Dealing with the 5 Ps of access.

A nice review of Elements of Access in the Journal of Transport Geography …

  • Elisabetta Vitale Brovarone Dealing with the 5 Ps of access. Review of Elements of Access: Transport Planning for Engineers, Transport Engineering for PlannersJournal of Transport Geography 72 p. 274.
    Elements of Access: Transport Planning for Engineers, Transport Engineering for Planners. By David M. Levinson, Wes Marshall, Kay Axhausen.
    Elements of Access: Transport Planning for Engineers, Transport Engineering for Planners. By David M. Levinson, Wes Marshall, Kay Axhausen.
    • There is an indissoluble link between land use and transport. It might sound hair-rising to those who theorised the positive utility of travel, but basically, most of the time we spend travelling is to reach places where we can carry out activities. Since the pioneering studies of Robert Mitchell and Chester Rapkin in the ‘50s, several scholars have studied the link between land use and transport and tried to foster a constructive dialogue between these two domains. Nevertheless, they are still deeply separate, in terms of disciplines, professions and planning domains.

      The book is clearly aimed at bridging this gap, and more. It fosters an informed dialogue between transport engineers and spatial planners, grounded on mutual (more than reciprocal) knowledge. Furthermore, it tries to help both to communicate accessibility and its various facets to the public. …”

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?

On Hypo- and Hyper-connectivity in Transport

Connectivity is good. Is more connectivity better?

During the early stages of a useful technology like roads or transit, adding links generally adds more benefits than costs. However there are limits. A four way intersection is good does not mean a five way intersection (or six or seven) is necessarily better. The more complex intersection adds to the friction of travel and cost of construction over its simpler alternatives.

Muller's Hexagonal Network
Muller’s Hexagonal Network

A grid network, with streets at 90-degree angles to each other might not be as good as a network with streets at 60-degree angles, which reduces travel costs and increases directness (reduces circuity), but it is most assuredly better than a fine mesh with streets at 10-degrees or 1-degree, where almost all is pavement and little is actually buildable land. While 1-degree network would reduce surface travel distance, it does so at many other costs, including a reduction in accessibility because of fewer development opportunities.

Consider the circuity additions based on network angle. If all places are connected via a 90-degree square grid, the circuity at worst is SQRT(2), but on average 1.21.  So travel distance increases by 21% over a straight-line path. With a 60-degree grid, the circuity is lower, at worst 1.22, on average nearer 1.11. (Bus transit networks, which tend not to follow the shortest path, have much worse circuity.)

The optimal level of connectivity depends on what you are trying to optimize.

Hypo and Hyper are antonyms. Wiktionary says:

I would maintain that most developed countries are pretty close to optimal in terms of road connectivity, that there are few missing links whose costs outweigh their benefits. If subsidies for modes were to be eliminated, some large cities might be under-developed in terms of transit connectivity because of a bias towards coverage (and circuity) aims rather than frequency.

Let’s think of this in the context of induced demand. More connectivity in one sense means a faster network, which users exploit by traveling longer distances in the same amount of time. They gain utility by being in a house they prefer. However they use up the capacity gains of the network. But more connectivity increases the friction of connections (junctions, interchanges, transfers) which slows down the network. Induced demand due to connectivity is thus self-limiting.

Braess Paradox is the most famous supply side example of hyper-connectivity. In this situation, removing a link improves travel for road users at large because the additional network link induces travelers to use a link with a lower average cost but higher social marginal cost.

A key point is that whether a network is over or under-connected depends on the technology of travel, as well as the amount. A network which is overconnected for cars may be underconnected for pedestrians who don’t congest so easily. A network which is overconnected for 2000 cars may be underconnected for 1000. This is the challenge in building cities. Networks last for seemingly forever, but technologies that use them change more frequently. How can you design a permanent infrastructure flexible enough to serve future technology?


Access Quartet

I am pleased to have now completed my Access Quartet of books. These are artisanally selected from the last decade or so of my popular writings, including for the Transportist blog and elsewhere, along with new words to enhance their completeness.

They are organized so that they can be read independently, though an astute reader will identify several themes that run through them all, most obviously the need to privilege considerations of access when considering behavior, deploying technologies, designing infrastructure and networks, and deciding what to fund.

The books are beautifully laid out in the Tufte-latex template for clear information presentation and ease of reading. All are available in hardcover, paper, and PDF.

I thank my coauthors on the books, Kevin Krizek for The End of Traffic and the Future of Access, Kay Axhausen and Wes Marshall for Elements of Access, and David King for A Political Economy of Access for their contributions and extensive editing of my own writing. Each book also had numerous reviewers, who also made the books better.

You should read them all.


