Measuring polycentricity via network flows, spatial interaction, and percolation

Recent working paper:

Polycentricity is most commonly measured by location-based metrics (e.g. employment density or total number of workers, above a threshold, used to count the number of centres). While these metrics are good indicators of location ‘centricity’, the results are sensitive to threshold-choice. We consider here the alternate idea that a centre’s status depends on which other locations it is con- nected to in terms of trip inflows and outflows: this is inherently a network rather than a location idea. A set of flow and network-based centricity metrics for measuring metropolitan area poly- centricity using Journey-To-Work (JTW) data are presented: (a) trip-based, (b) density-based, and, (c) accessibility-based. Using these measures, polycentricity is computed and rank-centricity distributions are plotted to test whether these distributions follow Zipf-like or Chirstaller-like distributions. Further, a percolation theory framework is proposed for the full origin-destination (OD) matrix, where trip flows are used as a thresholding parameter to count the number of sub-centres. It is found that trip flows prove to be an effective measure to count and hierarchically organise metropolitan area sub-centres, and provide one way of dealing with the arbitrariness of defining a threshold on numbers of employed persons, employment density, or centricities to count sub-centres. These measures demonstrated on data from the Greater Sydney region show that the trip flow-based threshold and network centricities help to characterize polycentricity more robustly than the traditional number or density-based thresholds alone and provide unexpected insights into the connections between land use, transport, and urban structure.SankeyFlowsSydney

Sport in Australia: A Primer for Americans

Sport is a big deal in Australia (and it is usually Sport, not Sports)*. In schools, there is both a PE class and a Sport class.*

In this country of 25 million people, there are many sport leagues and franchises, maybe more per capita than minor league sports in the US, and thus more similar to college or even high school sports.

This weekend alone are the world championships for the AFL (The Australian Football League Grand Final) and the NRL (National Rugby League  [Telephone Company sponsored] Premiership Grand Final).*

AFL is popular in Melbourne and the western parts of Australia, NRL in New South Wales and Queensland. The maps of professional teams are shown below, and are visible examples of the process of spatial diffusion of competing ideas (in this case, competing footy codes).

AFL Teams (via Wikipedia)
AFL Teams (via Wikipedia)
NRL Teams (via Wikipedia)
NRL Teams (via Wikipedia)

The rules are too complex to explain here, but feel confident that they have a family resemblance to American-rules football, but all have evolved from the proto-ball sport in different directions. AFL is more soccer like (but players can touch the ball and punch it, but kicking remains important, serving the role of the forward pass and punt) and played on a cricket oval.

In contrast NRL is more like American football without a forward pass, and played on a rectangle. NRL has downs, but no such things a first down, the team scores or turns over the ball. AFL players are leaner and taller, NRL players are stockier. Neither use helmets. AFL is probably safer. I believe the expression is: the NRL is a ruffian’s game played by gentlemen, the AFL is a gentlemen’s game played by ruffians.*[update in the footnote]  The balls themselves are similar.

In the NRL, the most important event during the season is the State of Origin series, which is an all-star like event where the best players from Queensland play against the best players from New South Wales. This is a 3-game series. AFL once had a similar event.

The AFL Championship (broadcast on the Seven network) this year is the Collingwood Magpies vs. the West Coast Eagles, played at the southern hemisphere’s largest stadium, the Melbourne Cricket Ground (MCG), where the championship has been played almost every year since 1902.

Where the hell is Collingwood? It’s a neighbourhood of Melbourne. Where is the West Coast? Somewhere on the Indian Ocean I suppose. Why does a Melbourne neighborhood get a team in the national championship, while an entire coast of the only known inhabited planet’s third largest ocean get another? Something looks gerrymandered. The AFL used to be (in living memory) the Victoria Football League (VFL) and it grew out of club sport serving highly localized fanbases, much like Baseball (the Brooklyn Dodgers), Basketball (the Fort Wayne Pistons), and Football (the Camden Bulldogs) in the US. The NFL still has a team in Green Bay, recalling its roots. The whole system is more reminiscent of Premier League with its many teams in London.

