26 May 2011 – FAVOURITES: Peter Newman and Jeff Kenworthy of Curtin University’s Sustainability Policy Institute in Perth, Western Australia, say a new phenomenon is under way –  “peak car use”.*

Peak car use suggests that we are witnessing the end of building cities around cars – at least in the developed world.

In the 1980s we called this kind of city building automobile dependence (Newman and Kenworthy, 1989).

The peak car use phenomenon suggests we may now be witnessing the demise of automobile dependence in cities.

The Global Cities Database (Kenworthy and Laube, 2001; Kenworthy et al 1999) has been expanding its global reach since the first data was collected in the 1970s.

While the 2005/2010 data are yet to be complete the first signs of a decline in car use can be gleaned from previous data and were first recognised by us in Newman and Kenworthy (1999) and Kenworthy and Laube (1999) when it was seen that cities in the developed world grew in car use per capita in the 1960s by 42 per cent, in the 1970s by 26 per cent and the 1980s by 23 per cent.

Our new data now shows that the period 1995-2005 had a growth in car use per capita of just 5.1 per cent.

In the 26 cities that comprise the 1995-2005 percentage increase in car vehicle kilometers travelled per capita, we are beginning to see some cities that have actually declined.

Some European cities show this pattern: London has declined 1.2 per cent, Stockholm 3.7 per cent, Vienna 7.6 per cent and Zurich 4.7 per cent.

In the US, Atlanta went down 10.1 per cent, Houston 15.2 per cent, (both from extraordinarily high levels of car use in 1995), Los Angeles declined 2.0 per cent and San Francisco 4.8 per cent.

Peak car use appears to be happening. It is a major historical discontinuity that was largely unpredicted by most urban professionals and academics. So what is causing this to occur?

Possible causes of peak car use

The following six factors are examined and then their overlaps and interdependencies are explored afterwards:

1.      Hitting the Marchetti wall

2.      Growth of public transport

3.      Reversal of urban sprawl

4.      Aging of cities

5.      Growth of a culture of urbanism

6.      Rise in fuel prices

Increase in public transport since 1999

1. Hitting the Marchetti wall

Thomas Marchetti was the first to recognise that all cities have a similar average travel time budget of around one hour (Marchetti, 1994). This seems to be biologically based in humans – they don’t like to take more out of their day than an hour just getting to their work and back home. Thus we have applied this to the technology of city building (Newman and Kenworthy, 1999) to show that cities always hit the wall when they are “one hour wide”.

A walking city is based around people walking at an average of 5-8 kilometres hour  thus in one hour people can walk 5-8 km; therefore a walking city can expand to 5-8 km wide before it becomes dysfunctional to go any further.

A transit city based on an average speed of 30 km/h for trains can extend to 30 km wide.

An automobile city based on an average speed of 50 km/h in cars can reach out to 50 km wide before the average travel time will be more than is acceptable to most people.

As cities have filled with cars the limit to the spread of the city has become more and more apparent with the politics of road rage becoming a bigger part of everyday life and many people just choosing to live closer in.

Fast trains have been the only technology to break this car-based limit, though they are limited in their origins and destinations in cities built around cars and soon hit the wall also.

The travel time budget limit is observable in most Australian and US cities where the politics of transport has been based on the inability of getting sufficient road capacity to enable the travel time budget to be maintained under one hour.

Thus there has been a shift to providing faster and higher capacity public transport based on the growing demand to go around traffic-filled corridors or to service growing inner area districts.

At the same time the politics of planning in the past decade has turned irrevocably to enabling greater redevelopment and regeneration of suburbs at higher densities closer in to where most destinations are located. The automobile city seems to have hit the wall.

Recent strong growth in US transit use and declining car use

2. Growth of public transport

The global cities data currently being updated show that in ten major US cities from 1995 to 2005 transit boardings grew 12 per cent from 60 to 67 per capita, five Canadian cities grew eight per cent from 140 to 151, four Australian capital cities rose six per cent from 90 to 96 boardings per capita, while four major European cities grew from 380 to 447 boardings per capita or 18 per cent

The growth in transit was always seen by transport planners as a small part of the transport task and that car use growth would continue unabated.

However, the exponential relationship between car use and public transport use indicates how significant the impact of transit can be. By increasing transit per capita the use of cars per capita is predicted to go down exponentially.

This is the so-called “transit leverage” effect (Neff, 1996; Newman et al, 2008). Thus even small increases in transit can begin to put a large dent in car use growth and eventually will cause it to peak and decline.

3. Reversal of urban sprawl

The turning back in of cities leads to increases in density rather than the continuing declines that have characterized the growth phase of automobile cities in the past 50 years. The data on density suggest that the peak in decline has occurred and cities are now coming back in faster than they are going out.

Table 1, below,  contains data on a sample of cities in Australia, the USA, Canada and Europe showing urban densities from 1960 to 2005 which clearly demonstrate this turning point in the more highly automobile-dependent cities.

