Post-Doc Wanted: Transport Networks at University of Sydney

I am recruiting a Post-Doc at the University of Sydney. The ad is below:

Postdoctoral Research Associate in Transport NetworksUsyd_new_logo

Faculty of Engineering and IT

School of Civil Engineering

Applications are invited for the appointment of one Postdoctoral Research Associate (Level A) in the School of Civil Engineering, within the Faculty of Engineering and IT at the University of Sydney.

The position will support the research and leadership of  School of Civil Engineering in the newly launched Transport Engineering program.

The successful applicant(s) will help build the new research group headed by Professor David Levinson to further the analysis of Transport Networks, understand the relationships between Transport Networks and Land Use, and consider the implications of changing Transport Technologies on optimal Network Structure.

Applicants should hold a PhD in civil engineering or a related field. They should be able to demonstrate high quality research in the area of transport networks, geo-spatial analysis, and econometrics. Demonstrated ability to publish research outcomes in high-quality international journals is also essential. Since the position will require frequent liaising with government and industry, applicants should demonstrate strong communication skills.

Please see the following link or contact me for details.

Link – Postdoctoral Research Associate in Transport Networks Ref 779/0417

Closing date: 11:30 pm 21 May 2017

Network Growth Research Wins Major Award

Sadly, it’s not my research on network growth that won a major award, the penalty of being a civil engineer and thus invisible to economics. But nevertheless congratulations to Stanford economist Dave Donaldson for winning the John Bates Clark medal for work in economic history, and better still, transport history, and even better still for examining network investment and Its consequences.


How large are the benefits of transportation infrastructure projects, and what explains these benefits? To shed new light on these questions, this paper uses archival data from colonial India to investigate the impact of India’s vast railroad network. Guided by four predictions from a general equilibrium trade model, I find that railroads: (1) decreased trade costs and interregional price gaps; (2) increased interregional and international trade; (3) increased real income levels; and (4), that a sufficient statistic for the effect of railroads on welfare in the model (an effect that is purely due to newly exploited gains from trade) accounts for virtually all of the observed reduced-form impact of railroads on real income in the data. I find no spurious effects from over 40,000 km of lines that were approved but – for four different reasons – were never built.

Hopefully this brings more attention to the subject, which is a vitally important, and bidirectional positive feedback system: the relevant question is not only how does transport affect the economy (Donaldson’s question, as it has been of many before), but also the complementary mutual causality question of how does the economy (including land use) affect the construction of transport. Too bad (according to the NBER version of his paper) he was unaware of the great and long-standing literature in transport geography and regional science, and more recent literature in physics and network science. This starts perhaps with Bill Garrison (as all things do):

  • Garrison, W. L., Berry, B. J. L., Marble, D. F., Nystuen, J. D., & Morrill, R. L. (1969). Studies of highway development and geographic change. Greenwood Press.
  • Garrison, W.L., and Marble, D.F. (1965). “A prolegomenon to the forecasting of transportation development.” Office of Technical Services, United States Department of Commerce, United States Army Aviation Material Labs Technical Report.

See a summary of the literature to 2005 (and it’s probably time for a new synthesis, PhD candidates) in this 2005 paper:

  • Levinson, David (2005) The Evolution of Transport Networks,
    Chapter 11 ( pp 175-188) in Handbook 6: Transport Strategy, Policy and Institutions (David Hensher, ed.) Elsevier, Oxford

Obviously it’s an area I have been researching (with both empirical and simulation methods) for a number of years, hopefully making what I think are useful scientific contributions. For some more recent examples, my 2008 paper Density and Dispersion and the papers collected in 2011’s Evolving Transportation Networks by Feng Xie and myself from his MS Thesis and Dissertation, among others. Other of my publications, including the work of Feng Xie,  on the subject are listed at the bottom of this post. I will also note a couple of Special Issues that I edited on the subject:

Network Growth, My Contributions

The development of transportation networks is a function of policy, planning, and engineering decisions, the inherent geographical and topological structure of networks, and traveler preferences dictating how the network is used. Research into Network Growth aims to disentangle these phenomena, and by doing so, understand the implications of present decisions on future options.

