classroom. Universities and their associated admission processes are designed to sort prospective students into the best institution they can attain, subject to constraints of money, geography, admissions, and everything else. Then we rank the institutions using the outcomes of the people they selected. A university can admit excellent students, who applied because of the university’s historically accumulated reputation, and graduate excellent students without having added very much. Another can do a great deal for students who arrived less prepared and still look worse in the rankings. Teaching We can document that teaching took place. Classes were taught, assignments marked, rubrics applied, student surveys completed.1 There are Canvas engagement snapshots and peer observation notes. The file is complete. Accreditation adds its own bureaucracy. We map assessments to learning outcomes, learning outcomes to graduate attributes, and assemble reports showing that the mappings have been reviewed. External reviewers examine the evidence. We demonstrate that we have processes for assuring ourselves that students have learned. But an accredited course is not an independently examined graduate. Reviewing our assessments and marking practices still leaves the question of what graduates retain and can do without our prompts, rubrics, and rehearsed problems. The rubric may focus the student and the instructor on more specific knowledge at the expense of the general, or other specific knowledge not previously disentangled. By over-reliance on standards, we are treating education as if it were an industrial process, rather than a bespoke set of interactions that shape individual brains. How much of the effort spent documenting that we assess learning could go into finding out what actually survives? We have made the assurance of learning into a substantial administrative activity. We should demand evidence that the assurance itself is worth the work, we do more now than 30 years ago, but can’t show graduates are better. What did the students learn? What do graduates still know a few years later? Can they think better? These are the actual outcomes. They are not explicitly assessed. We may know where our graduates are. We already follow graduates into employment and track their salaries. We can ask about retained learning too. A salary and an understanding of a subject are different outcomes. The rest, our assessment of teaching, is paperwork about the process. Certifying A passing grade records achievement at the time of assessment. Those assessments are developed by the instructors themselves. An assessment does not establish that the knowledge was retained, or that the student can use it when the problem looks different. We make a considerable leap from completing the course to having acquired an education. A rank records relative position, not an absolute standard. Somebody has to finish last. They need not be incompetent. Somebody has to finish first. They need not be competent. Would you cross a bridge designed by the best student in a class where nobody understood structural mechanics? The student wants to pass. The university wants the student to remain enrolled and complete. Our officials celebrate higher passing rates. Society wants the qualification to mean something. When those interests diverge, whom do we serve: the customer, or the society subsidising the education and relying on its standards? This arrangement deserves more scrutiny than it gets. Assess the achievement Society should demand the separation of teaching from at least some of the assessment. An independent assessment should ask whether the student can do what the qualification promises. Where they learned it should be a different question. If they learned from books, work, or another teacher, the knowledge is still knowledge, the capability exists. This would also make the teaching itself easier to evaluate. Establish what students can do when they enter. Examine what they can do when upon exit. Follow up with a sample later and find out what survived. For example, give them a problem they have not rehearsed and require them to explain it orally. An engineer should be able to reason through a design, identify what could go wrong, and defend the assumptions. We should be interested in the student’s understanding as well as the submitted document.2 The problem is that accreditation locks in old knowledge. New material must displace the old, not just accumulate. What makes a good transport engineer in 2026 should be different from what was standard when I was a student. But independent of the specific curriculum, the point here is to establish what the test-taker knows and can do. Comparing that with what they knew on entry gives us evidence about what the education added. We should not assume the conclusion before doing the assessment. That would not survive the most basic academic peer review. And the lectures? If you had asked me in the 1450s about Gutenberg’s printing press, I would have thought it sufficient to decimate traditional higher education. Once you know how to read, why do you need lectures? Demonstrations, discussions, tutoring, laboratory experiments, sure. But lectures? The oral tradition should have fallen by the wayside centuries ago. Will AI finally do what the printing press did not? I mean, who knows? Are universities on a long slow decline, or are we operating in the world of cartoon physics?Wile E. Coyote will not fall until he realises he is no longer supported.1 Big rubric has been growing in size, I am unclear why it keeps getting fed. It is the appearance of fairness and efficiency I suppose, powered by the rubric-industrial complex (e.g. https://community.instructure.com/en/kb/articles/661102-how-do-i-add-a-rubric-to-an-assignment)2 In the US, Engineers (mostly Civil Engineers) sit the Fundamentals of Engineering exam around graduation and the Principles and Practice exam (and if passing become Professional Engineers) after about four years of work. NCEES writes and scores both. The university that taught the candidate does not. Neither exam is required to work as an engineer: the industrial exemption lets a company do its own in-house engineering unsealed. The licence is required to offer services to the public and to stamp drawings. The bar exam is required to practise law in almost every state. Wisconsin admits graduates of its two law schools without it, and Oregon, Washington, New Hampshire, Minnesota, and New Mexico have built supervised-practice or portfolio routes. Medicine examines most. USMLE Steps 1, 2, and 3 run from the second year of medical school into the first years of residency. After residency comes specialty board certification, a separate examination by one of the 24 ABMS member boards, and then continuing certification for the rest of a career. FIN Read more
000
David M Levinson ⁂ @transportist.org · 17/09/2026
MacOS Tilcayo — New cat species identified in Bolivia, first in over a century -
reuters.com
New cat species identified in Bolivia, first in over a century
A diminutive wild cat that inhabits Bolivia's cloud forest has been identified as a previously unknown species, marking the first time a new living cat species has been formally named and described ​in more than a century.
000
David M Levinson ⁂ @transportist.org · 17/09/2026
ICYMI: Dr. Amin Shaer
dlvr.it
Dr. Amin Shaer
Congratulations to Dr. Amin Shaer for “satisfying the requirements for the award of the degree of Doctor of Philosophy at the University of Sydney.” Thesis Title: Detecting Dangerous Driving Lead Supervisor: Professor David Levinson. Abstract: Risky driving behaviors contribute to road crashes, which impose major social and economic burdens. To tackle this phenomenon, this thesis develops two main ideas. First, it examines what factors influence the choice to drive after visiting alcohol-serving establishments (ASEs), where driving may be riskier due to impairment, late-night travel, fatigue, and reduced attention. This then motivates the rest of the thesis, which uses computer vision to detect and measure dangerous and unusual driving behaviors from traffic-camera footage, linking this early-stage risk context to objective indicators of near-crashes and crash risk. In this thesis, we begin by examining the factors influencing the choice to drive from alcohol-serving establishments (ASEs) using the Victorian Integrated Survey of Travel and Activity (VISTA) dataset. The thesis then shows how computer vision and existing roadside traffic cameras can be used to: (1) detect dangerous driving behaviors such as speeding, short headway, lane violations, and aggressive driving; (2) compare road safety indicators under different weather conditions; and (3) detect unusual driving behaviors such as slipping, running off the road, passing on the shoulder, and abrupt stopping. The results of the first part of the thesis show that people tended to drive for longer ASEs and walk for shorter ones. Going home made driving more likely, while going to other social activities did not show the same pattern. Men were more likely than women to drive after visiting ASEs. In addition, short travel distances (
000
David M Levinson ⁂ @transportist.org · 17/09/2026
Universities: Selecting, Teaching, or Certifying?
dlvr.it
Universities: Selecting, Teaching, or Certifying?
