Transportist: November 2020

Transportist Posts


  • Davis, Blake, Ji, Ang,  Liu, Bichen, and Levinson, D. (2020) Moving Array Traffic ProbesFrontiers in Future Transportation. doi: 10.3389/ffutr.2020.602356 [doi]
  • Ji, Ang and Levinson, D. (2020) Injury severity prediction from two-vehicle crash mechanisms with machine learning and ensemble models. IEEE Open Journal of Intelligent Transportation Systems. [doi]

Book Chapters


You may have noticed that Transport Findings has become Findings. We believe the core idea of open access, peer-reviewed, short form research articles that is central to Findings has applications well beyond the transport domain, and we don’t want to limit ourselves (or you). We could have started a lot of small journals, but it is more cost effective, and probably also more beneficial, to keep everything under one journal name, with multiple sections and editors.

So everything we have published to date is in the section Transport Findings, as will undoubtedly be many future papers. But we are pleased to announce that we have opened up a new section Urban Findings, edited by Somwrita Sarkar, which will be launching soon. Urban Findings welcomes submissions following the Findings model of short, to-the-point research findings in the broad field of urbanism. You can see the Editorial Board here.

So at this time we are about Findings in the domains of Transport and Urbanism, because those are the practical limits of our current expertise, but we see no reason in principle that there should not be other sections.

If you have ideas about a topic area that you would both like to see articles for, and are willing to edit, please let us know. Editors of the new section would have to help recruit an editorial board, solicit articles, find reviewers, and, of course, make editorial decisions.

Unfortunately, we can only pay you in social capital, but those rewards are enormous, you will be helping assemble the knowledge of humanity, brick-by-brick, finding-by-finding.


  • Praharaj, Sarbeswar, David King, Christopher Pettit, and Elizabeth Wentz. 2020. “Using Aggregated Mobility Data to Measure the Effect of COVID-19 Polices on Mobility Changes in Sydney, London, Phoenix, and Pune.” Findings, October.
  • Toulouse, Catherine, Saeid Amiri, Marie-Soleil Cloutier, and Nicolas Saunier. 2020. “Speed Limit Changes and Driver Behaviour: A Spatial Lag Model.” Findings, October.
  • Adediji, Yemi, and Robert Noland. 2020. “How Data Imputation Affects Crash Modeling Results.” Findings, October.


  • The University of Sydney’s First Roderick Distinguished International Webinar is scheduled on Thursday, 19 November 2020, from 6-7pm (AEST) via Zoom. Prof. Jennifer Whyte from Imperial College London will talk on Infrastructure projects and digital delivery.  CLICK HERE to register. 
  • I will be speaking at the Festival of Urbanism on November 18. Mobility and Housing Futures: Lessons from COVID-19 and the 2019-20 bushfires. I will be talking about the “New New Normal: Mobility and Activity in the ‘After Times’”
  • I talked to the University of British Columbia on November 4 (their time) about “The New New Normal”.


Research by Others

News & Opinion


My solution for increasing Sydney real estate prices: A giant helium inflatable mirror ball tethered to a ferry and floating over Sydney Harbour so everyone has a view of the water.


Slightly Less F*cked

I had held this issue until after the November election, since there wasn’t much hope to get through the noise before the election.

posted to Twitter:

There are two choices on the ballot. If one of them wins, we will be collectively f*cked. What remains of democracy will be in tatters, along with all of the other problems society has. If the other wins, we will be slightly less f*cked. It’s highly unlikely they will solve most of the problems we have, but we will be slightly less bad off, democracy will get at least one more election cycle to restore itself, a semblance of an attempt to solve social and environmental problems will be made. It’s unlikely they will succeed, but they will at least defer the point of failure, slowing the rate of decline. Vote for slightly less f*cked.

Assuming Biden won, my general view is that the US, democracy, and the world are slightly less screwed than before the election, but there remain a huge set of long-term hurdles in front of us, none of which have been solved, all of which are solvable, all which on my happier days I hope we can solve, and most of which I expect won’t be solved, hence my general pessimism. 