Collingwood’s uniform resembles that of a US referee, or prisoners in old-timey striped outfits. Much worse than the Yankees pinstripes. The Eagles are much more modern, with the distraction of a Hungry Jack logo in the corner.*  In the event the Eagles won this year 79 – 74 in an exciting match that saw them come-from-behind in the last few minutes.

The key thing about Australians is that they love the idea of being in love with sport more than they actually love sport. This is not to say there are not Australian sport fans, there obviously are, and ABC Radio reports more on sport than America’s NPR, but the reality of sport fandom is not so different than/from/to the US.

Sport faces the same pressures as in the US, the coverage, the TV shows about the wives of ballers, the advertising, the concern about the player whose sister who loved playing herself died tragically two weeks earlier, it’s the same but relabeled.

I have heard some promote the terrible idea that Australian unis should have college sport the way US schools do to promote something (school loyalty, alumni donations, more corruption). While US college sports does promote those things (relative to Australia’s relative indifference), it’s an historical anachronism due to their arrival before professional sport. Australia is nothing if not oversaturated in sport. So even if such clubs could be established, I am not clear they would get anything resembling American college fanbases. However today, sport at the uni level is basically at the intramural level, and on the level of Middle School sport in the US.

So these championship games don’t necessarily sell out the arena in which they are paid. Regular season games seldom sell out. Part of this is hurt by teams playing in large metropolitan stadia. NRL teams in Sydney often play in Sydney’s large Olympic Stadium named after a financial company with the letters A and N and Z in its name, or a different stadium in Moore Park named after a different financial company with  A and N and Z in its name. Nevertheless there are plans to remodel the first and replace the second stadium. This is of course unnecessary.

These final games are nevertheless Superbowl-like spectacles; the Black Eyed Peas (sans Fergie) were one of the opening acts for the AFL game, they have previously done a SuperBowl (in 2011).

The NRL Premiership (on the Nine Network’s Wide World of Sports) is the following day (Sunday). There is also a women’s game, and a junior game, earlier in the day, but the stands are mostly empty for these matches.

In 2018 it’s the long awaited match between The Sydney Roosters vs. The Melbourne Storm. As you can tell, the Roosters, by their nickname, are an old club, and the Storm are much newer, when abstract nicknames gained popularity. The Storm are appearing in their third consecutive Grand Final.

The pre-game show has much guitar and fireworks and smoke, but its mostly cleared by game time. The athletes are standing for Advance Australia Fair, but of course Australian police officers don’t kill nearly as many Australians as US officers. Sport is probably the most racially integrated sector of Australia, now struggling with appropriate recognition of First Australians, well behind Canada and New Zealand in this regard, but arguably ahead of the US at this point.

The Roosters are sponsored by Steggles — which due to the cursive font at first I thought was Steagles, like the World War II mashup of the NFL’s Philadelphia Eagles and Pittsburgh Steelers. Steggles sells frozen chicken. So it’s a bit auto-phagic or cannibalistic to be sponsored by a company that will eat you and your kind. The Storm are sponsored by Crown Casino. The Refs are sponsored by Youi, which is an insurance company.

Most NRL teams were historically in greater Sydney, and the Roosters were based in the wealthy Eastern Suburbs (think Bondi), but the league has expanded to have teams in other Oceania cities (including one in New Zealand and 3 in Queensland (costing Sydney some franchises, but in this 16 team league there remain 9 Sydney area teams.

A quick guide for Americans. NRL is basically like American-rules football except: Scoring in NRL: Field Goal = drop goal = 1 point, a touchdown = a try = 4 points.  The extra point conversion kick is worth 2 points, and is kicked from the edge of the field, and there are no blockers. This is also a 2 point penalty kick. When you score the other team kicks off to you. There is one set of 5 downs. There are a lot of punts on the 5th down, though teams seem more likely to go for it, and turn the ball over if they don’t score a try, sometimes they just go for a 2 point kick (but there are no special teams for this, this is in continuous play, unlike the 2 point conversion and penalty kicks). Punts are a combination of punt and forward pass (in that a team can recover its own punt, but there is no actual forward pass, all passes are lateral and backwards (like the end-of-game play the American-rules football team behind sometimes does). The offensive and defensive players are the same. There is no quarterback or other specialist players, though some players are of course more significant than others. There are no helmets, but there are similar concussion issues. There are no huddles or timeouts (except official timeouts and instant replay reviews). There are nevertheless fumbles and interceptions and other kinds of turnovers. It’s a continuous flow game, and lasts 80 minutes of actual activity. The players wear shorts and short sleeve shirts. There are scrums when control of the ball is disputed somehow. The penalty box is called the Sin Bin.

