Recently in Transportation Category

Below I posit some directions for research in transport and land use. Comments welcome.

1. We need more panels and time series and fewer cross-sectional analyses. If we want to establish causation, we need to look across time, otherwise, we are stuck simply with correlations. [And as we know, correlation is not causation]. We need data that examines the evolution and dynamics of transport and land use systems. I have not quite come to the conclusion that all analyses must be temporal (that is rejecting any atemporal analysis), but I am really tempted to do so as a reviewer.

2. We need to improve the scientific rigor of our research. The discipline is ripe for continuing meta-analysis to establish the magnitude of effects, and to reduce the range of estimates (and explain the range that exists through different underlying causal factors).

3. We need to more systematically consider network structure when looking at explanations of travel behavior. This includes measures of topology, morphology, and hierarchy. The measures that have historically been used have been relatively easy to estimate, but don't get at the gestalt of the network as an integrated system.

4. We need to systematically look at the difference between travelers perceptions of how systems operate and how long are travel times, and what we analysts measure. The differences can be systematically explained, at least in part, and people of course make decisions based on how they think the world works, not on how we think it does. We could then examine why perceptions differ from measurements, how much is simply differences in linguistic interpretation (when a trip begins and ends is somewhat ambiguous, e.g.), and how much is differences in time perception, and how much is "rounding" error, and how much is strategic to either impress with the length of the commute (which brings to mind the Four Yorkshiremen sketch) or to exaggerate in order to get sympathy or a policy response.

5. We need to increase the inter-disciplinarity in the study of transport and land use research, with planners, geographers, engineers, economists, and others working together looking at these problems.

6. We need more international and historical cases in the field to build towards a general truth. Reasoning is both inductive and deductive, but so much of what we are doing is complex, one often cannot simply derive from theory whether a change will lead to more or less travel, it depends on parameters, for instance. the fixed costs of engaging in a trip vs. the variable (and non-linear) costs of travel.

In defense of skyways

Sydney 62

Crossposted at and Photos of skyways by author from Sydney (1), Portland (2), Minneapolis (3), Tokyo (1), and Harrogate (1) respectively.

Everyone seems to be hating on Minneapolis's world-beating skyway network. Sam Newberg is the latest in a recent post at Is it Time to Remove Those Pesky Skyways? :

"The following post shares a similar argument as an article I wrote four years ago for the Downtown Journal (in Minneapolis). I was chastised at the time and suppose I will be again. However, with the recent opening of a new, $3 million skyway link to better connect the Accenture tower to adjacent blocks, as well as the new Downtown 2025 Plan taking on the “Skyway Paradox,” I was persuaded to bring it up again. So here goes: Isn’t it about time to start removing our skyways? A few years ago, Jen Gehl, a notable and well-respected Danish urbanist, was in town for an Urban Land Institute presentation. He noted downtown Minneapolis was “no longer up to the beat” of other world-class winter cities, blaming the skyways for striking a “defensive posture” against nature. Save for perhaps one bitter cold winter week per year, I couldn’t agree more. It doesn’t make sense to spend more than $1 million per skyway to perpetuate this anti-world class defensive posture. Gehl’s comments made it into the Skyway Conundrum section of the recently-released Downtown 2025 Plan, so someone is listening! While the plan doesn’t suggest removal, at least they admit the problem, and that, my friends, is the first step to recovery."

Portland Oregon 2001 12

I don't go downtown much for a variety of reasons, but pedestrian traffic-starved streets are not that reason. Following the model of Victor Gruen, downtown business interests made a decision in the early 1960s to build skyscrapers and skyways and reinforced that decisions continuously. While I am not convinced building skyscrapers was economically wise, given skyscrapers and an arterial street network on which every street and avenue is an entrance or exit to a radial freeway, skyways are a reasonable way to connect buildings. In economic jargon, while no cars downtown might be a "first-best" solution for pedestrians, we don't live in that world. Given the world where cars dominate streets, a pedestrian-only level is a viable "second-best" solution.