The End of Traffic and the Future of Access: A Roadmap to the New Transport Landscape. By David M. Levinson and Kevin J. Krizek.
The End of Traffic and the Future of Access: A Roadmap to the New Transport Landscape. By David M. Levinson and Kevin J. Krizek.
Spontaneous Access: Reflexions on Designing Cities and Transport by David Levinson
Spontaneous Access: Reflexions on Designing Cities and Transport by David Levinson
Elements of Access: Transport Planning for Engineers, Transport Engineering for Planners. By David M. Levinson, Wes Marshall, Kay Axhausen.
Elements of Access: Transport Planning for Engineers, Transport Engineering for Planners. By David M. Levinson, Wes Marshall, Kay Axhausen.
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

The U.S. has tried to build high-speed rail for 50 years | NPR Marketplace

Ben Bradford interviewed me and others (including Berkeley’s Betty Deakin) for the Marketplace story “Why can’t America build bullet trains?” I argue in a few seconds of airtime that intercity rail is not the best use of scarce public funds, which should instead be spent on urban travel. There is a related timeline at: “The U.S. has tried to build high-speed rail for 50 years


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.

It’s the (political) economy, stupid: when it comes to urban transport, we’re doing it wrong

Political choices, not technological innovations, shape our urban transport systems. As long as governments continue to prize mobility over accessibility, those systems will remain unhealthy and ineffectual.

[This is an edited extract from A Political Economy of Access by David M Levinson and David A King, available now in paper and PDF. It was published in Foreground.]

It is hard to examine the state of transport and land use planning without a large dose of cynicism about motives, and skepticism about claims and priorities.

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 engineering and land use planning are technical fields nominally grounded in rational thought. Yet level-headed analysis and calculations haven’t led to healthy and financially sustainable transport and land use systems. Part of what we see as the problem is a focus on mobility over accessibility. This focus prioritizes vehicular flows and speed over people and proximity. Our shared goals should not be how to maximize how much people and things travel about. Rather, our goals should be about how society can make it as easy as possible to reach opportunities and activities. A second part of the problem is privileging expansion over preservation. In a world where transport is new with few roads and no transit service, expansion is the critical phase of development; but in today’s world of mature networks, preservation is so much more important. We identify numerous problems, but the solutions are difficult to implement. That is not, we believe, because they are not good ideas, but rather because the institutions that make decisions are incapable of implementing them.

Our political economy analysis explains how access is shaped by law, culture, and governance. The issues we raise are not new, either. It was a century ago when Frederick Law Olmstead, Jr. said:

“There has been a decided tendency on the part of official street planning to insist with quite needless and undesirable rigidity upon fixed standards of width and arrangement in regard to purely local streets, leading inevitably in many cases to the formation of blocks and lots of a size and shape ill adapted to the local uses to which they need  to be put.”

This quote introduces many of our concerns. First, streets and road networks are more than just thoroughfares. They actively shape the location and function of the built environment, support or deter alternatives to automobility and substantially affect public safety. Second, in a system where transport networks and land regulations are designed and built separately, there are mismatched incentives. The most efficient road may contradict the needs of great places. Speed is not necessarily a characteristic of great cities – other than maybe Indianapolis, no city brags about being a raceway. Third, rigid roadway design is a hallmark of a focus on mobility.  The road itself is simply a conduit through which one passes, and the quality of destinations is diminished. Lastly, these are just some of the well-known problems that have persisted a century later, yet we have spent far less effort trying to understand why we keep building cities that many consider undesirable.

An additional issue is that transport systems require coordination across actors. The car you own is worthless without roads, and the capital and expertise required to build and maintain cars very much differs from the expertise needed for roads. The question remains how to integrate infrastructure, traffic flow, and land development. We advocate for coordination through prices, so people can account for the full cost of the actions of themselves and others when making decisions, whether as a traveler, developer, planner, or elected official.

The current state of transport and land use systems raises further concerns. New technologies are changing transport in fundamental ways. App-based services offer new taxi-type alternatives, which compete with and complement existing travel modes. These services are backed by deep-pocketed investors and despite their popularity are, as of this writing, not actually profitable. But there is little doubt that such services will persist in some form once the money runs out. If the history of taxicabs is any guide, a new era of regulation will protect Uber, Lyft, and others from their demise.

Private firms have reoriented transport planning priorities, for good and bad. Not long ago long-range transport plans largely set the course for policy and investment decades ahead.  Now everything from streetcars for real estate development to ridesharing through dockless bikesharingand, the flavor of  the week, electric scooters, are undermining the slow predictability of policy. With automated vehicles peeking over the horizon, the conventional approach to transport planning may be obsolete as no one knows what innovations and unintended side effects automation will bring.