There is a conflict at the heart of higher education: we are rewarded for teaching students and graduating them, but trusted to uphold standards that may require us to fail them. The institution selling the course also decides whether the customer has earned the certificate. Universities select students, enrol them in classes, and certify the result, and confuse success at one activity with success at the others. Selecting Do we really think firms hire Harvard graduates because of what they were taught in Cambridge rather than who was selected in the first place? Harvard has already done a screening exercise for the employer. So long as a student can comply sufficiently with the university system, they are awarded a degree four years later. That degree carries the screening information even before we ask what happened in the classroom. Universities and their associated admission processes are designed to sort prospective students into the best institution they can attain, subject to constraints of money, geography, admissions, and everything else. Then we rank the institutions using the outcomes of the people they selected. A university can admit excellent students, who applied because of the university’s historically accumulated reputation, and graduate excellent students without having added very much. Another can do a great deal for students who arrived less prepared and still look worse in the rankings. Teaching We can document that teaching took place. Classes were taught, assignments marked, rubrics applied, student surveys completed.1 There are Canvas engagement snapshots and peer observation notes. The file is complete. Accreditation adds its own bureaucracy. We map assessments to learning outcomes, learning outcomes to graduate attributes, and assemble reports showing that the mappings have been reviewed. External reviewers examine the evidence. We demonstrate that we have processes for assuring ourselves that students have learned. But an accredited course is not an independently examined graduate. Reviewing our assessments and marking practices still leaves the question of what graduates retain and can do without our prompts, rubrics, and rehearsed problems. The rubric may focus the student and the instructor on more specific knowledge at the expense of the general, or other specific knowledge not previously disentangled. By over-reliance on standards, we are treating education as if it were an industrial process, rather than a bespoke set of interactions that shape individual brains. How much of the effort spent documenting that we assess learning could go into finding out what actually survives? We have made the assurance of learning into a substantial administrative activity. We should demand evidence that the assurance itself is worth the work, we do more now than 30 years ago, but can’t show graduates are better. What did the students learn? What do graduates still know a few years later? Can they think better? These are the actual outcomes. They are not explicitly assessed. We may know where our graduates are. We already follow graduates into employment and track their salaries. We can ask about retained learning too. A salary and an understanding of a subject are different outcomes. The rest, our assessment of teaching, is paperwork about the process. Certifying A passing grade records achievement at the time of assessment. Those assessments are developed by the instructors themselves. An assessment does not establish that the knowledge was retained, or that the student can use it when the problem looks different. We make a considerable leap from completing the course to having acquired an education. A rank records relative position, not an absolute standard. Somebody has to finish last. They need not be incompetent. Somebody has to finish first. They need not be competent. Would you cross a bridge designed by the best student in a class where nobody understood structural mechanics? The student wants to pass. The university wants the student to remain enrolled and complete. Our officials celebrate higher passing rates. Society wants the qualification to mean something. When those interests diverge, whom do we serve: the customer, or the society subsidising the education and relying on its standards? This arrangement deserves more scrutiny than it gets. Assess the achievement Society should demand the separation of teaching from at least some of the assessment. An independent assessment should ask whether the student can do what the qualification promises. Where they learned it should be a different question. If they learned from books, work, or another teacher, the knowledge is still knowledge, the capability exists. This would also make the teaching itself easier to evaluate. Establish what students can do when they enter. Examine what they can do when upon exit. Follow up with a sample later and find out what survived. For example, give them a problem they have not rehearsed and require them to explain it orally. An engineer should be able to reason through a design, identify what could go wrong, and defend the assumptions. We should be interested in the student’s understanding as well as the submitted document.2 The problem is that accreditation locks in old knowledge. New material must displace the old, not just accumulate. What makes a good transport engineer in 2026 should be different from what was standard when I was a student. But independent of the specific curriculum, the point here is to establish what the test-taker knows and can do. Comparing that with what they knew on entry gives us evidence about what the education added. We should not assume the conclusion before doing the assessment. That would not survive the most basic academic peer review. And the lectures? If you had asked me in the 1450s about Gutenberg’s printing press, I would have thought it sufficient to decimate traditional higher education. Once you know how to read, why do you need lectures? Demonstrations, discussions, tutoring, laboratory experiments, sure. But lectures? The oral tradition should have fallen by the wayside centuries ago. Will AI finally do what the printing press did not? I mean, who knows? Are universities on a long slow decline, or are we operating in the world of cartoon physics?Wile E. Coyote will not fall until he realises he is no longer supported.1 Big rubric has been growing in size, I am unclear why it keeps getting fed. It is the appearance of fairness and efficiency I suppose, powered by the rubric-industrial complex (e.g. https://community.instructure.com/en/kb/articles/661102-how-do-i-add-a-rubric-to-an-assignment)2 In the US, Engineers (mostly Civil Engineers) sit the Fundamentals of Engineering exam around graduation and the Principles and Practice exam (and if passing become Professional Engineers) after about four years of work. NCEES writes and scores both. The university that taught the candidate does not. Neither exam is required to work as an engineer: the industrial exemption lets a company do its own in-house engineering unsealed. The licence is required to offer services to the public and to stamp drawings. The bar exam is required to practise law in almost every state. Wisconsin admits graduates of its two law schools without it, and Oregon, Washington, New Hampshire, Minnesota, and New Mexico have built supervised-practice or portfolio routes. Medicine examines most. USMLE Steps 1, 2, and 3 run from the second year of medical school into the first years of residency. After residency comes specialty board certification, a separate examination by one of the 24 ABMS member boards, and then continuing certification for the rest of a career. FIN Read more
000
David M Levinson ⁂ @transportist.org · 16/09/2026
Urbanists were all over the "obesity epidemic " where are they on the "fertility collapse " ?