Downtown Minneapolis 2

Downtown Minneapolis 4

Downtown Minneapolis 5

  • Why should all of the modes interact on all levels. In principle, I like shared space as much as anyone, but I don't like walking on a sidewalk next to 3 or 4 or 5 lanes of motorized traffic, why should I be confined to a narrow building hugging strip rather than travel on a strictly pedestrian level.
  • Tall buildings should generate sufficient traffic to support retail on both the street level and the internal skyway level. In Planning for Place and Plexus we have a box "Ground Floor Retail Everywhere" which estimated that if all retail trips were home-based, 10 story apartment buildings would be sufficient to generate 1 floor of retail. A similar calculation could be done for non-home based (i.e. work-based) retail trips, and given the higher density of people per square foot in office buildings, should generate similar numbers. Short buildings don't justify skyways, but tall buildings do.
  • Skyways reduce inter-building transportation costs. This should increase inter-building activity and thus economies of agglomeration. Given the only purpose of cities is to connect people at low cost for some mutual advantage, the better cities connect people, the better off everyone is.
I have coauthored two papers about their evolution, I encourage you all to read the first: Corbett et al. (2009) Evolution of the second-story city: the Minneapolis Skyway System. Environment and Planning B: Planning and Design volume 36, pages 711 - 724, which goes into the history of the Minneapolis system. Could the skyways be better. Of course. Some ideas:
  • First, they can better connect to the street network with staircases or lifts adjacent to the sidewalks.
  • Second, they can follow a more regular topology. More importantly the internal skyway level network inside the buildings themselves could be far more navigable than it is. While it is fine for regular commuters who learn the ins and outs, its medieval labyrinth is horrible for the unfamiliar traveler.
  • Third, perhaps the skyway level should be on the 10th or 20th floor instead of the 2nd (The Petronas Towers at Kuala Lampur puts them at the 41st floor). This would require more coordination, but may be more useful in reducing the total amount of vertical movement required for inter-building personal transportation. It is probably a bit late to retrofit Minneapolis, but should be considered in cities newly adopting skyways.
Skyways are Minneapolis's Cable Cars, our London Underground or Route-Master Bus, our Venetian Canals. Skyways are the iconic transportation system of Minneapolis. With all else (roads, LRT, etc.) we are copy cats. We need to embrace skyways as such, and not listen to others who want Minneapolis to fit into the conventions of relatively weather-less European cities.

Harrogate 32

Tokyo 2006 186

Peak Drive-Thru

Cross-posted at and WFEmeraldUniversity Wells Fargo Bank has shuttered the drive-thru bank part of its branch at University and Emerald in Minneapolis (on the St. Paul City Line). [Google Street View image shown.] This may be for several reasons, the branch is immediately across the street from a Central Corridor LRT station (under construction), its road access has consequently been constricted. It would make a nice redevelopment opportunity, so this may simply be a real estate transaction. But perhaps there are other reasons. We have achieved peak travel in the US, and internet and electronic banking has replaced much drive-thru business. I, like many pedestrians and bicyclists, am annoyed with the hostility the drive-thru gives to non-auto modes. I was reprimanded for walking up to a drive-thru ATM at a Maryland National Bank in Columbia (after many acquisitions, now part of Bank of America) ... of course there was no walk-up ATM there, or I would have used that. If I don't want to or can't deal with a person, I still have to walk-up to the drive-thru ATM at my Credit Union on University Avenue, which still does not have a walk-up (and their machine looks circa 1980). The annoying part is not just the wrong height of the ATM and the poor User Interface, it is the cross-subsidy non-driving customers give to the driving customers, who pay no extra for the larger building and infrastructure they require. Drive-thru businesses have a long history in the US, dating at least from 1930 in the banking sector. Obviously gas stations were drive-thru, and I suppose it expanded from there. I had a fascination with these types of businesses as a child, both because of their (at least banks) use of pneumatic tubes, and just because of the futuristic feeling one had doing business from a car. I was impressed when I visited my aunt who went to a drive-thru dairy store in the Philadelphia suburbs. In the planned community of Columbia, Maryland, we did not have these, though drive-thru banks were allowed in the Village Centers, at first drive-thru restaurants were not, and certainly not drive-thru groceries. We eventually got a Fotomat knock-off, and I was fascinated by the miniaturization of retail. Visiting some southern town (I'm guessing Tallahassee, but it was a couple of decades ago) when I was in college, there was the drive-thru liquor and gun store (like this one, but different), everything for good-ole-boys to have a really good time on a Friday night. There is also a drive-thru romance store in Alabama, which seems less awful and gives a different meaning to the term 'quickie'. Of course there are drive-thru 'quick-serve' restaurants, and even Starbucks, which was once aiming to be a third space, in addition to these other oddball collections. Tom Vanderbilt in a Slate article on the subject notes McDonald's gets 65 percent of US sales from drive-thru. An hour of Googling does not give me a solid number of drive-thrus in the US, but Rheitt Allain estimates about 100,000. There is better data on all restaurants, apparently the number of restaurants in the US is dropping about 2 percent according to Nation's Restaurant News to 574,050 in 2011. One assumes drive-thrus are dropping as well, though independents are experiencing most of the fall. Overall, spending for food away from home has been dropping the past few years as a function of the recession and high gas prices. The total number of bank branches seems to have peaked in 2009 (i.e. it was down in 2010, whether this is short term or permanent is of course unclear), while the number of institutions is way off the peak due to consolidation and merger. All of this portends that the US may have saturated the drive-thru market, and the direction is moving down. It is still speculative, and future data will be required to confirm this, but if so, we may be facing a more walk-up America.

