Transport Poverty| A Political Economy of Access

We are pleased to make available Chapter 21: Transport Poverty of A Political Economy of Access. It opens:

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

When we talk about access as a value that should guide transport policy, we need to address access for whom, not just access to where by what mode. In the auto-dependent US, the mode that offers the most access in most places currently is the car. Yet cars are expensive, and many people struggle with basic access (and mobility) simply because they can’t afford it. Transport is the second largest spending category for US households, behind only housing. This is the case even as transport is heavily subsidized, regardless of mode.1 As discussed in Subsidy,2 the general approach is to spread whatever help is offered thinly across infrastructure capital investment. This does little to help those with the least.

How close is Sydney to the vision of creating three 30-minute cities?

This article, by Somwrita Sarkar, Hao Wu, and David Levinson first appeared in The Conversation.

The Greater Sydney Commission has proposed a 40-year vision of a metropolitan region formed of three “cities”: the Eastern “Harbour” City, the Central “River” City, and the Western “Parkland” City. The plan aims to create 30-minute cities, where the community has access to jobs and services in three largely self-contained but connected regions. Thus, Sydney would be polycentric.

The Greater Sydney Commission’s Three Cities Plan. Greater Sydney Commission

A polycentric city has multiple centres of employment, economic or social activity. Local labour markets and residential zones minimise long commutes, create a sense of place and neighbourhood, and strengthen economic agglomeration as companies, services and industries benefit from being close to one another.

However, it is still unclear whether Sydney is actually moving towards such a structure. In our recent work, we developed new ways of measuring polycentricity. We applied these to Journey to Work data from the 2016 Census to test how consistent the current centricity patterns of Greater Sydney are with the proposed plan.

How do you measure polycentricity?

Traditionally, employment densities are used as a measure of polycentricity. If the density of jobs in a location is higher than the average density for the entire region, then it is a centre.

However, this simple measure misses a key notion that makes cities what they are: network flows and spatial interactions. People “flow” from one place to another. Employment centres “attract” flows, and residential areas “produce” flows. Thus, a city is a collection of locations that interact dynamically, connected by daily commuting flows.

We proposed a set of new metrics to capture this idea of flows. We defined the net inflow of people to a location as the total number coming to this location to work minus the total number going from this location to work elsewhere. If the net inflows are positive, this place is a centre.

The chart below illustrates the idea. The base arc on the circle shows the number of people “flowing” out of a location to another location. The connecting arcs are coloured black if the net inflows into the focus regions (a), (b) or (c) are positive.

Testing polycentricity via net inflows: (a) Sydney City and Inner South (Sydney CBD), (b) Parramatta, (c) Eastern Suburbs. Source: The authors

Sydney CBD clearly emerges as a global centre for the whole region. Parramatta is a regional centre. Other locations such as the Eastern Suburbs are not centres at all.

The net inflow to a location can be divided by the total number of trips in the system, so inflow values are scaled from 0 to 1 using a standard statistical procedure. The higher the value, the higher the centre’s rank in the urban system. Here, a score of 1 means the centre is an absolute: all the trips in the system are a net inflow into the centre.

This gives us a trip-based centricity measure. And based on the area of the location, we can calculate a density-based centricity measure.

The maps below show trip-and-density-based measures – (a) and (b) respectively – for Greater Sydney at the Statistical Area Level 2 (representing a community that interacts together socially and economically).

Note the dominant role of the Sydney CBD. The other centres emerge as weak centres. Also, many of the second-order centres are very close to the CBD.

Visualising polycentricity in Sydney (red indicates highest values): (a) trip-based centricity, (b) density-based centricity, (c) transit-accessibility-based centricity, and (d) auto-accessibility-based centricity. Source: The Authors

The concept of accessibility

Counting the net inflow into a location may provide us with information about general centricity. However, it still does not tell us how easy or difficult it is for people to actually get to jobs. This brings us to the idea of accessibility.

Walter Hansen defined accessibility as “the spatial distribution of activities about a point, adjusted for the ability and the desire of people … to overcome spatial separation”. More practically speaking, a location is accessible if it can be reached within a set time (say 30 minutes) from another location.

We counted the net accessibility of a location by counting the number of jobs minus the number of workers (labour) that could be accessed from a particular location (SA2) in Sydney within 30 minutes. We counted travel time both by car and by public transport during a usual weekday peak hour (Wednesday 8am). Similar to the trip and density measures, accessibility centricities can also be scaled as values between 0 and 1. This allows us to compare across the four measures.

In the maps above, (c) and (d) show the transit and auto-based accessibility centricities based on accessibility for public transport and vehicles. Sydney CBD is highly accessible. The second-order centres show much weaker accessibility.

Takeaways for urban policy and the three-cities plan

The chart below shows the top-ranked centre, Sydney CBD (Level 1 centre), and the lower-ranked subcentres (Levels 2 and 3) emerging from our analysis.

Identified Level 1, 2, and 3 Centres for the Greater Sydney metropolitan region. Source: Authors

Accessibility planning should guide the design of a polycentric city

The design of polycentric Sydney should be guided by accessibility, the locations of jobs and homes, and subregional labour market organisation.

In short, the region should give priority to making jobs accessible by locating new jobs in emerging centres, instead of a mobility-focused system that takes people to jobs.