100
David M Levinson ⁂ @transportist.org · 15/09/2026
Dr. Amin Shaer
dlvr.it
Dr. Amin Shaer
Congratulations to Dr. Amin Shaer for “satisfying the requirements for the award of the degree of Doctor of Philosophy at the University of Sydney.” Thesis Title: Detecting Dangerous Driving Lead Supervisor: Professor David Levinson. Abstract: Risky driving behaviors contribute to road crashes, which impose major social and economic burdens. To tackle this phenomenon, this thesis develops two main ideas. First, it examines what factors influence the choice to drive after visiting alcohol-serving establishments (ASEs), where driving may be riskier due to impairment, late-night travel, fatigue, and reduced attention. This then motivates the rest of the thesis, which uses computer vision to detect and measure dangerous and unusual driving behaviors from traffic-camera footage, linking this early-stage risk context to objective indicators of near-crashes and crash risk. In this thesis, we begin by examining the factors influencing the choice to drive from alcohol-serving establishments (ASEs) using the Victorian Integrated Survey of Travel and Activity (VISTA) dataset. The thesis then shows how computer vision and existing roadside traffic cameras can be used to: (1) detect dangerous driving behaviors such as speeding, short headway, lane violations, and aggressive driving; (2) compare road safety indicators under different weather conditions; and (3) detect unusual driving behaviors such as slipping, running off the road, passing on the shoulder, and abrupt stopping. The results of the first part of the thesis show that people tended to drive for longer ASEs and walk for shorter ones. Going home made driving more likely, while going to other social activities did not show the same pattern. Men were more likely than women to drive after visiting ASEs. In addition, short travel distances (
000
David M Levinson ⁂ @transportist.org · 10/09/2026
ICYMI: Fare enough: A quantitative spatial transport model for transit pricing
dlvr.it
Fare enough: A quantitative spatial transport model for transit pricing
Recently published: * Mann, I. and Levinson, D. M. (2026) Fare enough: A quantitative spatial transport model for transit pricing. Transportation Research Part A: Policy and Practice, Volume 214, December 2026, 105237. [doi] Standard transport appraisal treats fare regulation in isolation, ignoring how price signals reshape urban geography. We bridge regulatory practice and quantitative spatial economics by constructing a Quantitative Spatial Transport Model (QSTM) for Greater Sydney, endogenising household and firm locations in response to transport shocks. Our framework extends the canonical quantitative spatial model by endogenising commuter mode choice and internalising network externalities through road congestion and the Mohring effect. Evaluating three public transport pricing interventions, including zero-fare, flat-fare, and fare-cap policies, we find that free transit is welfare-suboptimal, driven largely by operator revenue losses. In our setting, distance-based fares provide a spatial price signal that helps internalise resource costs and discourage sprawl, a signal that uniform flat fares mute. The model demonstrates that allocative efficiency requires a higher user contribution, revealing that weekly fare caps function as implicit subsidies for long-distance commuters. Higher fares trigger a spatial reorganisation where residents centralise to minimise commuting costs and firms decentralise to access labour. Ultimately, efficient distance-based pricing promotes a compact residential form, encourages polycentric employment, and reduces operator resource costs. Keywords: Quantitative spatial models, Transport appraisal, Fare regulation, Agglomeration economies, Spatial general equilibrium, Urban economicsFig. 9. Spatial reorganisation of the urban economy under removal of the weekly fare cap. The maps display the percentage deviation from the base case for residential location, employment distribution, wages, residential and commercial floorspace prices, and total factor productivity.
010
David M Levinson ⁂ @transportist.org · 10/09/2026
Did Siri write the Keynote?
000
David M Levinson ⁂ @transportist.org · 09/09/2026
The expression "matters most" should be banned. Cc John Ternus.
000
David M Levinson ⁂ @transportist.org · 09/09/2026
A communication-free decentralised two-dimensional trajectory controller for autonomous vehicles on a lane-free road: A level-k game approach Recently published: Wang, Z., Ramezani, M. and Levinson, D. (2027) A communication-free decentralised two-dimensional trajectory controller for autonomous…
transportist.org
A communication-free decentralised two-dimensional trajectory controller for autonomous vehicles on a lane-free road: A level-k game approach
Recently published: Wang, Z., Ramezani, M. and Levinson, D. (2027) A communication-free decentralised two-dimensional trajectory controller for autonomous vehicles on a lane-free road: A level-k game approach. Transportation Research Part C: Emerging Technologies, Volume 194, January 2027, 105959. [doi] This paper proposes a two-dimensional trajectory controller (2DTC) for autonomous vehicles (AVs) operating on a lane-free freeway. Without relying on inter-vehicle communication, each AV independently determines its acceleration and steering in real time.
000
David M Levinson ⁂ @transportist.org · 09/09/2026
Fare enough: A quantitative spatial transport model for transit pricing Recently published: Mann, I. and Levinson, D. M. (2026) Fare enough: A quantitative spatial transport model for transit pricing. Transportation Research Part A: Policy and Practice, Volume 214, December 2026, 105237. [doi]…
transportist.org
Fare enough: A quantitative spatial transport model for transit pricing
Recently published: Mann, I. and Levinson, D. M. (2026) Fare enough: A quantitative spatial transport model for transit pricing. Transportation Research Part A: Policy and Practice, Volume 214, December 2026, 105237. [doi] Standard transport appraisal treats fare regulation in isolation, ignoring how price signals reshape urban geography. We bridge regulatory practice and quantitative spatial economics by constructing a Quantitative Spatial Transport Model (QSTM) for Greater Sydney, endogenising household and firm locations in response to transport shocks.