We are taught that story-telling requires a triangle of victimvillain, and hero surrounding the problem. The technical problems are all laid out below. The meta-problem is that the victims, villains, and heroes are often an overlapping set of people. All of us in transport understand this as a social dilemma, when individual incentives don’t align with society’s. We see this with congestion, the marginal cost of delay a traveler imposes on others exceeds the cost of delay the traveler herself experiences.

In no particular order, and certainly not a complete list: 

  • Electoral reform is a particularly American problem, due to its historically early and constitution that is too difficult to amend. Some combination of compact districts (no gerrymandering), each district getting electoral votes (as per Maine and Nebraska), and ranked choice voting would be a huge, and easily implemented first step solution not requiring an Amendment (the states would need to consent, but federal $ are usually good for that). But there is far more to do to get this right. (Victim=democracy, representativeness; Villain=constitution, politicians through the ages who never fixed this, US Senate, residents of low population states) 
  • To this we can add:
    • judicial reform, 
    • voting reform, 
    • restoring voting rights for those returning to society, and numerous other related reforms. Somehow these things are not a problem in Australia, where everyone can (and indeed must) vote, there aren’t unnecessary lines, voter suppression isn’t a thing, prisoners are not prohibited from voting, they are required to vote, votes are counted quickly, you can vote for whomever you want without wasting your vote because of ranked choice voting, and people accept the outcome of the election, even if they are disappointed, because the process was perceived fair. The PM will not have a majority of votes nationally, because that’s not how it’s decided, he is elected by the majority party or coalition in Parliament and will only have won his/her own seat. The winning party may not have a majority of votes nationally either, it’s ranked choice voting, but they have won some number (usually a plurality) of seats, and can form a coalition. The system isn’t perfect, it still has a monarch – the Queen of Australia is on the money – it doesn’t really get the idea of consultation is to actually consider public input before making decisions not merely collect it and tick a box, it’s been described as electing a dictatorship that must go back to the people every 3 years for re-election, and has few checks on its power in the interim but for that election.
  • Civil rights and policing may be improving, but as we become more aware of the issue due to ubiquitous cameras it seems to be getting worse. But whether it is improving or not, the state of policing is bad, and the police violence in the US exceeds other countries. (Victim=those oppressed by police and in fear of police, Villain=police) None of this every was acceptable.
  • Gun violence in the US is almost completely solvable in a technical sense, examples of countries with much better records include Australia and New Zealand, but is not solved. (Victim=those killed, Villain=people with guns shooting people)
  • The virus, for which eventually we will get ‘herd immunity’ because everyone who has survived has had it, or an efficacious vaccine eventually arrives. In the mean time this of course has resulted in lockdowns, devastated industries including tourism, aviation, public transport, retail, restaurants, and entertainment. (Victim=everyone, Villain=virus)
  • The financial system, which has a of course huge amounts of inefficiency, fueled by debt, leading to bubbles in asset prices and stocks (the 5-year change in the S&P 500 is 64%, even considering the virus, does that sound like a reasonable increase in the expectations of future profits? … sure if interest rates go to zero, than NPV goes to infinity, but that doesn’t seem likely to me given all the other dynamics … at some point people lose confidence in the ability of governments to repay their ever-rising debts), as well as huge amounts of inequity, growing steadily worse over time. The Rise of Carry is an excellent if difficult book explaining some of the bubble dynamics. I have become something of a perma-bear, but that’s because I am highly suspicious of the Adderall-fueled frat boys running up the prices of stocks, not because I doubt capitalism and markets can do great things if properly regulated. (Victim= investors, people who participate in the economy; Villain=algorithms, people who write algorithms, Adderall, traders)
  • Pollution/decarbonisation, America’s response to COVID-19 portends poorly for any hope of an impactful ‘behavioural fix‘ for climate change. It’s ‘tech fix‘ or nothing. Behaviour and investment (in things like vehicle electrification and adoption of renewable power and phase out of fossil fuels) can of course be incentivised with prices, but while this has been known to be the correct policy for decades, it has hardly been implemented. Hopefully the prices of solar, wind, and batteries keep falling, so change will happen despite political recalcitrance. But there is no guarantee this tech fix is fast enough or complete enough to meaningfully minimise the continually increasing negative outcomes of climate change. At which point removing carbon from the atmosphere seems an increasingly likely solution (which would have been unnecessary had the carbon not been put there in the first place.) We still have problems with deforestation and loss of biodiversity that are also critical, getting back to the problem that no one owns the environment or is economically motivated to protect it. (Victim=environment, people who breathe, people who live near the ocean; Villain=polluters, people who use non-renewable electricity and fossil fuels)
  • Traffic safety, the US is killing pedestrians at an increasing rate (as described by Angie Schmitt), for reasons that are well known, and solvable (since many countries are improving on this metric) but for which society is unwilling to do anything. (Victim=people hit by cars, their family, friends, medical system; Villain=people who drive, people who make cars, people who make roads).
  • Congestion, which isn’t really as much of a problem these days, but we still refuse to solve it and insist on building 20th century infrastructure in response. (Victim=people who travel, people who subsidise roads; Villain=people who drive)
  • Critical Thinking Skills. Have we added lead back into the air? I ask this because people sure seem to be getting stupider and more vulnerable to conspiracy theories than before. Science, is a largely self-correcting system, but its influence on important issues has become needless politicised, especially, but not only, in the US (see: vaccines, pollution). Now this isn’t worse than some points in the past, Galileo had some issues I hear, but surely now that we live in the future, we should be more accepting of the scientific consensus. We have failed to educate non-scientists and non-engineers (both those with and without university educations) enough about how to think clearly, so all we get is muddle and conspiracy.
  • Government transparency. Compared to the US, this is particularly an Australian, and perhaps New South Wales, problem, but documents that should be public (e.g. business cases for massive public infrastructure projects) are held as “cabinet-in-confidence” for ages. Other data, like travel surveys, are not even made available to researchers under confidentiality agreements. What is being covered up? Surely not the thing I am requesting, but they can’t hold only the thing being covered up “in confidence”, otherwise we could figure out what it is. (Victim=citizens, good government; Villain=politicians and government staff)
  • Crony capitalism … as described in The Game of Mates by Cameron Murray and Paul Frijters … is a pervasive problem in government, along with the revolving door guaranteeing that politicians who do favours are rewarded in the “after life”. (Victim=taxpayers; Villain=politicians and crony capitalists)