In short, it’s a superior game that could become popular in the US, except for the lack of the forward pass, but I don’t know how it could be elegantly incorporated.

In the event the Sydney Roosters defeated the Melbourne Storm 21-6, a game the Roosters dominated from the beginning.

After this weekend’s sportgasm, Monday is a holiday, Labour Day in NSW, ACT (Canberra), and South Australia, but Queens Birthday in Queensland*, and the beginning of the two week Spring Break for schools in NSW. Holidays are not standardised across Australia, the states are much more nation-like.

This survey would be incomplete without mentioning that there is also Cricket (in a few distinct formats as people are less keen on 5 day matches than they once were), basketball (the NBL), netball, A-League soccer (which is growing, but not yet dominant), and the ponies.


  • While it is “Sport” not “Sports”, note that it is “Maths”, not “Math”. Why? Because.
  •  In addition to  Sport and PE, public primary schools also have  two lunch/recess periods, and an opt-out religion indoctrination course, so the curriculum is perhaps not as academically rigorous as it might be.
  • Rugby League is not to be confused with Rugby Union.
  • I have been informed by an Australian that “In fact it applies to the difference between Rugby Union and Rugby League, the latter being a break way from Rugby Union which occurred in the north of England in 1895. The differentiation was that Rugby teams in the north comprised more working class men – coalminers etc – whereas in the south it was played by amateurs who had probably gone to one of the rugby football playing Public (read private) Schools. That tradition continues in Sydney with the so called Great Public Schools being strictly rugby union playing and historically Rugby league being played more by, for example the poorer Catholic schools. Certainly League is still more associated with the so called working classes if there is such a class any more.In fact the first rugby union club to be established in Australia was Sydney University’s in 1864 and the first match was in 1869 against my other alma mater Newington College.

    So in fact it is Rugby Union that is the ruffians game played by gentlemen – and that fact was certainly undeniable –  and Rugby league is, well, a ruffian’s game played by, well, ruffians! It was Football or Soccer that was termed a Gentleman’s Game played by ruffians (or thugs).

    AFL started as winter game to keep cricket players fit and is a complete mystery to anyone who grew up north of the Murrumbidgee River! It is unclear whether it is played by ruffians or gentlemen – possibly both! Certainly it is incredibly tribal in Melbourne – if you work down there you have to have a team or face being an outcast from any water cooler conversations, maybe any conversations, from about April to October.”

  • Hungry Jacks is Australia’s Burger King, though it tastes slightly better for some reason. In general Australian burgers are adulterated with items that are not ground beef, but the chains (like Macca’s and HJ) seems to avoid that problem. It is also also worth noting that a ‘burger’ is any kind of sandwich with cooked meat (so chickenburgers (chicken fillets) and lambburgers are common.
  • The Queen’s Birthday Holiday is not actually the Queen’s Birthday, and is celebrated on different days in different states.
  • I should also note somewhere that the  Herald Sun  (in Melbourne, owned by Newscorp) where the Grand Final of the AFL is front page news, is not the same as the Sun Herald (in Sydney, owned by Fairfax) where the NRL Premiership garners headlines, if things weren’t confusing enough.

Eleven Sydney council areas where pedestrians die more than motorists

Nigel Gladstone in the Sydney Morning Herald wrote “Eleven Sydney council areas where pedestrians die more than motorists“. I got some choice quotes:

Professor of transport at the University of Sydney David Levinson said changing the way Sydney’s traffic signals give priority to cars over pedestrians in busy areas was one way to stem the flow of injuries.

“This inequality [in traffic light phasing] undermines many of the stated goals of transport, health and environment policy,” Professor Levinson said. “Creating an environment that is better for pedestrians with separated footpaths, easy and frequent safe road crossings, generally slower cars and trucks, better trained and more law-abiding drivers (via police enforcement) will reduce the likelihood of fatalities.”

Road deaths have been increasing in both NSW and the US recently, while most other OECD nations are reporting fewer fatalities.