000
David M Levinson ⁂ @transportist.org · 08/09/2026
Fare enough: A quantitative spatial transport model for transit pricing
dlvr.it
Fare enough: A quantitative spatial transport model for transit pricing
Recently published: * Mann, I. and Levinson, D. M. (2026) Fare enough: A quantitative spatial transport model for transit pricing. Transportation Research Part A: Policy and Practice, Volume 214, December 2026, 105237. [doi] Standard transport appraisal treats fare regulation in isolation, ignoring how price signals reshape urban geography. We bridge regulatory practice and quantitative spatial economics by constructing a Quantitative Spatial Transport Model (QSTM) for Greater Sydney, endogenising household and firm locations in response to transport shocks. Our framework extends the canonical quantitative spatial model by endogenising commuter mode choice and internalising network externalities through road congestion and the Mohring effect. Evaluating three public transport pricing interventions, including zero-fare, flat-fare, and fare-cap policies, we find that free transit is welfare-suboptimal, driven largely by operator revenue losses. In our setting, distance-based fares provide a spatial price signal that helps internalise resource costs and discourage sprawl, a signal that uniform flat fares mute. The model demonstrates that allocative efficiency requires a higher user contribution, revealing that weekly fare caps function as implicit subsidies for long-distance commuters. Higher fares trigger a spatial reorganisation where residents centralise to minimise commuting costs and firms decentralise to access labour. Ultimately, efficient distance-based pricing promotes a compact residential form, encourages polycentric employment, and reduces operator resource costs. Keywords: Quantitative spatial models, Transport appraisal, Fare regulation, Agglomeration economies, Spatial general equilibrium, Urban economicsFig. 9. Spatial reorganisation of the urban economy under removal of the weekly fare cap. The maps display the percentage deviation from the base case for residential location, employment distribution, wages, residential and commercial floorspace prices, and total factor productivity.
023
Reposted by David M Levinson ⁂
mr. TIM @timkellogg.me · 07/09/2026
fair point — maybe Astra is capable of great inventions, but until it does, is it really AGI?
François Chollet • @fchollet 22m
X
The narrative around why building AGI was a good idea has always been about invention --
"it will cure cancer", "it will solve fusion energy".
etc.
So I would not "declare AGI" until we have Al that is, at last, capable of invention --conceptual breakthroughs, novel insights, new real-world technology, etc.
8312
David M Levinson ⁂ @transportist.org · 04/09/2026
ICYMI: Transportist: September 2026
dlvr.it
Transportist: September 2026
If you are reading this I survived open heart surgery to remove a Myxoma from my left atrium. Benign tumours can come for you too. Posts
020
David M Levinson ⁂ @transportist.org · 02/09/2026
Transportist: September 2026 If you are reading this I survived open heart surgery to remove a Myxoma from my left atrium. Benign tumours can come for you too. Posts Publications Pointers Your Regular Reminder Car ramming in Normandy, France AVs Waymo involved in fatal crash, but probably not the…
transportist.org
Transportist: September 2026
If you are reading this I survived open heart surgery to remove a Myxoma from my left atrium. Benign tumours can come for you too. Posts Publications Pointers Your Regular Reminder Car ramming in Normandy, France AVs Waymo involved in fatal crash, but probably not the cause Waymo lifts the lid on the ‘brain’ powering its robotaxis EVs The state of battery-swapping EVs…
140
Reposted by David M Levinson ⁂
Simon Kuestenmacher @simongerman600.bsky.social · 02/09/2026
This map of US Interstate exits doubles as a population density map. Exits cluster across the urbanised eastern half and around major cities. Head into the sparsely populated Great Plains, deserts and Mountain West, and the distance to the next exit grows dramatically. Source: buff.ly/bIKXHFJ
0205
David M Levinson ⁂ @transportist.org · 02/09/2026
Transportist: September 2026
dlvr.it
Transportist: September 2026
If you are reading this I survived open heart surgery to remove a Myxoma from my left atrium. Benign tumours can come for you too. Posts
010
David M Levinson ⁂ @transportist.org · 02/09/2026
ICYMI: How Borderline High Cholesterol Saved My Life
dlvr.it
How Borderline High Cholesterol Saved My Life
I have returned to work after an unplanned excursion into the Australian health care system, including open-heart surgery. My general practitioner (GP) was concerned about my cholesterol1 levels, particularly given my family history. He had prescribed statins. With more than 1/4 of adults in my age group on statins, this was not uncommon. Statins did not go well. I am apparently statin-intolerant.2 They made me feel like I had a constant fever: muscle aches, tired, and what I imagine being 20 years older feels like, what the doctor called myalgia. We tried another statin to no avail. So, rather than continuing to speculate about how much of a problem my cholesterol actually was, my GP sent me for a CT scan3 to look for calcification in the coronary arteries. The result on that front was mild calcification on left anterior descending (calcium score of 50) (65th percentile).4 So the cholesterol level was not a major problem, all things considered. The scan did, however, find something else. There’s a little black spot on my heart today The CT showed a suspected cardiac myxoma in my left atrium. What’s a cardiac myxoma?5 It is a rare,6 usually benign tumour that grows inside the heart. “Benign” is doing a fair bit of work in that sentence. It means the tumour isn’t cancerous. It does not mean that having a large tumour floating around inside your heart is a good idea, or even not harmful. An echocardiogram corroborated. Mine was initially estimated at about 50 mm across and occupied a substantial fraction of my left atrium. This provides definitive evidence that I do, in fact, have a heart. It also suggests that mine is considerably more efficient than everyone else’s, given how well it had been doing its job while being starved of space. The problem with a myxoma is not simply that it takes up space. If it gets large enough, it can obstruct blood flow through the atrial valve. Also, they are “friable,” meaning bits can break off, enter the bloodstream, and go places where bits of heart tumour really ought not go. In retrospect, it also provided an explanation for health problems I had been experiencing that nobody had previously connected to my heart. My doctor had not been looking for a myxoma. There was no particular reason he should have been, given their rarity. One week after it was discovered, I was in Strathfield Private Hospital having open-heart surgery to remove it.My heart before surgery: Axial contrast-enhanced CT image of the chest demonstrating a large low-attenuation filling defect within the left atrium, subsequently identified as a left atrial myxoma. Everybody has an open heart I had never had major surgery before. I also don’t think I have taken a real sick day in my academic career. I have taught through pneumonia and through laryngitis, although I ended a class early that day.7 Open-heart surgery is another matter though. Among the instructions on leaving hospital was that I would not be able to drive a car for several weeks. Ha. I also did not, however, ride a bicycle to or from the hospital. My myxoma The tumour was successfully removed from my left atrium. It was as expected a myxoma and benign, but after extraction measured at roughly 70 mm, confirming that removing it was the right