Injury severity prediction from two-vehicle crash mechanisms with machine learning and ensemble models

  • Ji, Ang and Levinson, D. (2020) Injury severity prediction from two-vehicle crash mechanisms with machine learning and ensemble models. IEEE Open Journal of Intelligent Transportation Systems. [doi]

Machine learning algorithms aim to improve the power of predictors over conventional regression models. This study aims to tap the predictive potential of crash mechanism- related variables using ensemble machine learning models. The results demonstrate selected models can predict severity at a high level of accuracy. The stacking model with a linear blender is preferred for the designed ensemble combination. Most bagging, boosting, and stacking algorithms perform well, indicating en- semble models are capable of improving upon individual models.

The New New Normal: Mobility and Activity in the `After Times’

We may be nearing “peak city”. This shift undermines all of the place-based strategies that economic development organisations have been promoting for decades. It’s a topic David Levinson will be addressing at the Festival of Urbanism 13-26 November. This article was originally published in The Fifth Estate, November 2, 2020.

The Dot-Com boom and Y2K crisis compressed a decade of technological investment into a two-year period. As a bubble, it was naturally followed by a stock market crash, but the Internet is bigger and more important than before. Since Y2K we have seen the advent of smartphones (the Internet in our pocket), social media, Wikipedia, ride-hailing (mobility on demand in our pocket) and a major refactoring of many if not most businesses around the new information reality.