One theory [Referring to: Chi, Guangqing, Jeremy Porter, Arthur Cosby and David Levinson (2013) The Impact of Gasoline Price Changes on Traffic Safety: a Time Geography ExplanationJournal of Transport Geography 28 1-11. [doi] ] is that as more people can afford to be on the road, drivers with less experience, who tend to be younger, and therefore more dangerous, are added to the mix of motorists.

“When there’s economic expansion, people are working more hours and they probably get a bit more aggressive,” Professor Levinson said.

Research [by Wes Marshall] comparing Australian and American drivers found the rate of fatalities was more than twice as high in the US, where more than half of drivers do not stop or yield to pedestrians at crossings.

In Hawaii’s capital Honolulu, fines for pedestrians who text while crossing the road at traffic lights began this year.

In the City of Sydney, one in three people crossing the road is using a mobile phone and it’s time pedestrians “start owning this problem as well”, Pedestrian Council chief executive Harold Scruby said.

“Pedestrian deaths and serious injuries are going through the roof,” Mr Scruby said. “There is nothing that we’re seeing that the government is doing to help pedestrians.”

Hitting pedestrians with a $200 fine for using a mobile phone while crossing the road, even on the green man phase, is on Mr Scruby’s agenda.

“There’s no barrier there just because the light’s green. Half of the drivers coming towards you are on the phone too,” Mr Scruby said. “If you’re hit as a pedestrian, the driver will be automatically drug and breath tested but that’s a box they [police] have to tick, no one then goes looking for the mobile phone, there’s no box to tick.”

Professor Levinson said fining pedestrians was “basically a form of victim blaming”.

“Distracted pedestrians don’t kill drivers or passengers. Distracted drivers kill pedestrians,” he said. “Deaths are due to high speed and high mass, and drivers of two-tonne machines have an obligation to be more alert.”

In the three years to 2017, one pedestrian was killed and 25 were seriously injured while distracted by a mobile phone. But this is likely to be an under-reported issue, as it relies on witnesses telling police and other forms of evidence.

There are no plans to introduce penalties for people using mobile phones while crossing roads in NSW, a Transport for NSW spokesman said.


I also got to be ABC Radio Illawarra Friday Morning (talking about traffic safety), and ABC Radio Adelaide Friday Afternoon (talking about Beg Buttons) (first few minutes of this).

Dockless in Sydney: The Rise and Decline of Bikesharing in Australia.

Recent working paper:

Percentage of static bikes in Pyrmont by company and day (Bikes unmoved for 48h or more)

In mid-2017, dockless, (or stationless) bikesharing appeared on the streets of Sydney. The birth of dockless bikesharing, its evolution as well as its consequences, and use habits are studied with review of policies and field investigations. It is found that bicycle use in Sydney is less than hoped for, vandalism is high, regulations unfavourable, and thus, the conditions for successful bikesharing are not met.

When pushing the pedestrian button works and when it doesn’t | SMH

Nigel Gladstone of The Sydney Morning Herald answers: When pushing the pedestrian button works and when it doesn’t.

(The answer is it doesn’t work in the CBD during the day).

My quote:

Monetizing the beg button

Professor David Levinson from the School of Civil Engineering at the University of Sydney said traffic signals in the city should be shifted to be more pedestrian friendly to encourage more walking.

“Traffic signals give priority to motor vehicles over pedestrians. This inequality undermines many of the stated goals of transport, health and environment policy,” Professor Levinson said.

“Sydney uses adaptive signals so that they’re designed to maximise the throughput for cars and so they’ll extend the green light for cars but that results in there being more ‘don’t walk’ time for pedestrians.”

Comments on Sydney’s Cycling Strategy and Action Plan 2018-2030

Sydney has released its Cycling Strategy and Action Plan for public comment. Mine are below:


I am pleased to see Sydney hopes to be a more bicycle friendly place. However the plan as laid out is insufficiently ambitious. So much more can and should be done. Sydney should be one of the world leaders in bicycling, but it remains a laggard, stuck in the mid-20th century.  A 10% target in 2030 (3-4x as many bicyclists as today) is good (better than today’s baseline), but the network doesn’t support that, it is not 3-4x as large. 