strategy. The surgery involved stopping my heart and lungs, so I was kept alive by machines in the interim. I of course only know this because I was told, having been unconscious through the experience. Technically they opened me up twice, since there was still internal bleeding after they closed me the first time. Lovely. Recovery from having one’s chest opened is not instantaneous. The first week in hospital was miserable, both because of the surgery and the tubes and because of being in hospital with all the machines that go ping. Walking, breathing, sleeping, coughing, and figuring out how to get out of a chair became more challenging than I remembered. But the operation went well, the myxoma is gone, I have spent a month recovering (and will spend at least another two months they tell me, but I am fine to do anything not involving heavy lifting) and I am back at on campus facing a month of computer software needing updates which for whatever reason they need to waste my time for instead of doing when I wasn’t here for a month, with the computer on. Causal Chain The chain of causation here. * My cholesterol was moderately high. * My GP worried about it. * I couldn’t tolerate the obvious treatment. * That led to further investigation. * The investigation showed that the cholesterol was not, in fact, doing very much damage. * And in establishing that, the scan happened to find a large tumour in my heart before it could cause a stroke, obstruct blood flow, or do something else unpleasant. * So my borderline high cholesterol may have saved my life. My thanks to my GP for following up something that would have been easy to dismiss, and to the cardiologists, surgeons, nurses, physiotherapists, and other staff who diagnosed the problem, got me through surgery, and put me back together at Strathfield Private Hospital, and the cardio-physio group at St. George’s Hospital. Also thanks to the health care system in Australia, I am out-of-pocket well less than $AU10k for the whole thing. Also thanks to family and colleagues for picking up the slack.1 AI tells me “High cholesterol is bad because it can lead to plaque building up in your arteries, which can narrow or clog them and reduce blood flow to your heart and other organs.” 2 I suspect strongly that Big Statin is trying to cover up the incidence of statin intolerance. But maybe I am just lucky.3 I describe the CT scan as the worst amusement park ride ever. You lie on your back and they move you backwards and forwards while scanning you. Not painful (and not as claustrophobic as an MRI).One of many hospital beds I occupied at Strathfield Private Hospital. This was I am sure pre-operation, though I think I had 4 different rooms over the 8 days I was there. Then the surgery, then intensive care, then cardiac ward, then regular ward.4 Calcium score of 50, consistent with mild 10-year estimated CVD risk. The burden of non-calcified plaque is estimated at 50% total plaque volume.5 There is also a Myxoma virus which gives Myxomatosis (tumors) to rabbits and is used for control. This is not that.6 It is estimated that fewer than 1 in a million people per year have surgery to remove a cardiac myxoma annually in Australia. I am even more lucky.7 Sure, I sometimes worked from home before COVID, back when doing so was less common, if going to campus wasn’t worth the trip. But much of my work involves a computer, and it isn’t as though the computer goes unvisited on weekends. Academics are nominally paid according to days and hours. I regard that as a legacy of archaic work rules imposed by the backwards labour arrangements of a university system in which both labour and management seem adamant to retain the assembly-line model of production. I regard myself as a professional. I work for outputs rather than inputs, and hope to be assessed that way as well. If I can produce the same output with fewer inputs, that should be regarded as an improvement in productivity, not evidence that somebody has failed to extract enough hours from me or enough dollars from funders, academia is irretrievably broken and there is a long chain of university administrators who bear responsibility. FIN Read more
010
David M Levinson ⁂ @transportist.org · 01/09/2026
How Borderline High Cholesterol Saved My Life I have returned to work after an unplanned excursion into the Australian health care system, including open-heart surgery. My general practitioner (GP) was concerned about my cholesterol1 levels, particularly given my family history. He had prescribed…
transportist.org
How Borderline High Cholesterol Saved My Life
I have returned to work after an unplanned excursion into the Australian health care system, including open-heart surgery. My general practitioner (GP) was concerned about my cholesterol1 levels, particularly given my family history. He had prescribed statins. With more than 1/4 of adults in my age group on statins, this was not uncommon. Statins did not go well. I am apparently statin-intolerant.
110
David M Levinson ⁂ @transportist.org · 01/09/2026
How Borderline High Cholesterol Saved My Life
dlvr.it
How Borderline High Cholesterol Saved My Life
I have returned to work after an unplanned excursion into the Australian health care system, including open-heart surgery. My general practitioner (GP) was concerned about my cholesterol1 levels, particularly given my family history. He had prescribed statins. With more than 1/4 of adults in my age group on statins, this was not uncommon. Statins did not go well. I am apparently statin-intolerant.2 They made me feel like I had a constant fever: muscle aches, tired, and what I imagine being 20 years older feels like, what the doctor called myalgia. We tried another statin to no avail. So, rather than continuing to speculate about how much of a problem my cholesterol actually was, my GP sent me for a CT scan3 to look for calcification in the coronary arteries. The result on that front was mild calcification on left anterior descending (calcium score of 50) (65th percentile).4 So the cholesterol level was not a major problem, all things considered. The scan did, however, find something else. There’s a little black spot on my heart today The CT showed a suspected cardiac myxoma in my left atrium. What’s a cardiac myxoma?5 It is a rare,6 usually benign tumour that grows inside the heart. “Benign” is doing a fair bit of work in that sentence. It means the tumour isn’t cancerous. It does not mean that having a large tumour floating around inside your heart is a good idea, or even not harmful. An echocardiogram corroborated. Mine was initially estimated at about 50 mm across and occupied a substantial fraction of my left atrium. This provides definitive evidence that I do, in fact, have a heart. It also suggests that mine is considerably more efficient than everyone else’s, given how well it had been doing its job while being starved of space. The problem with a myxoma is not simply that it takes up space. If it gets large enough, it can obstruct blood flow through the atrial valve. Also, they are “friable,” meaning bits can break off, enter the bloodstream, and go places where bits of heart tumour really ought not go. In retrospect, it also provided an explanation for health problems I had been experiencing that nobody had previously connected to my heart. My doctor had not been looking for a myxoma. There was no particular reason he should have been, given their rarity. One week after it was discovered, I was in Strathfield Private Hospital having open-heart surgery to remove it.My heart before surgery: Axial contrast-enhanced CT image of the chest demonstrating a large low-attenuation filling defect within the left atrium, subsequently identified as a left atrial myxoma. Everybody has an open heart I had never had major surgery before. I also don’t think