The automobile as prison. The city as freedom.

The automobile has been pitched as a machine for freedom. But you travel caged inside a small metal box, strapped to your chair, while your life is being threatened randomly by high speed two-ton projectiles, forced to keep eyes focused on the road and obliged to place hands at the 10 and 2 o’clock positions on the wheel, with your foot constrained to a small area on the floor. This doesn’t sound like freedom to me.

1925 Studebaker Patrol (Paddy) Wagon. Source: Wikipedia
1925 Studebaker Patrol (Paddy) Wagon. Source: Wikipedia

If you choose to enter a freeway, you are not even permitted to leave your car til you exit the road.

On streets, your behavior is governed by inanimate traffic lights, signs, and paint, which are violated at penalty of automatically generated fine or imprisonment.

This is all self-imposed, so it is more like committing yourself to an institution, the automobility asylum, perhaps, than prison which is imposed by others.

An alternative view is that freedom is not ensconced in a machine but in a way you can interact with the world. If you can, at your whim, when you want to, do what you want, engage in the activities you want, without fearing for your life, that is closer to freedom.

Jarrett Walker argues frequency is freedom. This is closer to the truth. While on a bus or train I am still caged in a metal box, it is a larger box, I am not strapped in, and I am much safer. I am also now free to do something with my time while in motion, not constrained to monitor the road.

And where can I travel in these safe freedom machines, reaching many more opportunities? Cities.  This gives a new meaning to the expression: Urban air makes you free.

‘But I can reach more places in a car than on transit in the same amount of time, almost everywhere,’ you argue. This is true, if you ignore the costs you impose on society, if you ignore the fixed costs of that opportunity to you, and if you ignore the ability to use time in some other way, as is available when not driving.

Freedom from car ownership, freedom from the obligation of driving, and freedom from negative externalities borne by the community at large are how we should reframe transport and land use goals. What can we do to give people those freedoms?

Measuring polycentricity via network flows, spatial interaction, and percolation

Recently published

Polycentricity, or the number of central urban places, is commonly measured by 10.1177_0042098019832517-fig1location-based metrics (e.g. employment density/total number of workers, above a threshold). While these metrics are good indicators of location ‘centricity’, results are sensitive to threshold choice. We consider the alternative idea that a centre’s status depends on its connectivity to other locations through trip inflows/outflows: this is inherently a network rather than placeidea. Three flow and network-based centricity metrics for measuring metropolitan area polycentricity using journey-to-work 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 Zipf-like or Christaller-like behaviours. Further, a percolation theory framework is proposed for the full origin–destination matrix, where trip flows are used as a thresholding parameter to count the number of sub-centres. Trip flows prove to be an effective measure to count and hierarchically organise metropolitan areas and sub-centres, tackling the arbitrariness of defining any threshold on employment statistics to count sub-centres. Applications on data from the Greater Sydney region show that the proposed framework helps to characterise polycentricity and sub-regional organisation more robustly, and provide unexpected insights into the connections between land use, labour market organisation, transport and urban structure.

I only get some satisfaction: Introducing satisfaction into measures of accessibility

Recently published


Travel time decay curves by mode

Improving accessibility is a goal pursued by many metropolitan regions to address a variety of objectives. Accessibility, or the ease of reaching destinations, is traditionally measured using observed travel time and has of yet not accounted for user satisfaction with these travel times. As trip satisfaction is a major component of the underlying psychology of travel, we introduce satisfaction into accessibility measures and demonstrate its viability for future use. To do so, we generate a new satisfaction-based measure of accessibility where the impedance functions are determined from the travel time data of satisfying trips gathered from the 2017/2018 McGill Transport Survey. This satisfaction-based measure is used to calculate accessibility to jobs by four modes (public transport, car, walking, and cycling) in the Montreal metropolitan region, with the results then compared to a standard gravity-based measure of accessibility. This comparison reveals a discrepancy between both measures of accessibility, particularly for public transport users. By combining this discrepancy with mode share data, we identify areas that may be targets for future investigations to better understand the causes for discrepancy. The study demonstrates the importance of including satisfaction in accessibility measures and allows for a more nuanced interpretation of the ease of access by practitioners, researchers, planners, and policy-makers.