My first major contribution was the discovery of the self-organizing nature of the hierarchy of roads. Some roads are more important (carry more traffic at higher speeds) than others (e.g. major highways vs. local streets). Current design guidelines suggest how a road hierarchy should be laid out by highway planners. However, even in the absence of planners, using a new agent-based simulation model describing the actions of travelers and investment in the network, the interaction of travel behavior (travelers seeking the shortest time path) and simple feedback rules (resources being spent to improve links in proportion to traffic) will produce a hierarchy of roads very similar to what is observed in practice, even if roads start from an undifferentiated state aside from their spatial position (Yerra and Levinson 2005, Levinson and Yerra 2006). We showed that network structure (and the network growth rules) can affect network reliability (Zhang and Levinson 2008), an overly hierarchical structure had serious reliability problems, while the grid network had better efficiency performance, as well as error and attack tolerance.

The second major contribution was the establishment from empirical findings that transportation and land use co-evolve: certain transportation investments are positively and significantly related to future land development, and that land development is positively and significantly related to subsequent transportation investment. Using data compiled from the UK census and the historical development of the surface and underground railway systems in London, a 17 decade time series for 33 boroughs of London was used to rigorously test the hypotheses (Levinson 2008a), which corroborates earlier findings based on five decades of highway and land use data in the Twin Cities (Levinson and Chen 2006). This positive feedback system is convergent, and as systems mature (e.g. the transportation network is built out) its subsequent effects are steadily weaker.

The third major contribution from this research is demonstration using analytical models that governance is endogenous to the transportation technology investment process. As transportation networks get faster (either through investment using existing technologies, or through development of faster new technologies), the amount of inter-jurisdictional traffic increases, and these positive spillovers create demand for higher levels of government (state v. county, e.g.) to manage transportation funding. (Xie and Levinson 2009 “Governance Choice on a Serial Network”). This comports with the historical evidence that transportation has become increasingly dependent on higher levels of government for funding as longer distance (e.g. interstate) travel takes a large share of the total. These three contributions are detailed in the book Evolving Transportation Networks (Xie and Levinson 2011)


References for my work on network growth and evolution, and its causes and consequences.

I know, these are specialist field journals, not Nature and Science, and so get little visibility. But they should all surface in a search of Google Scholar with little difficulty. We of course were unaware of his more recent work, which was in NBER, and will be buried in the obscure economics literature (Supposedly it’s forthcoming in AER, some podunk field journal in some social science sub-discipline). There is a vast chasm between fields.

On Megaregions

Jeff Hargarten wrote: Welcome to Laurentide — the Twin Cities as a mega-region: A map created by university researchers reveals the Twin Cities to be the center of its own universe of commuters  in the StarTribune.

So Megaregions are back as a topic.

Just as there is more economic activity and commuting within cities than between cities, and within metropolitan areas than between metropolitan areas, there is more activity within megaregions than between them. So there is some advantage to thinking about megaregions as a territory over which some economic and transport decisions should be made. It should not be the dominant framework (as local travel and economic activity within a metropolitan area is much greater than the trade between such areas).

But for intercity travel, it might make sense to think of nearby metropolitan areas as interacting. And as historically transport was increasingly faster over time, the area of daily interaction steadily expanded. In the city of the 1800s, when people traveled at walking speeds, cities were much smaller than they became first with the streetcar, and then with the automobile. Even now, in the Northeast corridor, there are a reasonable number of people who regularly commute between nearby cities (Philadelphia to New York, Baltimore to Washington), and a smaller number who commute longer distances (Washington to New York), usually on a less-than-daily basis, but often enough.