In the small sample of European cities, densities are still declining due to “shrinkage” or absolute reductions in population, but the data clearly show the rate of decline in urban density slowing down and almost stabilising as re-urbanisation occurs.

Cities1960 Urban density



Urban density



Urban density



Urban density



Urban density



Urban density


Los Angeles22.325.024.423.924.127.6
New York22.522.619.819.218.019.2
San Diego11.712.110.813.114.514.6
San Francisco16.516.915.516.020.519.8

4. Aging of cities

Cities in the developed world are all aging in the sense that the average age of people living in the cities has been getting older.  People who are older tend to drive less. Cities therefore that are aging are likely to show less car use. This is likely to be a factor but the fact that all American and Australian cities began declining around 2004 suggests there were other factors at work than just aging as not all cities in these places are aging at similar rates.  The younger cities of Brisbane and Perth in Australia still peaked in 2004.

5. Growth of a culture of urbanism

One of the reasons that older aged cities drive less is that older people move back into cities from the suburbs – the so-called “empty nester” syndrome. This was largely not predicted at the height of the automobile city growth phase nor was it seen that the children growing up in the suburbs would begin flocking back into the cities rather than continuing the life of car dependence (Leinberger, 2007).

This has now been underway for over a decade and the data presented by the Brookings Institution suggest that it is a major contributor to the peak car use phenomenon (Puentes and Tomer, 2009).

They suggest this is not a fashion but a structural change based on the opportunities that are provided by greater urbanism. The cultural change associated with this urbanism is reflected in the “Friends” TV series compared to the “Father Knows Best” suburban TV series of the earlier generation. The shift in attitudes to car dependence is also apparent in Australia (Newman and Newman, 2006).

6. Rise in fuel prices

The vulnerability of outer suburbs to increasing fuel prices was noted in the first fuel crisis in 1973-4 and in all subsequent fuel crisis periods when fuel price volatility was clearly reflected in real estate values (Fels and Munson, 1974; Romanos, 1978).

The return to “normal” after each crisis led many commentators to believe that the link between fuel and urban form may not be as dramatic as first presented by people like us (Newman and Kenworthy, 1989; 1999).  However the impact of $140 a barrel oil on real estate in the US dramatically led to the global financial crisis (sub-prime mortgagees were unable to pay their mortgages when fuel prices tripled).

Despite global recession the 21st century has been faced by a consolidation of fuel prices at the upper end of those experienced in the last 50 years of automobile city growth.  Most oil commentators including oil companies now admit to the end of the era of cheap oil, even if not fully accepting the peak oil phenomenon (Newman, Beatley and Boyer, 2009).

The elasticities associated with fuel price are obviously going to contribute to reducing car use growth though few economists would have suggested these price increases were enough to cause peak car use that set in well before the 2008 peak of $140 a barrel.

Interdependencies in six factors

It is not hard to see that the six factors involved in understanding peak car use are all interwoven and interdependent and can result in multiplicative effects that are greater than the sum of the individual parts.  For example:

  • The Brookings Institution suggests that the growing price of oil may have been a substantive factor in pushing the trend to reduce cars, though the other structural factors around the culture of urbanism were also pulling the trend along.
  • The reurbanisation of car-based cities and the reorientation of transport priorities around transit, walking and cycling, are policies that feed on each other; once one begins the other tends to follow and together they can set in motion exponential declines in car use.
  • The motivation to move to a more urban location with less car dependence can be a combination of time saved in the travel time budget, fuel saved, a preference for urbanism and even getting older.

The urban planning profession has been developing alternative plans for automobile cities in the past few decades with the rationale of reducing car dependence involving all of the above factors; few however would have thought they would be quite so successful, perhaps because each of the factors had such interactivity and reinforcing effects.

Implications for peak car use

The reality of declining car use in cities will have big impacts on the professions. The trends suggest they are very different to how they have been trained and how their manuals suggest they should work. Some examples follow.

Traffic engineers will need to fundamentally change their traffic models and their assumption that increasing road capacity is their main raison d’etre.

The rationale for roads will shift away from accommodating cars to being much more inclusive of other modes – light rail, buses, cycling and walking. Road diets and traffic calming will become the skill they need to lead with rather than being pushed into.

In cases where road capacity has been reduced such as in the demolition of six kilometres of high capacity freeway through the centre of Seoul to create an urban stream and boulevarde, average speed across the city actually improved and there were no adverse traffic impacts (www.design-e2.com – Seoul: Stream of Consciousness).

This and other similar road diet projects that have been implemented around the world with similar experiences (Schiller et al, 2010), must lead to a change in how the traffic engineering profession conceives traffic, not as a “liquid” that will flow over everything if space is removed, but as a “gas” that compresses according to the space constraints imposed on it.

Peak car use will generate a growing rationale for removal of high capacity roads and conversion of space to support transit, walking and cycling and the urbanism of the new city.

Town planners will need to become much more adept at re-urbanising suburbs and centres than in scattering suburbs around the urban fringe (Newton, 2010)

The provision of reduced parking will be a tool that can help revitalise urban development. The reduction in road space will now be seen as a positive value for any new development.