I have taken a real sick day in my academic career. I have taught through pneumonia and through laryngitis, although I ended a class early that day.7 Open-heart surgery is another matter though. Among the instructions on leaving hospital was that I would not be able to drive a car for several weeks. Ha. I also did not, however, ride a bicycle to or from the hospital. My myxoma The tumour was successfully removed from my left atrium. It was as expected a myxoma and benign, but after extraction measured at roughly 70 mm, confirming that removing it was the right strategy. The surgery involved stopping my heart and lungs, so I was kept alive by machines in the interim. I of course only know this because I was told, having been unconscious through the experience. Technically they opened me up twice, since there was still internal bleeding after they closed me the first time. Lovely. Recovery from having one’s chest opened is not instantaneous. The first week in hospital was miserable, both because of the surgery and the tubes and because of being in hospital with all the machines that go ping. Walking, breathing, sleeping, coughing, and figuring out how to get out of a chair became more challenging than I remembered. But the operation went well, the myxoma is gone, I have spent a month recovering (and will spend at least another two months they tell me, but I am fine to do anything not involving heavy lifting) and I am back at on campus facing a month of computer software needing updates which for whatever reason they need to waste my time for instead of doing when I wasn’t here for a month, with the computer on. Causal Chain The chain of causation here. * My cholesterol was moderately high. * My GP worried about it. * I couldn’t tolerate the obvious treatment. * That led to further investigation. * The investigation showed that the cholesterol was not, in fact, doing very much damage. * And in establishing that, the scan happened to find a large tumour in my heart before it could cause a stroke, obstruct blood flow, or do something else unpleasant. * So my borderline high cholesterol may have saved my life. My thanks to my GP for following up something that would have been easy to dismiss, and to the cardiologists, surgeons, nurses, physiotherapists, and other staff who diagnosed the problem, got me through surgery, and put me back together at Strathfield Private Hospital, and the cardio-physio group at St. George’s Hospital. Also thanks to the health care system in Australia, I am out-of-pocket well less than $AU10k for the whole thing. Also thanks to family and colleagues for picking up the slack.1 AI tells me “High cholesterol is bad because it can lead to plaque building up in your arteries, which can narrow or clog them and reduce blood flow to your heart and other organs.” 2 I suspect strongly that Big Statin is trying to cover up the incidence of statin intolerance. But maybe I am just lucky.3 I describe the CT scan as the worst amusement park ride ever. You lie on your back and they move you backwards and forwards while scanning you. Not painful (and not as claustrophobic as an MRI).One of many hospital beds I occupied at Strathfield Private Hospital. This was I am sure pre-operation, though I think I had 4 different rooms over the 8 days I was there. Then the surgery, then intensive care, then cardiac ward, then regular ward.4 Calcium score of 50, consistent with mild 10-year estimated CVD risk. The burden of non-calcified plaque is estimated at 50% total plaque volume.5 There is also a Myxoma virus which gives Myxomatosis (tumors) to rabbits and is used for control. This is not that.6 It is estimated that fewer than 1 in a million people per year have surgery to remove a cardiac myxoma annually in Australia. I am even more lucky.7 Sure, I sometimes worked from home before COVID, back when doing so was less common, if going to campus wasn’t worth the trip. But much of my work involves a computer, and it isn’t as though the computer goes unvisited on weekends. Academics are nominally paid according to days and hours. I regard that as a legacy of archaic work rules imposed by the backwards labour arrangements of a university system in which both labour and management seem adamant to retain the assembly-line model of production. I regard myself as a professional. I work for outputs rather than inputs, and hope to be assessed that way as well. If I can produce the same output with fewer inputs, that should be regarded as an improvement in productivity, not evidence that somebody has failed to extract enough hours from me or enough dollars from funders, academia is irretrievably broken and there is a long chain of university administrators who bear responsibility. FIN Read more
000
Reposted by David M Levinson ⁂
Lewis Lehe @lewislehe.bsky.social · 31/08/2026
MS student Ben O'Brien from my research group has published an R package: transittraj. It takes TIDES data (AVL data standard) and GTFS and interpolates vehicle trajectories, including both location and speed trajectories. cran.r-project.org/web/packages...
cran.r-project.org
transittraj: Reconstruct and Visualize Transit Vehicle Trajectories
Today's public transit vehicles produce a large amount of automatic vehicle location (AVL) data. This data is very useful for planning and performance studies, but can be noisy, error-prone, and spars...
6163
David M Levinson ⁂ @transportist.org · 31/08/2026
Nice summary of the issues
010
Reposted by David M Levinson ⁂
David Ho @davidho.bsky.social · 27/08/2026
Cars are weapons
lemonde.fr
Car ramming in Normandy leaves one dead, 10 injured
One person died and 10 were injured after a man drove a car into a group of people in the city of Caen in France's northwest Normandy region on Wednesday. Police said they believe the incident occurre...
38614
Reposted by David M Levinson ⁂
Jarrett Walker @humantransit.bsky.social · 26/08/2026
US Transportation Secretary Duffy is out there bragging that they'll soon be letting SUVs and trucks be loud again, so as to more effectively draw attention to the fragility of the driver's masculinity. So it's time to remind people of this: carbuzz.com/study-links-...
carbuzz.com
Psychopaths And Sadists Like Loud Exhausts, Says Study
A new study from a Canadian university reveals that those who like loud combustion noises may have
73708215
David M Levinson ⁂ @transportist.org · 26/08/2026
ICYMI: Testing Pedestrian Flow and Delay Estimation from First-Actuation Latency
dlvr.it
Testing Pedestrian Flow and Delay Estimation from First-Actuation Latency
Recently published: * Levinson, D. (2026) Testing Pedestrian Flow and Delay Estimation from First-Actuation Latency. Findings, August 20, 2026. [doi] Traffic signal controllers timestamp the first pedestrian actuation that requests service, but they do not count the people arriving before the Walk indication. We test a theory-based estimator that treats the time from flashing-don’t-walk onset to first actuation as a censored waiting-time observation from a Poisson arrival-event process. The inferred event count and delay are calibrated separately to observed pedestrian counts and observed delay. Fourteen manually observed cases give mean adjustments of 2.202 for counts and 2.176 for delay assuming 100% compliance. A separate 24-leg-session video dataset gives 2.203 and 2.233. Held-out count errors are 23.9% and 22.4%. Observed behavior reduces delay from 16.606 to 15.996 pedestrian-hours in the manual data and from 12.934 to 8.522 hours in video. Keywords: pedestrian counts, pedestrian actuation, Poisson arrivals, signal delay, noncompliance, traffic signals, SCATS, SydneyFigure 1.Probability densities and case ranges for MCAV count, MCAV delay assuming 100% compliance, and video count adjustments. The shaded band is the MCAV count interquartile range.