To start, think about the network: Every major street (say a street that warrants a traffic signals) which also has on-street parking has demonstrated space for separated bike lanes.  What is more important, storing cars 23 hours a day or moving people? The value of the network increases non-linearly with its connectivity. Even most streets without on-street parking have space for bike lanes. 

Among these which I am familiar with should be included Regent St/Gibbons St/Wyndham St and Abercrombie/Wattle, but there are undoubtedly more. The separated bike lane network should be as dense and complete as the arterial street network.*

Similarly, every block that has on-street parking should dedicate at least one parking space to bicycle parking, particularly for shared bikes. Action 1.5 is especially lagging. Bike parking is cheap to install and signals priorities and should lead rather than follow. 

Bikesharing is neglected from this plan.

Regulation is still hostile to bicyclists, including heavy fines and futile helmet laws. Helmets are indicator of danger. Biking should be normalised as in Europe.

A strategy for promoting and regulating eBikes would be good. Also promoting and regulating scooters, skateboards, and other wheeled vehicles (micro-mobility).

A strategy for promoting bike and ride to train and metro stations would be good.

A strategy for promoting biking to school (and Uni) would be good. Schools are at least mentioned, but it seems mostly an afterthought.

Bikes should be counted continuously at intersections (not just 2 times a year), just as cars are. There are technologies to do this, and RMS can be called on to do it. Electronic signs displaying bike counts on key routes is also a good marketing tool.



*Note: The base map p. 17 locates the Metro stations in the wrong place. The map does not distinguish between shared paths and separated bike lanes, which is a way of claiming credit for something that doesn’t actually exist.

The Street: Design for People

I will be appearing at The Street: Design for People August 9 at 12:30 at the Powerhouse. Tickets via Eventbrite (not free, sadly). This is organized by Foreground, who published my piece on The Future of the Footpath.

A panel of experts examine how the burgeoning urban pressures of the 21st century are affecting how we design and occupy our streets, at a public forum on 9 August at the Powerhouse Museum, Sydney.

Streets are essential for transporting both people and goods, but they are much more than just thoroughfares. They have their own intrinsic value, serving myriad civic functions, from social interactions to commercial exchange, and from cultural expression to political debate. They are also constantly changing.

For the past month, Foreground has been running a special series examining the street, from green streets that work as a hedge against the effects of climate change, to the effects of changing traffic and mobility patterns on street parking, safety and shared usage, and how encroaching privatisation is challenging its legacy as a civic commons.

As the culmination of this special series, Foreground is convening a public forum of experts with a professional interest in the street to examine how this critical piece of infrastructure might address the burgeoning urban pressures of the 21st century.


Professor David Levinson teaches at the School of Civil Engineering at the University of Sydney, where he leads the Network Design Lab and the Transport Engineering group He is the author of the influential blog The Transportist, and is also an advisor to Sidewalk Labs spinoff Coord, which recently launched a data integration platform for urban mobility.

Dr Nicole Kalms is a founding director of the XYX Lab at Monash University, which leads national research in space, gender and communication. Her recent book Hypersexual City (Routledge 2017) examines sexualized representation in neoliberal cities.

Libby Gallagher is a registered landscape architect with over 20 years of professional experience on a range of public, mixed use and private projects in Australia and overseas. Recent award-winning projects include the Quality of Landscape Study for the City of Sydney and the Cool Streets Pilot Project for Blacktown Council.

Andrew Mackenzie (moderator) is a co-founder and co-editor of Foreground. Andrew has been a writer, curator, editor and publisher on art, design and architecture for over 20 years. He writes for various journals and newspapers and is a co-director at Uro Publications, and independent Australian publisher of books on architecture and design.

Why is Public Transport Use Higher in Australia than America and What to Do About It.

Why does Australia have higher transit use than the US?

This question has two major explanations: Driving is harder and using transit is easier. On the road side, as my colleague Wes Marshall says: “Policy-related differences include stronger and more extensive enforcement programs [in Australia], restrictive licensing programs, and higher driving costs.”

Transit Growth in Australia via
Transit Growth in Australia via

In places like central Sydney, narrower lanes and expensive parking also make driving a burden. The Australian motorway system is less developed than the US interstate highway system, though the government is funding major new urban motorways in Australia (e.g. WestConnex in Sydney).