While transport had gotten faster over time, though recently it seems to have stagnated. Some people view high-speed rail  (very fast trains) as the next logical step. I think the Internet is the next step, which leads to a more global community with worldwide interactions, rather than HSR. It depends very much on the context, but in most of the US, HSR doesn’t pencil out in a market where it competes with other modes at anywhere near their current costs.  Autonomous Vehicles will emerge as well, and inevitably lead to people who own such vehicles being willing to travel longer distances, as it will lower the costs of travel (since people will not need to engage in the driving task and can do other things with their time in motion).

The key planning problem I think is that land use decisions are made very locally (at the township or municipality level), while important transport decisions are made at the regional or state level. Yet land use decisions generate demand for streets and highways outside of the local jurisdiction that permitted them, while transport decisions affect local governments. Clearly local governments are not keen to let metropolitan areas make land use decisions, or even have veto powers, and similarly cannot be responsible for regional transport decisions.

The Metropolitan Council is an unusual Metropolitan Planning Organization (MPO) as it has some operational responsibilities in transit and water and wastewater, as well as in distribution of grants. Existing planning organizations have enough difficulties executing their existing mandate, it is hard to imagine them growing. They may become members of Megaregional Organizations. It is not clear what role a Megaregion Organization would have beyond advocacy. Would it have any responsibilities for actual infrastructure? MPOs that cross state lines are notoriously difficult.

If we properly priced things like pollution and congestion and access to public facilities, this suburbanization and exurbanization would be less of a problem, but we give away the right to travel on the roads at any time of day regardless of how many people you congest, we give away the right to pollute the air (with some regulation, but hardly enough), and we subsidize public works like water treatment, sewer, local streets, schools, and parks for new development.

It is also not clear if the Twin Cities is truly part of a Megaregion with any other large metropolitan areas (Duluth, St. Cloud, and Rochester don’t count), it is pretty far from Chicago (compared with say Milwaukee or Indianapolis). Maybe it is just a “region”. Clearly the region will continue to expand into the exurbs, particularly as the habit of “going to work” changes from something done daily to something done weekly for many people as the ability to work at home for some tasks continues to grow. Traveling an hour once or twice a week is less onerous than traveling a half-an-hour daily.  On the study that was cited in the Hargarten article, see . I have some issues with the methods and assumptions about the daily commutes of supercommuters as drawn from ACS data.

My quotes from the article:

“There really are these kinds of natural regions. I think this is the way in which the economy is working,” said Tom Fisher, a University of Minnesota professor and director of the Minnesota Design Center. “It’s also part of the conversation about how the global economy rests on cities.”

As a caveat, David Levinson, a professor of transport at the University of Sydney, points out that mega-commuters – defined by the Census as those traveling 90 or more minutes and 50 or more miles to work – and others making similarly long journeys don’t necessarily make those commutes daily, and not always from their home city.

But Levinson said there are advantages to considering mega-regions as targets for central planning around economic and transportation decisions, though it shouldn’t be the primary framework for such discussions.

Some of those challenges involve the development of physical connections between cities, by way of roads, high-speed transit and other means. Experts also cited political polarization and a lack of cohesive regional planning as particularly strong barriers standing in the way of regional development.

Levinson said that although transportation has historically sped up over time, it’s stagnated recently. To him, digital commuting via the internet may emerge as the next logical step to further tighten economic bonds across cities. Self-driving vehicles, too, could take some of the pressure off drivers and allow them to travel longer distances while also engaging in other tasks.

“The 20th century version [of regional competition] has Minneapolis competing against St. Paul. But in the 21st century the competition has to be with other regions. Otherwise we’ll be less successful globally,” Fisher said.

De-Duplicating Sydney’s City Road

City Road (A36) is a 1 km road segment in Sydney, part of the much longer “Princes Highway“, that extends King Street (the heart of the Newtown Neighborhood) to Broadway (which is renamed Parramatta Road just to the west) (map).

King Street is a lively (dare I say the “v”-word, vibrant), narrow-ish (though still wide in places) active street with retail and restaurants fronting both sides, and people traveling back and forth. As a newcomer, King Street strikes me as a combination of Telegraph Avenue in Berkeley (on steroids) plus Portobello Road in London’s Notting Hill.  In contradistinction, City Road is a much wider car sewer, bi-secting the University of Sydney, which has a footbridge (pedestrian overpass) to keep the kids from playing in traffic. It once had a tram (streetcar) that continued from the City through Broadway on to King Street.