A Dictionary Of Transport Analysis

I have a couple of chapters (mine are under a Creative Commons license!) in the Recently published: Button, Kenneth, Henry Vega, Peter Nijkamp (2011) A Dictionary Of Transport Analysis Edward Elgar Publishing:

"This concise and clearly focused Dictionary, with contributions by the leading authorities in their fields, brings order and clarity to a topic that can suffer from confusion over terminology and concepts.

It provides a bridge between the academic disciplines involved and illustrates the application of transportation policy that crosses a variety of administrative divisions. Cutting through jargon, the entries concentrate on the social science aspects of transportation analysis, defining many of the terms used in transportation, and providing valuable information on some of the major institutions and technologies affecting this sector

This concise and comprehensive Dictionary will be an invaluable addition to libraries and research institutes and a helpful resource for anyone with an interest in the analysis of transport."

The inaugural World Symposium on Transport and Land Use Research
(WSTLUR) was held in Whistler, BC on July 27-30, featuring over 40
peer reviewed papers (submitted to the Journal of Land Use and
Transport, and keynote addresses from Ed Glaeser (Harvard),
Robert Cervero (UC Berkeley) and David Bannister (Oxford). Please see for the program and links to presentations and even
audio recordings of the keynotes.

The steering committee is now forming the World Society for Transport
and Land Use Research (WSTLUR), who will be charged with organizing a
subsequent symposium in 2014 and other aims of the Society. The
mission statement—broadly, to cultivate an interdisciplinary research
community/agenda--- is below.

Members of the society will elect the board (11 seats are open); the
board will then select its officers. (Please see bylaws posted at ; Kevin J. Krizek, University of Colorado, has been
appointed chair of the elections committee). If you are interested in
participating in this exciting international endeavor, we encourage
you to become a member of the society. Attendees of the World Symposium on Transport and Land Use Research
(WSTLUR) are already members.
Fees are $75 for three years
and can be registered by going to .

Elections for the board will commence Sept 15, 2011; if you are
interested in becoming a member and voting in the election, please
become a member by September 9, 2011.

If you or someone you know is interested in serving on the board,
please send a nomination to Kevin J. Krizek ( by
September 9. Anyone can nominate members for the board, however,
nominees must be (or become) a registered member of the society. A nomination
consists of:

-Name of the nominee
-Current position and affiliation
-A narrative (not to exceed 80 words and written in the third person),
describing the nominee’s activities, broadly speaking, in the area of
integrated transport-land use research.

Self nominations are allowed and all nominations need to be accepted
by the nominee. Please end only one email to Kevin J. Krizek
documenting the above process with the nominee’s full name in the
subject heading. (Self nominees would need to send only one email;
others would send one email with acceptance embedded).

Should you have any questions, please contact
Kevin J. Krizek (University of Colorado) at

The purpose of WSTLUR is to promote the understanding and analysis of
the interdisciplinary interactions of transport and land use and to
provide a forum for debate and a mechanism for the dissemination of
information. More specifically the aims include:
1. The exchange and dissemination of information at an international
level on all aspects of the theory, analysis, modeling, and evaluation
of transport-land use interactions and related policy.
2. The encouragement of high-quality research and application in the
above areas, through debates, publication, and promotion.
3. The provision of a clearinghouse for information on recent
developments in the field and to foster contacts among professionals
within and between various countries and different disciplines.
4. The promotion of international conferences, seminars, and workshops
on all aspects of transport-land use interaction.
5. The representation of the viewpoints of members to appropriate
national and international bodies, as required by the membership.
6. The preparation of regular communications to facilitate the above aims.