Transit benefits because higher population and employment density (especially around transit stations ) within cities compared to  most US cities (as well as a more urban population overall) reduces access time to and from transit and enables higher frequency service to serve the demand. The train, bus, and tram systems in Australian cities are relatively high frequency and fairly reliable, with all-day service. While the systems are imperfect (as any daily commuter will tell you) they are orders of magnitude better than most of the US.

Transit service is a positive feedback system (The Mohring Effect, named for Transport Economist Herb Mohring who first identified it). More demand calls for more service, the additional service is in the form of additional buses and trains running at different times than the original service, reducing schedule delay, making transit more convenient, calling for more service. This works two ways, so transit cutbacks increase headways (decrease frequency) making transit less convenient, lowering demand, resulting in more cutbacks.

From the 1920s when tram (streetcar) use peaked (notably excepting the spike during World War II) through the 1960s there was a process of Bustitution — substitution of buses for trams. Many cities around the world (notably excepting places like Melbourne, Toronto, San Francisco, and especially selected cities in Europe) instead of paying the costs of recapitalising their tram systems, opted to convert tram lines to buses that had much lower capital costs.

In the US, there is a grand conspiracy theory, about how this came about. While most of the conspiracy theory is over-blown, there was some evil doing, as is the wont of people infected with greed (better known as people). In Minneapolis the people who converted the streetcar to buses went to jail, not for the conversion but for crimes like bribing state legislators and giving kickbacks. In Brisbane, the Paddington tram depot caught (were set) on fire as bus conversion was being debated, answering the question.

In general, the reality is much more market-rational. Electric trams were first deployed in the late 1880s, so by 1950 the service was over 60 years old. Trams needed a major capital infusion to keep operating. That capital infusion was not forthcoming from fares; in the US trams had clearly been in decline for the better part of thirty years.  It was a hard call for cities not to replace their trams with buses. The private sector, which financed trams initially, were unwilling to finance it again, leaving it to local governments to come up with money for the trams (or not, as it turned out).

So most cities became tramless. Those cities were losing transit riders before the conversion and lost more after the conversion. It’s a vicious cycle.

The new Light Rail mode (See Appendix) in North America kicked off with Edmonton (1978), San Diego (1981),  and Portland (1986). In retrospect, many people regret the process of bustitution, and cities that later reinstalled LRT systems would with perfect foresight likely have kept their tram lines going and recapitalised them. Note that the actual coverage of these new system is much smaller than the historical trams, most tram lines were removed in most North American cites, as in Sydney.

Wikipedia reports the farebox recovery is lower in Australia than US cities, which implies a higher public subsidy. (I am not convinced there aren’t methodological differences in accounting here, but it is worth noting).

Why is Australia’s transit use rising when the US is falling?

A train that showed up at Sydney’s Central Station

The second question is more difficult. One response is that fuel prices remain higher in Australia. Another is that there has been more investment in transit, including more frequent service and continuous improvements to stations and vehicles. Third, Australian cities have recently rolled out smart cards (Opal in NSW) like the Oyster Card in London, and along with it pricing reforms to reduce the fare penalty for transfers, which has significantly boosted use of transit.

Australia does some other things differently from the US. Among them is increased use of contracting out to private firms to provide service. (This is not universal yet, but is growing.) This is also done in the UK and most of Europe, but not very much in the US. This has effects on costs and perception and unionization. The contractors are for-profit businesses aligned with the idea of higher ridership, so support for transit in Australia is bipartisan, while in the US, transit is considered a Democrat issue in most places, and Republicans are often actively hostile as it is not their constituents (or only support transit to their suburban districts with high cost, low value commuter rail systems like Northstar in Minnesota).JtW-AU-Delta

While transit in the US is perpetually in “crisis” (to listen to its supporters), in Australia (and Canada and Europe) it is a normal part of society that is widely used, and doesn’t have the same stigma associated with it.

What should the public sector do to increase ridership?

I asked on Twitter “Would restoring Sydney Trams to a network resembling that at their maximum extent (291 km), similar in scope to Melbourne’s Tram network today, be a good use of public resources?”