COVID-19 has initiated as profound a transformation, acculturating the population to videoconferencing and  work from home and virtual conferences and webinars and distance learning and online shopping (for everything) and remote medicine and  Zoom weddings and funerals and many other activities that once would have been experienced in person. This transformation did not begin from scratch, all of these changes had already begun, but they were accelerated by events.  The home has at least temporarily returned to its historic pre-urban role of being the restaurant, the workplace, the schoolhouse, the theatre — making it more crowded and more intense.

Eventually, like Y2K, COVID-19 will cease to be an issue and we will enter the `After Times’. The fear of others will dissipate but not disappear.  Its effects on society will linger. 

Many people who previously stood all day at a hot-desked, open plan, office in the CBD  have discovered they like working at home at least some of the time, so long as they also don’t need to supervise children.  Couple that with finding that 37% of all jobs in the US can be done entirely at home, 39% in Australia, a greater share of those in metro areas, and a greater share still in Central Business Districts. Many more jobs can be engaged with at least part-time at home. Thus, many firms  have discovered they don’t need to pay for expensive CBD real estate. Soon governments and universities will discover the same. Many shoppers and eaters like getting deliveries rather than going out, and distribution infrastructures have scaled up to enable this. Dark kitchens designing meals for delivery will ensure they are no longer mere allusions to tasty food.  Many students find they like attending class from home, which may be China, and now they are able to.

It’s not that some of the people don’t miss some of the ways of the `Before Times’ — commuting at least some times provides a spatial and mental separation between home and the workplace. In a study we conducted during the Sydney lockdown (Aoustin 2020), almost everyone was traveling less, and respondents were asked how they experienced the decrease in time spent in transport. On a scale of 1 to 7, 51% said they missed this time little or not at all, 17% were indifferent, but 32%  did miss it. Travel to work does not need to take place at 8:00 am five days a week, 50 weeks a year, packed into a shiny metal box.

This prospective future no doubt would come as a disappointment to Urban Triumphalists, who insist the value of cities is due to economies of agglomeration resulting from face-to-face interaction, as well as organisations like the Property Council. While historically in-person contact has driven economies of agglomeration, and why be in cities but to be near other people, the question remains: Must it always be so? Mega cities were largely non-existent in the pre-Industrial Revolution period when the economies of agglomeration were often outweighed by the diseconomies. Cities will not be abandoned quickly, transitions are long, but we may be nearing `peak city’. This shift undermines all of the place-based strategies that economic development organisations have been promoting for decades. 

Face-to-face encounters will remain important for a few sectors, those with high trust issues like politics, or requiring hands-on physical interactions, it is clearly being abstracted away. The risk we as a civilisation face is that of the explore/exploit trade-off – if the urban triumphalists are correct that new ideas emerge more from in-person interaction, while we can continue to exploit existing ideas, we will generate fewer of them and the rate of progress will slow. 

I am not convinced this is true, certainly not to the degree it once was. Perhaps more ideas can be generated from the vast increase of total interactions online, even if those interactions are intermediated electronically, than the serendipitous in-person encounters traditional place-based thinking privileges. This is not necessarily Zoom meetings, certainly not group meetings, but may instead be real-time (or nearly so) text-based interactions, bulletin boards, messaging, Slack, Twitter, Miro, and the like.

The implications of these changes on physical places are several. 

If more is to be done at home for more of the day, the demand for more space per person at home will increase, and the demand for person space in offices will diminish. While physical distancing requirements may remain at offices, giving those in the office building more space as well, it also drives up costs of offices, further inducing firms to increase their virtuality. The demand for new office construction will be permanently reduced, and we may see buildings or sites retrofit for other purposes, perhaps residential, as they run through their lifecycle. The demand for housing in contrast will tend toward the larger, with in-home offices for every member of the household becoming standard for those who can afford it. This of course drives houses to places where land is cheaper, the edge of the metropolitan sphere, or beyond, rather than the center, as the commute to the center, which may once have been daily, is now reduced to weekly. The challenge will be to make good suburbs and desirable small towns, where people can still engage in meaningful out-of-home activity, while accommodating their demands for larger structures.