At some point (I would guess the 1950s, but perhaps as late as the 1970s) City Road was duplicated (i.e. widened with a median dividing the road). This allows traffic to go a bit faster before they are stopped at the same traffic lights that undoubtedly existed previously, and saving very little, if any travel time. (The queues at the lights might be shorter (fewer cars deep) and wider (i.e. more lanes), so there is possibly some time savings at the junctions, thus possibly reducing the likelihood of stopping, but it can’t be very much).

Screenshot 2017-04-18 09.05.03
City Road (in Blue) would be de-duplicated. New apartments (Red) would use the former right-of-way and line Victoria Park. Drawing is schematic and not-to-scale.

So my idea (this doesn’t even rise to the level of proposal) is to reduce City Road from 6-8 lanes back to 2-4 travel lanes (i.e. just use one side of the Median (I would say the southern side), plus right turn (the equivalent of left turn where people drive on the right side of the street) lanes as needed, and develop in the right-of-way on the northern side. Some right-of-way (two lanes worth) could be preserved for a future transitway (buses or trams) as well. This would slow traffic, but be more fitting for an urban road in the heart of a major university.

The opportunity to develop is particular apt at Victoria Park, just to the east of the University, where new, valuable apartments, lining the now narrowed City Road, with park views could be constructed without taking park lands or casting much shade on the park. These apartments would have very good access to the University and the Sydney CBD by walking and transit respectively, and would instead of generating traffic, likely reduce it (as if you live closer to your destination you are more likely to not have or use a car, and this would substitute for housing farther away).

I am sure there are a thousand reasons this can’t be done, and I am new here and naive. Maybe someone has already proposed this. I don’t have clue about the institutional issues.

However, bigger picture, the future with the gains from efficiency of vehicle automation is fewer lanes and narrower roads. Demographers forecast a huge expansion of the population of Sydney and the enrollment in the University set to rise. This site seems a perfect match.


On lying as a vicious cycle

Back in 2008, as the world economy was on the verge of collapse, I wrote a post “Trust as a positive externality.” At the time the concern was whether people would continue to redeem little green pieces of paper for actual goods and services. Fortunately, wise leaders stepped up to the occasion, and while their actions were imperfect and too few bankers went to jail, the system of trust that drives the economy of civilization was maintained.

We have recently decided as a civilization to elect unwise ‘leaders.’ ‘Leaders’ for whom the old joke:

“How can you tell when a politician is lying?

They are moving their lips”

is no longer funny.

If we cannot trust the word of our so-called ‘leaders,’ can we trust their minions, or anyone in government who reports to them and does their bidding. And as lying becomes the norm, won’t the entire system of trust will break down? Why should one cooperate with the dishonest? And if you cannot tell who remains honest, or no-one remains honest, mutually beneficial cooperation, the cornerstone of civilized society, crumbles.

Ensuring trust, that someone will do what they say (i.e. pay you) after you do what you say (perform a service) is tricky, but extremely valuable. The value arises in being able to trade with strangers, not just brothers and cousins. It permits specialization in a way unfathomable to Adam Smith.

To enable the smooth function of trust, society developed an entire legal system to avoid cycles of vigilante vendettas that arose after perceived or real slights. But as liars take the helm, the legal system itself becomes corruptible. We have a chain where at one end are the judges, appointed over time by the liars. In the middle are prosecutors, typically appointed by the same, and at the other end are the police, with their own biases.

So if I loan you money, and you don’t repay, and I sue you, but you control the courts, or just have friends in the right places, I will not get repaid. If I know that, I won’t loan you money. Instead, if I am not careful, you will just take my assets, and I will call the police, and they will shrug their shoulders, and I have lost my money anyway. Smart people outside the power structure will try to emigrate from such a low trust society, leaving it with a brain drain and less voluntary trade, less specialization, so ultimately it will under-perform higher trust societies over time. This is bad on dimensions beyond the economic.