The response was

  • 50% Yes, Benefits >> Costs
  • 27% No, Benefits << Costs
  • 23% Maybe, Benefits ~= Costs

Looking at Sydney the densities are much higher here than in most North American cites, aside from New York, San Francisco, Chicago. I previously examined the existing and planned trams in Sydney.

Because they are widely used, they have a strong constituency for their betterment, and government is responsive in expanding the system.

Convincing existing some-time riders to ride more is far easier than going from 0 to 1 as Peter Thiel might say.

I think early ridership gains come from going deep rather than going wide. A large fraction of the US still lives in areas designed around transit (basically pre-1920 America), including city cores and streetcar and commuter rail suburbs.  Residents sometimes use transit now. These places are much easier to serve because the land use in conducive to transit, the densities are high enough and the networks are oriented for transit access and service.

Good, relatively cost-effective service like Minnesota’s arterial BRT (bus rapid transit ) (MetroTransit’s A Line, eg) have shown large ridership and user satisfaction gains with low investment. The system is made more efficient with things like payment before boarding, and all-door boarding, reducing time at stops and increasing driver and bus productivity.

The aim should be to serve users better, not help non-users by reducing congestion, which may be a happy byproduct, any more than building roads aims to reduce transit crowding.


  • Wesley E. Marshall (2018) “Understanding international road safety disparities: Why is Australia so much safer than the United States?”
    Accident Analysis and Prevention 111. 251–265
  • Mohring, H.(1972). “Optimization and Scale Economies in Urban Bus Transportation,” American Economic Review, 591-604.

Appendix: Streetcars and Trams vs. LRT

The difference between Light Rail and older streetcars or trams is primarily, but not entirely, one of branding. Anyone who says there is a clear formal difference that people abide hasn’t gotten out much. Different cities use the same words to mean different things. Still there are differences in degree:

  • Streetcars or trams often share right-of-way in the street, while Light Rail often has a mostly exclusive right-of-way with at-grade crossings, but either system can be operated either way.
  • Light Rail vehicles tend to be wider with higher capacity and longer with higher capacity,  its longer vehicle is a heavier vehicle: Light Rail is not light, it’s only light with respect to commuter trains; it’s not light with respect to buses, cars, or people. Light sounds airy and like it should be less expensive, but it’s a only a little less expensive.

Transit vehicles and services form a continuum, you can operate streetcars in exclusive tunnels as in Boston. Both LRT and streetcars differ from commuter trains but it’s a continuum in regard to that as well.

Are Australian Vehicles Getting Bigger?

ABC Radio Sydney called me and asked essentially:

`Are Australian Cars Getting Bigger?’

The short answer is ‘No.’


Using data from the Federal Chamber of Automotive Industries that was once freely available online, and is now behind a paywall, I have produced graphs illustrating the Australian vehicle market.  The data show among the passenger cars: medium, small, light, and micro are all gaining in proportion of passenger cars, rising from half the passenger car market to 83% since 2000.


`Are Australian Vehicles Getting Bigger?’

The answer here is ‘Yes.’

As will be no surprise to Australians, or North Americans (See Canada data), the share of Sports Utility Vehicles has exploded since the beginning of the Millennium from about 13% to 39%, and now more SUVs are sold each year than passenger cars.



This trend, which mirrors that in the US, helps explain Ford’s recent decision to exit most of the passenger car business in the US.

Now 50%  of 70% is 35% (small cars share of all vehicles in 2000) while 80% of 38% is 30% (small cars share of all vehicles in 2017), so the share of small and medium cars of all vehicles is falling. But the total market of vehicles sold in Australia is still increasing from 787,000 in 2000 to 1,189,116 in 2017, and 30% of cars sold in 2017 is more than 35% of cars sold in 2000, so there are still more in terms of total number of small and medium cars sold in 2017 in total than 2000, even if it is a declining share of the market.

The Australian government also conducts a Motor Vehicle Census and just as the number of new cars sold each year rises with population growth, the total number of vehicles is also rising. This differs from the US, which has more or less peaked in cars per capita, and perhaps cars. I graphed this data for NSW for selected years (this data, is also, inconveniently, not in one place)


The reason for more SUVs vs. large cars are speculative. That is, why do people now prefer SUVs and not station wagons or big cars? It’s not as if people actually do a lot of off-road driving.