000
David M Levinson ⁂ @transportist.org · 24/08/2026
Testing Pedestrian Flow and Delay Estimation from First-Actuation Latency Recently published: Levinson, D. (2026) Testing Pedestrian Flow and Delay Estimation from First-Actuation Latency. Findings, August 20, 2026. [doi] Traffic signal controllers timestamp the first pedestrian actuation that…
transportist.org
Testing Pedestrian Flow and Delay Estimation from First-Actuation Latency
Recently published: Levinson, D. (2026) Testing Pedestrian Flow and Delay Estimation from First-Actuation Latency. Findings, August 20, 2026. [doi] Traffic signal controllers timestamp the first pedestrian actuation that requests service, but they do not count the people arriving before the Walk indication. We test a theory-based estimator that treats the time from flashing-don’t-walk onset to first actuation as a censored waiting-time observation from a Poisson arrival-event process.
000
David M Levinson ⁂ @transportist.org · 24/08/2026
Testing Pedestrian Flow and Delay Estimation from First-Actuation Latency
dlvr.it
Testing Pedestrian Flow and Delay Estimation from First-Actuation Latency
Recently published: * Levinson, D. (2026) Testing Pedestrian Flow and Delay Estimation from First-Actuation Latency. Findings, August 20, 2026. [doi] Traffic signal controllers timestamp the first pedestrian actuation that requests service, but they do not count the people arriving before the Walk indication. We test a theory-based estimator that treats the time from flashing-don’t-walk onset to first actuation as a censored waiting-time observation from a Poisson arrival-event process. The inferred event count and delay are calibrated separately to observed pedestrian counts and observed delay. Fourteen manually observed cases give mean adjustments of 2.202 for counts and 2.176 for delay assuming 100% compliance. A separate 24-leg-session video dataset gives 2.203 and 2.233. Held-out count errors are 23.9% and 22.4%. Observed behavior reduces delay from 16.606 to 15.996 pedestrian-hours in the manual data and from 12.934 to 8.522 hours in video. Keywords: pedestrian counts, pedestrian actuation, Poisson arrivals, signal delay, noncompliance, traffic signals, SCATS, SydneyFigure 1.Probability densities and case ranges for MCAV count, MCAV delay assuming 100% compliance, and video count adjustments. The shaded band is the MCAV count interquartile range.
000
Reposted by David M Levinson ⁂
Sung Kim @sungkim.bsky.social · 21/08/2026
I should do this, going forward. 🤣
213420
David M Levinson ⁂ @transportist.org · 21/08/2026
ICYMI: Writing vs Editing, Abundance vs Scarcity, Creation vs Curation
dlvr.it
Writing vs Editing, Abundance vs Scarcity, Creation vs Curation
Michelangelo’s David (source Wikipedia) Writing and editing are, ideally, two stages in a complete creative process, yet we often prioritise the act of creation over the art of curation. The process of writing is mostly additive, with authors, starting with a blank page, spending the majority of their time on adding content rather than subtracting. This imbalance leads to verbose texts that obscure the core message, wasting the reader’s time.1 Drawing from the metaphor of Michelangelo’s David, where the sculptor’s task was to reveal the figure already in the marble, “geological processes” of creation are akin to the writer, while the editor, our Michelangelo, must refine and shape the existing material. Sadly, Geology gets no credit despite having created the marble, and thus David.2 Yet, this editorial role is often undervalued, despite clarifying and distilling ideas for the reader, saving the reader time, lowering their costs of idea acquisition, and increasing their net value. In the era of large language models (LLMs), which are inherently additive in nature, balancing creation with creative destruction is required to offset tools that flood the market with content quickly. LLMs are unmotivated to subtract,3 which is essential for clarity and impact. This shift from scarcity to abundance in content creation demands a renewed emphasis on curation. FIN.1 "This book should have been an essay. This essay should have been a blog post. This blog post should have been a tweet." — source unknown2 Some will credit God, but nevertheless geological forces were required3 In general, they are rewarded in training for more text rather than less. Read more
000
David M Levinson ⁂ @transportist.org · 19/08/2026
Writing vs Editing, Abundance vs Scarcity, Creation vs Curation Michelangelo’s David (source Wikipedia) Writing and editing are, ideally, two stages in a complete creative process, yet we often prioritise the act of creation over the art of curation. The process of writing is mostly additive, with…
transportist.org
Writing vs Editing, Abundance vs Scarcity, Creation vs Curation
Michelangelo’s David (source Wikipedia) Writing and editing are, ideally, two stages in a complete creative process, yet we often prioritise the act of creation over the art of curation. The process of writing is mostly additive, with authors, starting with a blank page, spending the majority of their time on adding content rather than subtracting. This imbalance leads to verbose texts that obscure the core message, wasting the reader’s time.