Daily travel changes are already visible: though vehicle miles traveled in the US are largely back to normal (with more rural and less urban travel), public transport levels are not. It will be a while before, if ever, public transport returns to the pre-virus normal, even in places like Sydney which were not nearly as severely hit as China, the US, and Europe. Work-from-home, fear of exposure on public transport (and not just personal fear, official fear being promulgated by governments), and just a general economic downturn and unemployment are all factors to date.  

Substitutes like walking and biking (and especially the newly cost-effective e-biking) are likely to pick up some of the slack for those who continue to travel to work in the CBD, though more needs to be done to facilitate safe bicycling, in particular instituting a much larger network of separated and protected bike lanes. Even auto travel will change though, while total vehicle travel may remain stable or drop only a small amount compared with the Before Times, the nature of that travel differs so it is less peaked. This implies less demand for new road infrastructure, as the usage of roads is more balanced across the day. 

The After Times are post-post industrial. The industrial districts that were fashionably converted to urban office precincts will now get reconverted, perhaps to residential, which the market will always demand – people have to live somewhere, even if they can work anywhere.

If we will indeed interact primarily intermediated by the Internet, we will have finally moved to the next stage of human development, that of spaceless places. The flip side of spaceless places are placeless spaces. We will abandon spaces we no longer need. The CBD office building is the first target. New and expensive transport links to connect to the central city, or relieve peak congestion, will also be seen as white elephants.

Fig 4. Tract-to-Tract Commutes of 80km/50 miles or less in Minneapolis-St. Paul.
Fig 4. Tract-to-Tract Commutes of 80km/50 miles or less in Minneapolis-St. Paul.
Covid-19 virus. Source wikipedia
Covid-19 virus. Source wikipedia

Urban Infrastructure: Reflections For 2100

I have a chapter in

Urban Infrastructure: Reflections For 2100: An Edited Volume Imagining Infrastructure Transitions And Goals At End-Of-Century. Edited by Sybil Derrible and Mikhail Chester.

As you’d expect, my chapter is a bit on the snarkastic side. It begins something like this:

While digging for bitcoin in my copious Sydney backyard, I uncovered golden tablets revealing to me the near future history of transport in Sydney. …

Book Overview

Infrastructure systems deliver basic and critical services. They are the pillars of civilization. In the twenty-first century, infrastructure will need to change to fit the needs of a new world. What shape will they take? What function will they provide? Who will they serve and why? In this book, forty experts from around the world share their reflections for infrastructure at 2100. The book is a series of science fiction short stories, essays, and poems. Climate change, sustainability, resilience, and technology are recurring themes in the reflections. Written in 2020, it is impossible to predict how infrastructure will be in 2100. The goal of this book is not to make accurate descriptions of the future. Instead, it is to provide a dialogue and visions of what we could hope for or fear. Only time will tell on which side of the balance we end up leaning.

Moving Array Traffic Probes

Recently published:

  • Davis, Blake, Ji, Ang,  Liu, Bichen, and Levinson, D. (2020) Moving Array Traffic Probes. Frontiers in Future Transportation. doi: 10.3389/ffutr.2020.602356 [doi]

This paper explores the potential of moving array ‘probes’ to collect traffic data. This application simulates the prospect of mining environmental data on traffic conditions to present a cheap and potentially widespread source of traffic conditions. Based on three different simulations, we measure the magnitude and trends of probe error (comparing the probe’s `subjective’ or time-weighted perception with an `objective’ observer) in density, speed, and flow in order to validate the proposed model and compare the results with loop detectors. From these simulations, several conclusions were reached. A single probe’s error follows a double hump trend due to an interplay between the factors of traffic heterogeneity and shockwaves. Reduced visibility of the single probe does not proportionately increase the error. Multiple probes do not tend to increase accuracy significantly, which suggests that the data will be still useful even if probes are sparsely distributed. Finally, probes can measure the conditions of oncoming traffic more accurately than concurrent traffic. Further research is expected to consider more complex road networks and develop methods to improve the accuracy of moving array samples.

Keywords: Autonomous vehicles, Probes, Traffic state estimation, Floating car data, NetLogo