The automobile city planning norm of minimum parking and maximum density will be reversed to maximum parking and minimum density to suit the new realities.

Urban design of the public realm will become a much more critical factor in urban development as it has over many years in the extensive redevelopment and especially transit-oriented development that has shaped cities like Vancouver since the late 1970s.

Urban financiers will need to re-evaluate their penchant for financing toll roads and new suburbs on the urban fringe. Many recent toll roads in Australia have gone bankrupt because the numbers of cars have just not materialised in the way the models predicted (Goldberg, 2009).

Urban economists will need to find a new way of measuring economic progress other than by the number of new cars sold.


The phenomenon of peak car use appears to have set in to the cities of the developed world. It seems to be due to a combination of: technological limits set by the inability of cars to continue causing urban sprawl within travel time budgets; the rapid growth in transit and re-urbanisation which combine to cause exponential declines in car use; the reduction of car use by older people in cities and amongst younger people due to the emerging culture of urbanism, and the growth in the price of fuel which underlies all of the above factors.

The implications for traffic engineers, planners, financiers and economists is a paradigm shift in their professional understanding of what makes a good city in the 21st century.  It does however point to the demise of automobile dependence.


Fels, M. F. and Munson, M. J. (1974) Energy thrift in urban transportation: Options for the future. Ford Foundation Energy Policy Project Report.

Goldberg, J.L. (2009) The Valuation of Toll Roads and the Implication for Future Solvency with Special Reference to the Transurban Group. Journal of Business Valuation and Economic Loss Analysis, 4 (1), Article 2.

Kenworthy, J. (2011) Update of Millennium Cities Database for Sustainable Transport, ongoing. (unpublished).

Kenworthy, J. and Laube, F. (2001) The Millennium Cities Database for Sustainable Transport, ISTP, Murdoch University, Perth and UITP, Brussels.

Kenworthy J., Laube F., Newman P., Barter P., Raad T., Poboon C. and Guia B. (1999) An International Sourcebook of Automobile Dependence in Cities, 1960-1990. University Press of Colorado, Boulder.

Leinberger, C. (2007) The Option of Urbanism: Investing in a New American Dream, Island Press, Washington DC.

Marchetti, C. (1994). Anthropological Invariants in Travel Behaviour. Technical Forecasting and Social Change 47(1): 75–78.

Millard-Ball, A. and Schipper, L. (2010) Are we reaching peak travel? Trends in passenger transport in eight industrialized countries. Transport Reviews, 2010, 1-22. First published on 18 November 2010 (iFirst).

Neff, J.W. (1996) Substitution rates between transit and automobile travel. Paper presented at the Association of American Geographers’ Annual Meeting, Charlotte, North Carolina, April.

Newman, P. (1995) The end of the urban freeway. World Transport Policy and Practice 1 (1): 12-19.

Newman P., Beatley T. and Boyer H. (2009) Resilient Cities: Responding to Peak Oil and Climate Change, Island Press, Washington DC.

Newman, P. and Kenworthy, J. (1989) Cities and Automobile Dependence: An International Sourcebook, Gower Publishing, Aldershot.

Newman, P. and Kenworthy, J (1999) Sustainability and Cities: Overcoming Automobile Dependence, Island Press, Washington DC.

Newman, P., Kenworthy J. and Glazebrook, G. (2008) How to Create Exponential Decline in Car Use in Australian Cities. AdaptNet Policy Forum 08-06-E-Ad, 08 July 2008. Also published in Australian Planner.

Newman, C.E. and Newman P.W.G. (2006) The Car and Culture. In Beilhartz, P., Hogan, T. (eds) Sociology: Place, Time and Division, Oxford University Press, Oxford.

Newton, P. (2010) Beyond Greenfields and Brownfields: The Challenge of Regenerating Australia’s Greyfield Suburbs, Built Environment 36 (1), (page numbers to come).

Puentes, R. and Tomer, A. (2009) The Road Less Travelled: An Analysis of Vehicle Miles Traveled Trends in the U.S. Metropolitan Infrastructure Initiatives Series, Brookings Institution, Washington DC.

Punter, J. (2003) The Vancouver Achievement: Urban Planning and Design, UBC Press, Vancouver, BC.

Romanos, M.C. (1978) Energy price effects on metropolitan spatial structure and form, Environment and Planning A, 10 (1): 93-104.

Schiller, P.L. Bruun, E.C. and Kenworthy, J.R. (2010) An Introduction to Sustainable Transportation: Policy, Planning and Implementation. Earthscan, London.

Stanley, J. and Barrett, S. (2010) Moving People – Solutions for a Growing Australia. Report for Australasian Railway Association, Bus Industry Confederation and UITP.

Watt, K.E.F. and Ayres, C. (1974) Urban land use patterns and transportation energy cost. Presented to the Annual Meeting of the American Association for the Advancement of Science, San Francisco.

*This article was first published  in World Transport, Policy & Practice Volume 17.2 June 2011.