One is the idea of the extreme trip. Sometimes (say once a year or even once a month) a very large car would be useful. So instead of renting the specific vehicle when they want it, SUV-owners buy the vehicle they would use 1% of the their trips (or 0.05% of their time – since cars are only used 5% of the day anyway, and at rest the remainder, sleeping more than even cats), but which is too large 99.95% of the time.

One answer is the car Arms Race. In a taller car, the driver can see farther ahead (drivers are less likely to have their view obscured), which lets tall vehicle drivers anticipate better. It makes drivers feel safer, which they are for themselves, even when they are not for others.

More people are killed because of SUVs and light trucks, in the US, Michelle White estimated in 2004 “For each 1 million light trucks that replace cars, between 34 and 93 additional car occupants, pedestrians, bicyclists, or motorcyclists are killed per year, and the value of the lives lost is between $242 and $652 million per year.” Presumably the same logic holds in Australia.

Increasing the mass of vehicles on the road doesn’t do society any favours from an energy consumption, or air pollution perspective either. And of course, larger vehicles use more space, consuming more land in parking lots (which are now often restriped to accommodate more massive vehicles) and roads, where the width of lane consumed by larger cars rises, providing less manoeuvrability for other cars.

With the rise of autonomous vehicles, and especially vehicle sharing, the right sized vehicle will be summonable by app, so when travelers need the specific type of car for a large trip with many people, they can get it. The rest of the time, drivers will be able to use a car fit for purpose, one that holds one person for a one-person trip, and two people for two-person trips, and so on. This opens up the potential for skinny cars, enclosed electric cycles, and many other appropriate vehicles, which take up less road space, making it even easier to improve the environment for other road users, including walkers and bicyclists.

Toyota iRoad one-passenger concept cars, image courtesy Toyota.
Toyota iRoad one-passenger concept cars, image courtesy Toyota.


Passenger Motor Vehicles Passenger vehicles are classified dependent on size, specification and average retail pricing. Selected vehicle types will be assessed on footprint defined as length (mm) x width (mm), rounded, as follows:
Sports Utility Vehicles Vehicles classified as Sport Utility Vehicles (SUV) meet the FCAI criteria for classifying SUV vehicles based on a 2/4 door wagon body style and elevated ride height. Vehicles typically will feature some form of 4WD or AWD, however, where a 2WD variant of a model is available it will be included in the appropriate segment to that model.
Light Trucks Vehicles designed principally for commercial but may include designs intended for non-commercial applications.
Heavy Trucks Vehicles designed for exclusive heavy commercial application.

Car sizes:

Micro Hatch, sedan or wagon with a footprint < 6,300
Light Hatch, sedan or wagon with a footprint range 6,301 – 7,500
Small Hatch, sedan or wagon with a footprint range 7,501 – 8,300
Medium Hatch, sedan or wagon with a footprint range 8,301 – 9,000
Large Hatch, sedan or wagon with a footprint range 9,001 – 9,500
Upper Large Hatch, sedan or wagon with a footprint range 9,501 >
People Movers Wagon for passenger usage, seating capacity > 5 people
Sports Car, coupe, convertible or roadster

SUV Sizes:

Light Duty 3,501 – 8,000kg GVM
Medium Duty => 8,001kg GVM & GCM < 39,001
Heavy Duty 8,001kg GVM & GCM > 39,000

Light Truck Sizes:

Light bus < 20 Seats 8+ seats, but less than 20 seats
Light Bus > 20 Seats 20+ seats
Vans/CC <= 2.5t Blind/Window vans and Cab Chassis <= 2.5t GVM
Vans/CC > 2.5–3.5t Blind/Window vans and Cab Chassis between 205 and 3.5 tonnes GVM
Pick-up / Chassis 4×2 Two driven wheels, normal control (bonnet), utility, cab chassis, one and a half cab and crew cab
Pick-up / Chassis 4×4  Four driven wheels, normal control (bonnet), utility, cab chassis, one and a half cab and crew cab

Heavy Truck Sizes:

Light Duty 3,501 – 8,000kg GVM
Medium Duty => 8,001kg GVM & GCM < 39,001
Heavy Duty 8,001kg GVM & GCM > 39,000