Trust can decay from the bottom up or the top down. The disintegration is surely faster when it starts at the top.

The Royal Easter Show

Sydney’s Royal Easter Show runs for 12 days in (southern hemisphere) Fall, round-about Easter, hence the name. In 2015, 769,000 people attended the show, which lasts 12 days. I went on Easter Sunday with some colleagues from work, as I like the idea of State Fairs (I like the idea much more than I actually like the Fairs themselves).

My main point of comparison is the Minnesota State Fair, reportedly one of the three largest and best fairs in the US (vs. Iowa and Texas), though I have only been to fairs in a few others places (Maryland and Arizona, both of which it clearly beats).

Objectively, the Minnesota Fair is larger than the Easter Show, with nearly 2 million attendees over 12 days. It didn’t seem like there were more people at Minnesota’s Fair than Sydney’s, so I suspected the density is the same, and Minnesota’s fair covers more space, and this was just observation bias. This turns out to be the case: Minnesota’s 320 acres (129.5 ha) is three times larger than Sydney 45 hectares (111 acres). In fact, if we hold the 12 days fixed, 1.9M/129 ha = 14,728 persons/ha  vs. 769,000/45=17,089 persons/ha, Sydney’s Show is actually slightly denser, like the city as a whole.

Getting there is surprisingly simple. The Easter Show is well served by direct express trains from the city (and other locations with transfers) to the modern Olympic Park station where it is held. The trains stop right outside the front gate, and are free to showgoers. The frequency was fairly high, and the trains were crowded by the time I left in the afternoon, so that staff was doing crowd control measures. (The crowd probably could have self-regulated at the time I left, but staff was there anticipating large crowds, so probably felt the need to make themselves useful. I suspect later in the day, their measures would be useful).

Olympic Park has many other events (some 5000) throughout the year, notably sports (ANZ Stadium, the Olympic Stadium hosts four forms of professional football: Rugby League, Rugby Union, Association Football (soccer), and Australian Rules Football, as well as cricket) and much of the Olympic Park grounds are not part of the Showgrounds.

The entry fee is a high $41 for a single adult, though there are small discounts if you purchase in advance. To be clear this is Australian dollars, but this is still far more expensive than Minnesota, even with paid parking.

The Easter Show had the usual gamut of Fair Food ranging from corn dogs on a stick (which were better than Poncho or Pronto Pups), to a decent gelato, and a truly awful pot pie about which the only nice thing I can say is that it did not make me ill. There were fewer food vendors overall than Minnesota, yet more higher end and ethnic food at the Royal Easter Show. The logic perhaps being ‘in for a dime in for a dollar.’  And they foods were more expensive for comparables (while in general, restaurants in Sydney are not especially more expensive than Minnesota after controlling for the dollar, quality, and quantity). I was disappointed not to see more authentic Australian country food, it seemed a lot more American style than I expected. Of course to the Australian, perhaps the American is more exotic. A bottle of water was $3.50 from the vending machine, but $4.00 from the vendors themselves. Note: bring your own water.

There were also the same types of fun fair amusements and rides, but many fewer of them. And they were more expensive.

There were the animal barns, of which the emphasis on Alpaca was the most notably different from what one sees in Minnesota. They were bigger on Equestrian Events as well.

We watched Wood-chopping competition. Basically how much wood could a wood-chopper chop if a wood-chopper could chop wood? Can they split the tree-trunk section in 22 chops, beating the previous chopper? It’s better than it sounds, and it has its own arena, and is crowded, and has contestants from 6 countries (AU, NZ, US, CA, ES, and Wales).

Sydney is big on the “Show Bags”, an expensive bag with an assortment of related things, most typically cheap children’s toys with some cartoon character brand, a $10 value for the low low price of $24. It’s basically a shake-down of the parents.