Recently Published: Accessibility and the journey to work through the lens of equity

Recently published

Access Equity and the Journey to Work, context map
Access Equity and the Journey to Work, context map

Inequality in transport provision is an area of growing concern among transport professionals, as it results in low-income individuals travelling at lower speeds while covering smaller distances. Accessibility, the ease of reaching destinations, may hold the key in correcting these inequalities through providing a means to evaluate land use and transport interventions. This article examines the relationship between accessibility and commute duration for low-income individuals compared to the higher-income, in three major Canadian metropolitan regions, Toronto, Montreal, and Vancouver using separate multilevel mixed effects statistical models for car and public transport commuters. Accessibility measures are generated for jobs and workers both at the origin (home) and the destination (place of work) to account for the impact of competing labor and firms. Our models show that the impacts of accessibility on commute duration are present and in many cases stronger for low-income individuals than for higher income groups. The results suggest that low-income individuals have more to gain (in terms of reduced commute time) from increased accessibility to low-income jobs at the origin and to workers at the destination. Similarly, they also have more to lose from increased accessibility to low-income workers at the origin and to low-income jobs at the destination, which are proxies for increased competition. Policies targeting improvements in accessibility to jobs, especially low-income ones, by car and public transport while managing the presence of competition can serve to bridge the inequality gap that exists in commuting behavior.

Access to Destinations Data

Many years ago, we completed a project called Access to Destinations. The data from the project has been sitting on my hard drive for many years. I am happy that some of it is now preserved for posterity and open science by the University of Minnesota Data Conservancy. See:


Unfortunately, due to small methodological changes, these data are not directly comparable with more recent outputs, and the 1995 – 2005 data are really not directly comparable with the 2010 data either. It nevertheless might be interesting for selected applications.

Map Monday: Isochrones and the Thirty-Minute City | WalkSydney

I wrote a thing for WalkSydney: Map Monday: Isochrones and the Thirty-Minute City

Travel Time Platform is a website that lets users draw Isochrones, areas which can be reached in a given amount of time (Iso from the Greek for same, chronos for time). I have used it to draw a time radius. Here we show a 30 minute walking time from the Seymour Centre (near the WalkSydney world headquarters, but you can choose anywhere.)

The 30 minute city is a concept about accessibility, can the important places travelers want to go be reached in a given time. The idea that 70% of the people can reach daily activities within 30 minutes of walk, bike, or transit is embedded in the most recent Metropolis of Three Cities plan of the Greater Sydney Commission.

Isochrone by car. A car will get you farther than walking, biking, or transit in 30 minutes.
Isochrone by car. A car will get you farther than walking, biking, or transit in 30 minutes.


How more development can lead to less travel: Examples

Balancing housing and jobs, so that they are located near each other, logically reduces travel compared to a situation where those same jobs are far apart. This has long been understood in the transport planning community (see e.g. Cervero 1989, or my 1998 paper), but is not well grasped among the general public.

However, moving a fixed number of things around is not how cities actually grow. Telling place A you taking away their employment is controversial. More generally new things are added.

Development in Mascot. Photo by author.
Development in Mascot. Photo by author.

It is commonly asserted that more development adds to congestion. And often this is true. But not always, it depends on the type of development. More housing in a housing-rich and job-poor area will result in more total travel. More employment in a job-rich, housing poor area will do similarly. More housing in a job-rich area, and more jobs in a housing-rich area can actually reduce travel.

For our baseline case, imagine a city with two precincts separated by 2 km.

Precinct A: 1000 Jobs, 0 Resident Workers

Precinct B: 0 Jobs, 1000 Resident Workers.

The one-way (morning commute) trip table looks like:

Jobs 1000 0
Workers A B
0 A 0 0
1000 B 1000 0

Total daily travel to work is 2000 person km per day. (Everyone commutes from B to A). Travel on Link BA is 1000 at 2 km per trip, or 2000 person km traveled. (This just analyzes one-way trips. Round trip commutes would double this.)