Via Good, Physorg reports on a recent paper: City dwellers produce as much CO2 as countryside people do: study:

"Most previous studies have indicated that people in cities have a smaller carbon footprint than people who live in the country. By using more complex methods of analysis than in the past, scientists at Aalto University in Finland have discovered that people's carbon emissions are practically the same in the city and in the rural areas. More than anything else, CO2 emissions that cause climate change are dependent upon how much goods and services people consume, not where they live."

Full article Jukka Heinonen and Seppo Junnila (2011) Implications of urban structure on carbon consumption in metropolitan areas Environ. Res. Lett. 6 (January-March 2011) 014018

If you buy Life-Cycle Analysis, this is one strike against sanctimonious urbanites in the GHG blame game.

Transportation at TED

There is a Minnesota Go Channel‬‏ on YouTube

, featuring more videos about issues facing the transportation community. Well worth visiting. As noted previously, my video is here.

Annie Lowrey in Slate Magazine: Long commutes cause obesity, neck pain, loneliness, divorce, stress, and insomnia. : "This week, researchers at Umea University in Sweden released a startling finding: Couples in which one partner commutes for longer than 45 minutes are 40 percent likelier to divorce."

(Via Marginal Revolution.)

Tyler Cowan, an economist at George Mason, writes about driverless cars ..

Regulations Hinder Development of Driverless Cars -

"IN the meantime, transportation is one area where progress has been slow for decades. We’re still flying 747s, a plane designed in the 1960s. Many rail and bus networks have contracted. And traffic congestion is worse than ever. As I argued in a previous column, this is probably part of a broader slowdown of technological advances.

But it’s clear that in the early part of the 20th century, the original advent of the motor car was not impeded by anything like the current mélange of regulations, laws and lawsuits. Potentially major innovations need a path forward, through the current thicket of restrictions. That debate on this issue is so quiet shows the urgency of doing something now."

(Via David King.)

See also: Marginal Revolution

We are pleased to announce the publication of Vol. 4, Issue 1 of the Journal of Transport and Land Use, available at

Table of Contents


Introduction: The Journal of Transport and Land Use enters year four

David M. Levinson



Agglomeration economies, accessibility and the spatial choice behavior of relocating firms

Michiel de Bok, Significance b.v., and Frank van Oort



‘New urbanism’ or metropolitan-level centralization? A comparison of the influences of metropolitan-level and neighborhood-level urban form characteristics on travel behavior.

Petter Naess


An application of the node-place model to explore the spatial development dynamics of station areas in Tokyo

Paul Chorus and Luca Bertolini


Defining land use intensity based on roadway level of service targets

Hamid Iravani, Arash Mirhoseini, and Maziar Rasoolzadeh


Impacts of ethanol plants on highway networks

Subhro Mitra, Alan Dybing and Denver Tolliver


Book Reviews

Review of "Gridlock: Why We're Stuck in Traffic and What to Do About It" by Randal O'Toole

Reviewed by David M. Levinson



The Journal of Transport and Land Use is an open-access, peer-reviewed online journal publishing original interdisciplinary papers on the interaction of transport and land use. Domains include: engineering, planning, modeling, behavior, economics, geography, regional science, sociology, architecture and design, network science, and complex systems.

It's Transportational



The verb "transport" means "to carry across", its noun form means the "act of transporting". The root "-ation" is one of those vague Latinisms, meaning an action or process, and so Transportation is therefore "the act of the act of carrying across", a needless redundancy, it says the same thing more than once. We do not "transportate", why do we have "transportation"?

According to Google, the word "Transportation" yields about 423,000,000 results while the word "Transport" yields About 698,000,000 results. Like the Metric System this is one area the US trails the world in efficiency. The Chinese require only two characters 交通 (Jiaotong) where the US requires 14 to convey the same idea. The figures on the right illustrate the usage worldwide, and in American and British English respectively. This excess "ation" is costing Google alone more than 2 Gigabytes, assuming only one excess "ation" per page.