The internal combustion engine is likely nearing the end of its century of dominance. These engines use fuel, which is taxed to pay for infrastructure across the US and in some other countries, and taxed for general revenue elsewhere. A shift to electricity affects the core relationship between user fees and public spending. New sources of revenue will have to be developed, including road tolls, road access charges, parking fees, and other sources. Of course, a loss of motor fuel taxes also will affect who pays for infrastructure. The role of central governments will likely diminish as fuel taxes decline. This devolution of authority pushes local and state or provincial governments to raise their own revenues. Voters will be asked to approve new taxes and fees, which introduces many concerns, including whether voters are adequately informed to assess the value of any package of taxes and spending.

Transport referenda are generally popular with the public in the United States, for example, where more than 70 percent usually pass. But voters often don’t know the true details of what they are voting on. California has led the way in voter-led projects, including their high-speed rail (HSR) project that voters passed with 52.6% of the votes in 2008. Despite well-publicized concerns, proponents promised a train that would connect the state, “[C]arrying up to 117 million passengers annually by 2030, with the capacity to also carry high-value, lightweight freight.” Since then, the timeline has been extended, the scope scaled back, forecast recanted, and the costs have increased dramatically – at one point to nearly $100 billion. Stations have been delayed or cancelled, and now the train is promoted as a commuter service to open up housing markets away from the extremely expensive coastal cities. The project is substantially different from what voters were sold, and a very passive aggressive solution to the state’s housing affordability crisis. We expect more projects like this.

Lastly, the political economy of access must address issues of race and social justice. New transit investments tend to favor wealthier, whiter communities. Bicycle advocacy is dominated by young, white men, as are the technology companies developing micromobility, services and microtransit and taxi apps. As once-young, white men ourselves, there is nothing wrong with that, but we have learned it is but one perspective of many.

The value we wish to promote is access. Access is the ability for people and firms to interact, whether through employment, production, consumption or sales. Access is a value that differs from mobility. Where mobility improvements are a hallmark of recent decades of transport policy, our focus on mobility has led to auto dominated infrastructure that offers few other options about how to get around. With a focus on access, we can orient transport policy to connecting people to places they want to be, rather than accommodating driving at the expense of everything else.

The political aspects of transport policy shouldn’t be assumed away or treated as a nuisance. Political choices are the core reasons our cities look and function the way they do. Many of the transport and land use problems we want to solve already have technical solutions. What these problems don’t have, and what we hope to contribute, are political solutions.

This is an edited extract from A Political Economy of Access by David M Levinson and David A King, available now in paper and PDF.

Professor David Levinson joined the School of Civil Engineering at the University of Sydney in 2017. He taught at the University of Minnesota from 1999 to 2016 where he held the Richard P Braun/CTS Chair in Transportation (2006-2016). He was Managing Director of the Accessibility Observatory, and directed the Networks, Economics, and Urban Systems research group.

David A King is an Assistant Professor of Urban Planning at Arizona State University School of Geographical Sciences and Urban Planning. His research explores the impact of local transportation planning on the built environment, public finance, social equity and accessibility.

Passenger rail between the Twin Cities and Duluth: How a monster was born and raised | StarTribune

Ailene Croup writes “ Passenger rail between the Twin Cities and Duluth: How a monster was born and raised” in the StarTribune, and mentions my name …

David Levinson spoke to community members at that time, informing them that passenger rail does not make enough money to pay for itself. It is subsidized by tax dollars.

Levinson held the Richard P. Braun/CTS Chair in Transportation Engineering at the University of Minnesota’s Center for Transportation Studies from 2006 to 2016. He served as faculty in the school’s Department of Civil, Environmental and Geo-Engineering and was noted as a prolific transportation researcher. He specialized in rail transportation.

He said the environmental impact of putting a train on the tracks was significant, such as the proposed multibillion-dollar rail line in California, which would leave a carbon footprint for 150 years.

The NLX project was finally turned over to MnDOT in 2016, but the alliance continues as a lobbying group supported by tax dollars from participating counties and cities. The alliance consists of and is now funded by the Hennepin County Rail Authority; the cities of Duluth, Minneapolis, Cambridge, Sandstone and Superior, Wis.; and the Mille Lacs Band of Ojibwe.

Through the years, private partnership with NLX was under discussion, but it never came to fruition.

The model for NLX has gone from high-speed rail to a less stressful ride from Duluth to Minneapolis where riders can tally “billable hours.” Or, a ride to college for students.

Levinson said it would take many hundreds of riders each day and many, many trips daily for NLX to even pay for itself.

The poor counties of central Minnesota do not need another transportation tax to take riders to Target Field. The rest of the state should not be responsible for subsidizing this luxury, either. Northstar Rail is the lesson, with taxpayers subsidizing $18 to $22 per rider since it was put on the tracks.

NLX has nothing to offer east-central and greater Minnesota other than the promise of higher taxes for subsidized transportation that does not serve them.

I have written about the NLX previously on the blog, and am surprised to see it alive, but I guess this confirms my thesis about zombies.