Case 1. 

There is a proposal to intensify development in Precincts A and B, so each is more locally balanced.

Precinct A: 1000 Jobs, 500 Resident Workers

Precinct B: 500 Jobs, 1000 Resident Workers.

The new one-way (morning commute) trip table looks like (rounded):

Jobs 1000 500
Workers A B
500 A 498 2
1000 B 503 497
  • assuming 0.5 km intrazonal travel distance, using a doubly-constrained gravity model with a d_{ij}(-2) impedance function.

The Daily Travel on links:

AB = 2 @ 2 km

BA = 503 @ 2 km

within A = 498 @ 0.5 km (walking)

within B = 497 @ 0.5 km

TOTAL = 1507 pkt.

This is considerably less than the baseline case as many more travelers can reach their destinations locally. While there is still some commuting, it is far less than before.

Case 2.

There is a proposal to build a locally-balanced Precinct C halfway between Precincts A and B.

Precinct C has 500 Jobs and 500 Workers

The new one-way (morning commute) trip table looks like:

Jobs 1000 0 500
Workers A B C
0 A 0 0 0
1000 B 666.666667 0 333.333333
500 C 333.333333 0 166.666667
  • assuming 0.5 km intrazonal travel distance, using a doubly-constrained gravity model with a d_{ij}(-2) impedance function.

The Daily Travel on links:

BC = BA + BC = 1000 @ 1 km

CA = BA + CA = 1000 @ 1 km

within C = 166 trips @ 0.5 km

TOTAL = 2083 pkt.

In this example, the total person kilometers traveled (pkt) on the links connecting inter-city precincts is essentially identical to the base case, despite adding 500 residents and 500 workers halfway between each. There are an additional 167 pkt daily on the intrazonal market (within C), which is likely walking.

The total one-way commute travel per person however drops, from 2 km/person per day to about 1.38 km/person per day. The average trip length is reduced. The experienced travel is thus about one-third lower.

Case 3

Building on Case 1, completely balancing A and B (so each has 1000 jobs and 1000 workers) reduces one-way commutes further (to 1176 pkt)

The new one-way (morning commute) trip table looks like (rounded):

Jobs 1000 1000
Workers A B
1000 A 941 59
1000 B 59 941
  • assuming 0.5 km intrazonal travel distance, using a doubly-constrained gravity model with a d_{ij}(-2) impedance function.

So, it should be clear from this example that adding development can actually reduce total travel, if it is the right kind of development in the right places.

A Political Economy of Access: Infrastructure, Networks, Cities, and Institutions by David M. Levinson and David A. King
A Political Economy of Access: Infrastructure, Networks, Cities, and Institutions by David M. Levinson and David A. King

Transport Accessibility Manual Working Group

I am pleased to announce that the Transportation Research Board Annual Meeting will host the first in-person meeting of the Transport Accessibility Manual Working Group.


Transport Accessibility Manual Working Group

Monday 6:00 PM- 7:30 PM
Marriott Marquis, Mint (M4)

David Levinson, University of Sydney, presiding

Sponsored by:

Standing Committee on Bus Transit Systems (AP050)

One of the key problems is what to value when investing in transport or regulating land development. Accessibility — the ease of reaching valued destinations — connects transport and land use, considering both how easy it is to move and where things are located. While many planners know how to measure this, many don’t, and all could benefit from standardizing application to best practice. To that end, a working group would develop such a standard, which would clarify topics like how to measure, how to compute, how to present, and what to consider in terms of accessibility.



If you are interested in participating, please email me.

Full cost accessibility

Recently published:

Traditional accessibility evaluation fails to fully capture the travel costs, especially the external costs, of travel. This study develops a full cost accessibility (FCA) framework by combining the internal and external cost components of travel time, safety, emissions, and money. The example illustrated compares FCA by automobile and bicycle on a toy network to demonstrate the potential and practicality of applying the FCA framework on real networks. This method provides an efficient evaluation tool for transport planning projects.

Full Cost Access
Full Cost Access