Another way of thinking about is if this were printed, This would be a library of 4230 books just containing the word "ation", which would occupy a large room in The Library of Babel

Surely the word "transportation" is uttered more 423,000,000 times per year (which is only 1.5 times per year per American). If these words were spoken at 0.5 seconds per excess "ation", it would take one speaker (let's say Ray LaHood) 6.7 years of non-stop talking (24//7/365) just to utter this excess language, at 2000 hours per year, it would take nearly 30 work years for this individual, in other words, a career. At an average salary of $196,700 per year for Mr. LaHood, he is costing society almost in excess of $6,000,000.

We can provide more than three meals a day, according to some charities, for a dollar a day

For $6 million dollars we could feed 6 million children for a day, or more than 300 children for 18 years. Think of the starving children next time you utter that excess "ation".

The excess "ation" is only slowing us down, and is emblematic of the transportation problems we have in the US. Transport is Faster, twice as fast, with only two syllables doing the work of the four syllables in "transportation". By dropping those five letters, transport pronunciation speeds will double. Our work will be twice as fast on three-sixths as much paper. Meetings will be 17 minutes shorter. In these times of government cut-backs, it is essential the transport community contribute by sacrificing, this reduction of transportation to transport is a 35% letter savings, a much greater savings than can be achieved with an ordinary signal retiming.

Commentations are welcome.

World Symposium on Transport and Land Use Research

July 28-30, 2011
Whistler, British Columbia, Canada

We are pleased to announce the inaugural meeting of the World Symposium on Transport and Land Use Research (WSTLUR) to be held in Whistler, British Columbia, July 28-30, 2011. The conference will bring together academics and practitioners at the intersection of economics, planning, and engineering in the fields of transport and land use.

In addition to presentations based on rigorously peer-reviewed papers, the conference program will include confirmed plenary presentations from:

  • Ed Glaeser (Fred and Eleanor Glimp Professor of Economics, Department of Economics, Harvard University), Keynote Address
  • Robert Cervero (Professor of City & Regional Planning, University of California, Berkeley), Featured Luncheon Speaker
  • David Banister (Professor of Transport Studies, Oxford University), Featured Luncheon Speaker

The Call for Papers, seeking original and interdisciplinary research addressing the interaction of transport and land use, is open for submission until December 31, 2010.

With support from contributing partners, the conference is being organized by the Center for Transportation Studies at the University of Minnesota under the direction of the Organizing Committee and advisement from the Scientific Committee.

In August, 31 of last year I wrote:

As part of the NSF-funded STREET project, we have been putting together ''Fundamentals of Transportation'', a wikibook. I intend to use this next semester as the main text for my Introduction to Transportation Engineering course (CE 3201). We welcome comments and, since this is a wikibook, additions and edits. (Please login using your real name).

This book is aimed at undergraduate civil engineering students, though the material may provide a useful review for practitioners and graduate students in transportation. Typically, this would be for an Introduction to Transportation course, which might be taken by most students in their sophomore or junior year. Often this is the first engineering course students take, which requires a switch in thinking from simply solving given problems to formulating the problem mathematically before solving it, i.e. from straight-forward calculation often found in undergraduate Calculus to vaguer word problems more reflective of the real world.

Well, we are pleased to announce that Fundamentals of Transportation has now been recognized as a "Featured Book" on Wikibooks*. The book is by no means "complete"; but it is I think workable for its purpose, and again any constructive contributions (sections, chapters, new topics, new examples, new problems, better explanations) would still be welcome.

For those of you not familiar with Wikibooks, they operate using the same software and syntax as Wikipedia, and are editable by anyone, though only approved edits are visible. The nature of the project is the creation of textbooks and other references, rather than an encyclopedia, so each project retains its own point-of-view.

* other recent promotions include The Muggles Guide to Harry Potter and Small Numbers

Our long awaited research report Access to Destinations, Phase 3: Measuring Accessibility by Automobile
is now available.


This study describes the development and application of a set of accessibility measures for the Twin Cities region that measure accessibility by the automobile mode over the period from 1995 to 2005. In contrast to previous attempts to measure accessibility this study uses travel time estimates derived, to the extent possible, from actual observations of network performance by time of day. A set of cumulative opportunity measures are computed with transportation analysis zones (TAZs) as the unit of analysis for the years 1995, 2000 and 2005. Analysis of the changes in accessibility by location over the period of study reveals that, for the majority of locations in the region, accessibility increased between 1995 and 2005, though the increases were not uniform. A "flattening" or convergence of levels of accessibility across locations was observed over time, with faster-growing suburban locations gaining the most in terms of employment accessibility. An effort to decompose the causes of changes in accessibility into components related to transportation network structure and land use (opportunity location) reveal that both causes make a contribution to increasing accessibility, though the effects of changes to the transportation network tend to be more location-specific. Overall, the results of the study demonstrate the feasibility and relevance of using accessibility as a key performance measure to describe the regional transportation system.