I also enjoyed the fishing lure display (selling another Show Bag), where the fisherman/promoter was on top of the tractor of the tractor-trailer, and the trailer was a giant glass aquarium filled with water and fish. He would demonstrate his lures by casting his line into the water, and you could see the (undoubtedly hungry) fish follow the lure. He didn’t have a hook on his line, so he wouldn’t injure his co-stars.

Transport for New South Wales had a mockup of their now under construction Metro line, along with a VR display of the tunneling machine breakthrough.

While there was some antique farm machinery around, there was as far as I could tell no equivalent to machinery hill.

The Minnesota State Fairgrounds is located adjacent to the Saint Paul campus of the University of Minnesota, and has been there for decades. The Royal Easter Show is now at the Olympic Park. So it is reusing (or sharing) a number of more modern facilities that opened for the 2000 Olympics (it actually moved in 1998 according to the history). There were fewer specialty buildings than Minnesota, and the buildings likely get used for more non-fair events throughout the year. Yet there were some buildings likely without much alternative uses.

Overall it’s more modernist feel makes it more like a convention than fair. The best architecture at the Minnesota Fair is from the New Deal period. There is nothing old at Sydney. This of course means the air conditioning works.  I have not seen the pre-2000 Showgrounds, so I am not clear the state they were in at the time, and I am sure from a lot of perspectives this is an upgrade, it just has a more urban feel, with so much paved over in concrete, which isn’t quite what I expect from a fair. To be clear there were droppings near the various farm animal and horse exhibits, so nature wills out, and the smell of the fair is ensured.

Richard P. Braun

I am sad to read that: Former MnDOT Commissioner Richard Braun has died at 91. I held the RP Braun/ CTS Chair  in Transportation at the University of Minnesota for 10 years, so in a sense I bore his name, repeating his every time I introduced myself.

Honestly, I didn’t really know him that well at a personal level, we met at CTS events, but the times we met he was both charming and sharp, as well as straight-forward and supportive.  While his demeanor was genial, funny, and good-natured, he was also someone for whom no wool would cover his eyes. He was one of the few people whom everyone that I respected, respected. My sense (and the obituary article reiterates this) is the biggest call of his time leading MnDOT was closing the St. Paul High Bridge for safety reasons. I think too many people are afraid to make hard decisions, and the short-term expediency of keeping each and every road rolling takes too high a priority.

I will note that I was also given the Braun Distinguished Service Award by CTS a few years ago (which is normally given to faculty nearer retirement, so I took it as a hint).

Measuring the transportation needs of people with developmental disabilities: A means to social inclusion (free version)

“Measuring the transportation needs of people with developmental disabilities: A means to social inclusion” is now available online. The “free” link provides free access, and is valid until May 31, 2017

Recently published:



One of the major causes of social exclusion for people with developmental disability (PDD) is the inability to access different activities due to inadequate transportation services.


This research paper identifies transportation needs, and reasons for unmet, but desired untaken trips of adults with developmental disabilities in Hennepin County, Minnesota. We hypothesize that PDD cannot make trips they want to make due to personal and neighborhood characteristics.


A survey measuring existing travel behavior and unmet transportation needs of PDD (N=114) was conducted. The survey included both demographic and attitudinal questions as well as a travel diary to record both actual and desired but untaken trips. Logistic regression analyses were conducted to determine reasons associated with their inability to make desired, but untaken trips.


Most respondents did not live independently. More than half of the surveyed population worked every day and recreation trips occurred at least once a week for about two-thirds of the population. About 46 percent were unable to make trips they needed to make. Public transit posed physical and intellectual difficulties, however the presence of public transit in neighborhoods decreased odds of not making trips. Concerns about Paratransit services were also reported.


Findings from this study can be of value to transportation engineers and planners interested in shedding light on the needs of a marginalized group that is rarely studied and have special transport needs that should be met to ensure their social inclusion in society.


I am pleased to report I am safely in Australia and gainfully employed by the University of Sydney.

Bureaucracy slayed. Achievement unlocked.