Reduce spatial mismatches between jobs and homes

Our results show that Sydney, paradoxically, remains strongly monocentric and strongly dispersed at the same time. The Sydney CBD accounts for 15% of jobs in the region, with the remaining 85% of jobs scattered around in weaker second-order centres and non-centres. Positive correlations exist between percentage of employed workers, trip-based centricity and the subcentre ranks.

But we see significant disparities between these ranks and accessibility centricities. This shows the spatial mismatches for commute lengths in the system.

A subcentre with high trip-centricity, employing a high percentage of workers, but relatively lower auto- and transit-based accessibility centricity, implies that even though a significant percentage of the population comes to this location to work, access to jobs at this centre within 30 minutes is low.

A policy response would be to increase the accessibility of jobs from this location, as it already serves as a centre. This situation is particularly clear in the cases of Parramatta-Rosehill and Macquarie Park-Marsfield. Penrith and Liverpool too have extremely weak accessibility centricity.

Parramatta CBD is emerging as a secondary centre in the Greater Sydney region, but with much weaker accessibility of jobs than Sydney CBD.haireena/Shutterstock


Polycentric cities should promote spatial justice

As cities grow in size, commute lengths increase if the labour market for the entire metropolitan region is integrated. Commute lengths will stabilise if a city has a clear polycentric or modular structure.

In the case of Sydney, spatial equity has always been a concern. However, inter-city comparisons show city size has a strong bearing on its equity and efficiency.

Our results show it’s increasingly important for larger cities to introduce a framework of subregional labour markets as part of the polycentricity agenda. Enabling shorter commutes for workers will improve spatial equity as well as efficiencies.


The article is based on this paper: Sarkar, Somwrita, Wu, Hao and Levinson, D. (2019) Measuring polycentricity via network flows, spatial interaction, and percolationUrban Studies. [doi])

How to increase transit ridership by up to 35% with one weird trick.*

This is a reprint from an article I wrote for The Conversation about our recent report “Catchment if you can: The effect of station entrance and exit locations on accessibility.”

Train riders have to get to stations somehow. This is often referred to as the “first mile” or “last mile” problem. There are many technical solutions to help travellers get from home to the station and back, ranging from cars to electronic scooters, but most people use a much older technology, their feet, to get from A to B. What is seldom considered is access to the train platform itself.

Stations are not points but places. They occupy a large area. A person walking at average speed takes about two minutes to walk from one end of a full-length eight-car train to the other.

Often platforms have a single access point on one side of the station, which makes it more difficult for people on the other side of the station to get to the platform. Passengers may need to almost circumnavigate the station to get to the platform. At an average walking speed, the extra distance they must backtrack adds up to six minutes per trip each way, our research has found.

Imagine being so unlucky to have an extra 12 minutes of travel time every day if you take the train. You might be tempted to drive instead.

Illustration of worst-case scenario, traveler lives west of the station with an East Platform and works East of a station with a West Platform, adding 6 minutes of travel each way, 12 minutes per day.

The table below shows the extra travel time in minutes depending on platform locations and access points for a traveller’s origin and destination. The average time for such a one-sided configuration of train stations is 3.25 minutes each way.
































Table 1: Additional Travel Time Depending on Origin and Destination Residence and Workplace Location vis-a-vis Platform Location.

While this example is hypothetical, it is drawn from experience in Sydney, where 44 of 178 train stations have only a single side entrance.

So what impact will a second entrance have?

We examined those stations and access to their platforms: how many people lived within 5, 10 and 15 minutes of the station platform, considering actual entrance location, and how many jobs were within 5, 10 and 15 minutes of the platform. Using existing ridership data from Opal cards, we estimated a model that related the passenger entry and exit flows at each station to that station’s accessibility.

Accessibility at train stations across Sydney. Author provided

We sketched a second entrance at those 44 stations and measured accessibility again. It’s now higher, as having two entrances instead of one means more people can reach the platform in the same time. We then estimated the increase in ridership from the model due to the improved accessibility, assuming no change in population or employment.

Over all 44 stations, total morning peak period entries increased by 5%. But some stations benefit a lot, and others not at all, so prioritisation of investments matters.

It will be no surprise to locals that Erskineville station comes out on top with a nearly 35% increase. While many of the new apartment-dwelling residents west of the station make the extra hike every day, even more would catch the train if there were a convenient entrance.

Other top 10 stations include: Bankstown, Newtown, Villawood, Redfern, Burwood, Sydneham, Caringbah, Meadowbank and Penshurst. Planning is already under way to improve Redfern station.

While this result considers existing development, adding a second entrance can make new transit-oriented development that much more valuable. This is because it will likely increase activity on the previously less accessible side of the station, as the example of Erskineville shows below.

Author provided


Other considerations include accessibility for people who cannot use staircases, as many of the stations are older and will require lifts. The prospects of park-and-ride lots, the costs of construction, the presence of nearby stations, and site feasibility also play into final decisions.

Our formal findings and details methods are summarized in this Executive Summary, and written up in this report: Catchment if you can: The effect of station entrance and exit locations on accessibility

The full Atlas is here: Atlas


A brief interview was ABC NSW News, Friday May 3, 2019, starting at 13:24 into the broadcast.

*Results vary by station.

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.