010
David M Levinson ⁂ @transportist.org · 19/08/2026
Writing vs Editing, Abundance vs Scarcity, Creation vs Curation
dlvr.it
Writing vs Editing, Abundance vs Scarcity, Creation vs Curation
Michelangelo’s David (source Wikipedia) Writing and editing are, ideally, two stages in a complete creative process, yet we often prioritise the act of creation over the art of curation. The process of writing is mostly additive, with authors, starting with a blank page, spending the majority of their time on adding content rather than subtracting. This imbalance leads to verbose texts that obscure the core message, wasting the reader’s time.1 Drawing from the metaphor of Michelangelo’s David, where the sculptor’s task was to reveal the figure already in the marble, “geological processes” of creation are akin to the writer, while the editor, our Michelangelo, must refine and shape the existing material. Sadly, Geology gets no credit despite having created the marble, and thus David.2 Yet, this editorial role is often undervalued, despite clarifying and distilling ideas for the reader, saving the reader time, lowering their costs of idea acquisition, and increasing their net value. In the era of large language models (LLMs), which are inherently additive in nature, balancing creation with creative destruction is required to offset tools that flood the market with content quickly. LLMs are unmotivated to subtract,3 which is essential for clarity and impact. This shift from scarcity to abundance in content creation demands a renewed emphasis on curation. FIN.1 "This book should have been an essay. This essay should have been a blog post. This blog post should have been a tweet." — source unknown2 Some will credit God, but nevertheless geological forces were required3 In general, they are rewarded in training for more text rather than less. Read more
000
David M Levinson ⁂ @transportist.org · 19/08/2026
ICYMI: Urban enshittification
dlvr.it
Urban enshittification
I promise I did not kick these bikes over. Text within this block will maintain its original spacing when publishedWhen there's an ad-wrapper on the bus you ride, so you can’t clearly see outside, that’s enshittification.Text within this block will maintain its original spacing when publishedWhen someone leaves a shared e-bike on the footpath you hike, that’s enshittification.Text within this block will maintain its original spacing when publishedWhen a billboard appears right where you walked freely for years, that’s enshittification.Text within this block will maintain its original spacing when publishedWhen the cycle runs so long the walkers stand till dawn, that’s enshittification.Text within this block will maintain its original spacing when publishedWhen a car’s tuned to roar so the whole block can hear even more, that’s enshittification.For example, here, is the problem that the council, which does not provide proper bike parking, or Lime, which refuses to enforce proper parking, or the bicyclist, who fails to park their bike in a reasonable place, about 1/2 block from actual bike parking at the train station down the hill? The 2024 word of the year, coined by Cory Doctorow,1 does not just describe internet platforms, it describes a lot of the erosion and destruction of the commons we face in urban environments, destruction at the hands of international corporations, local governments without much sense, state traffic engineers maximising vehicle throughput, or just your local neighbourhood assholes. This is why we have to have rules and regulations and laws backed by police with guns, because too many people are selfish jerks without either any concept that what they are doing is a problem, or not caring. Council officials who fail to do anything are complicit in the enshittification of the pedestrian realm. All of which is to say: Operations (which deals with today’s people moving on today’s network) is more important than Planning (which deals with a small increment of additional imaginary future people moving on imaginary future networks), and we spend relatively little effort on it. A bus safety campaign bus wrapper which reduces the visibility from inside the bus, discouraging people from taking the bus.Construction closes sidewalk, pedestrians told to cross street to other side, but walking in the street is highly dangerous and prohibited by law. How do I cross the street without walking on it. One giant leap for mankind I suppose.It’s Bin Day I guess. Must block the footpath not the taking space for storing cars.Funny how these advertising billboards don’t appear in the street, just the footpath.Someone missed the memo on what a “Shared” Zone is. FIN1 Ironically I suppose, I am linking to Amazon. Song lyrics due to: When the moon hits your eye Like a big pizza pie, that’s amore When the world seems to shine Like you’ve had too much wine, that’s amore — Dean Martin A police car and a screaming siren A pneumatic drill and ripped up concrete A baby wailing and stray dog howling The screech of brakes and lamp light blinking That’s entertainment That’s entertainment A smash of glass and a rumble of boots An electric train and a ripped up phone booth Paint splattered walls and the cry of a tomcat Lights going out and a kick in the balls I say, that’s entertainment That’s entertainment — Paul Weller and The Jam Read more
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David M Levinson ⁂ @transportist.org · 17/08/2026
Urban enshittification I promise I did not kick these bikes over. Text within this block will maintain its original spacing when published When there's an ad-wrapper on the bus you ride, so you can’t clearly see outside, that’s enshittification. Text within this block will maintain its original…
transportist.org
Urban enshittification
I promise I did not kick these bikes over. Text within this block will maintain its original spacing when published When there's an ad-wrapper on the bus you ride, so you can’t clearly see outside, that’s enshittification. Text within this block will maintain its original spacing when published When someone leaves a shared e-bike on the footpath you hike, that’s enshittification.
001
David M Levinson ⁂ @transportist.org · 17/08/2026
Urban enshittification
dlvr.it
Urban enshittification
I promise I did not kick these bikes over. Text within this block will maintain its original spacing when publishedWhen there's an ad-wrapper on the bus you ride, so you can’t clearly see outside, that’s enshittification.Text within this block will maintain its original spacing when publishedWhen someone leaves a shared e-bike on the footpath you hike, that’s enshittification.Text within this block will maintain its original spacing when publishedWhen a billboard appears right where you walked freely for years, that’s enshittification.Text within this block will maintain its original spacing when publishedWhen the cycle runs so long the walkers stand till dawn, that’s enshittification.Text within this block will maintain its original spacing when publishedWhen a car’s tuned to roar so the whole block can hear even more, that’s enshittification.For example, here, is the problem that the council, which does not provide proper bike parking, or Lime, which refuses to enforce proper parking, or the bicyclist, who fails to park their bike in a reasonable place, about 1/2 block from actual bike parking at the train station down the hill? The 2024 word of the year, coined by Cory Doctorow,1 does not just describe internet platforms, it describes a lot of the erosion and destruction of the commons we face in urban environments, destruction at the hands of international corporations, local governments without much sense, state traffic engineers maximising vehicle throughput, or just your local neighbourhood assholes. This is why we have to have rules and regulations and laws backed by police with guns, because too many people are selfish jerks without either any concept that what they are doing is a problem, or not caring. Council officials who fail to do anything are complicit in the enshittification of the pedestrian realm. All of which is to say: Operations (which deals with today’s people moving on today’s network) is more important than Planning (which deals with a small increment of additional imaginary future people moving on imaginary future networks), and we spend relatively little effort on it. A bus safety campaign bus wrapper which reduces the visibility from inside the bus, discouraging people from taking the bus.Construction closes sidewalk, pedestrians told to cross street to other side, but walking in the street is highly dangerous and prohibited by law. How do I cross the street without walking on it. One giant leap for mankind I suppose.It’s Bin Day I guess. Must block the footpath not the taking space for storing cars.Funny how these advertising billboards don’t appear in the street, just the footpath.Someone missed the memo on what a “Shared” Zone is. FIN1 Ironically I suppose, I am linking to Amazon. Song lyrics due to: When the moon hits your eye Like a big pizza pie, that’s amore When the world seems to shine Like you’ve had too much wine, that’s amore — Dean Martin A police car and a screaming siren A pneumatic drill and ripped up concrete A baby wailing and stray dog howling The screech of brakes and lamp light blinking That’s entertainment That’s entertainment A smash of glass and a rumble of boots An electric train and a ripped up phone booth Paint splattered walls and the cry of a tomcat Lights going out and a kick in the balls I say, that’s entertainment That’s entertainment — Paul Weller and The Jam Read more
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David M Levinson ⁂ @transportist.org · 16/08/2026
@Alon (they/them) do you all have data on how transport construction time frames vary over time and by location?
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David M Levinson ⁂ @transportist.org · 09/08/2026
No cookies needed fosstodon.org/@RockyC/1170593...
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David M Levinson ⁂ @transportist.org · 08/08/2026
Waymo involved fatal collision (causality TBD)
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