Other reports in the series can also be downloaded here

London has just posted the Mayor's Transport Strategy . This is an exceedingly well done (and aesthetically pleasing) plan, even if you don't agree with every specific.

The next big things


I was interviewed by the Jim Foti of the Strib last month for their beginning of the decade article The next big things

My bit below:

COMMUTING New light-rail lines, many more MnPass lanes and cars that make driving decisions for you are in the commuting forecast for the next decade, says David Levinson, a civil engineering professor at the University of Minnesota.

Congestion levels won't change much, he said. The Twin Cities area will have more residents, but the aging population will be working less, and increased telecommuting will mean that people won't go into work as often.

The Southwest and Central Corridor rail lines are scheduled to start mid-decade, and one or two Minneapolis streetcar lines could be in the mix. Levinson expects highway expansion to mainly take the form of new MnPass lanes, which are for carpools, buses, motorcycles and toll-paying solo drivers.

He sees plug-in hybrids as the dominant car, meaning drivers will be buying less gas, so a per-mile fee will be implemented to replace lost tax revenue. Cars will keep getting safer, he said, with features such as automatic emergency braking and cruise control that adapts to the speed of surrounding traffic.


Recently published:

King, David, Kevin Krizek, and David Levinson (2008) Designing and Assessing a Teaching Laboratory for an Integrated Land Use and Transportation Course. Transportation Research Record: Journal of the Transportation Research Board #2046 pp 85-93 [doi]

The intersection of land use and transportation policy is becoming an increasingly important focus for all urban planners. This focus, however, challenges the academic community to design effective courses that teach the concepts and professional skills required for professional experience. Integrated land use and transportation courses should engage students to develop interdisciplinary skills while becoming familiar with, for example, travel behavior and zoning policies. Laboratory courses (or segments of courses) as part of graduate curricula provide platforms to further emphasize skills. A common pedagogy problem is devising laboratory assignments that are integrative, cumulative, practical, and interesting for students. Furthermore, laboratory projects should introduce students to real-world problems and techniques while exploring broad planning themes. This paper presents uses four years of laboratory segments from a land use-transportation course (LUTC) at the University of Minnesota to evaluate the needs and results of practitioner-oriented land use and transportation planning education. The laboratory used group projects where students proposed integrated developments using air rights above existing (and sunken) urban freeways in the Twin Cities. The projects provided a practitioner-oriented project through a collaborative and reflexive learning process. This article describes the completed projects, as well as the technical skills, integrated approach and visionary planning necessary for successful execution. The students addressed complicated problems associated with large-scale development by researching neighborhood demographics, characteristics, and pertinent regulations. They used their research to analyze traffic impacts, propose zoning regulations, and outline costs and benefits from their proposal using Geographic Information Systems (GIS), statistical analyses, assessor data and traffic engineering manuals. Using the completed student projects and comparisons with other land use-transportation course and laboratory projects the authors demonstrate how these laboratory components serve multiple pedagogy goals.

Keywords: Air Rights, Transportation-Land Use Planning, Education

Recently published:

Iacono, Michael, David Levinson and Ahmed El-Geneidy (2008) Models of Transportation and Land Use Change: A Guide to the Territory Journal of Planning Literature 22: 323-340.

Modern urban regions are highly complex entities. Despite the difficulty of modeling every relevant aspect of an urban region, researchers have produced a rich variety of models dealing with interrelated processes of urban change. The most popular types of models have been those dealing with the relationship between transportation network growth and changes in land use and the location of economic activity, embodied in the concept of accessibility. This article reviews some of the more common frameworks for modeling transportation and land use change, illustrating each with some examples of operational models that have been applied to real-world settings. It then identifies new directions for future research in urban modeling and notes the important contributions of the field to date.

Key Words: transportation planning • land use • mathematical models • urban growth • gravity model • microsimulation

The following was recently published:

Xie, Feng and David Levinson (2009) Modeling the Growth of Transportation Networks: A comprehensive review. Networks and Spatial Economics. 9(3) 291-307. [doi]

This paper reviews the progress that has been made over the last half-century in modeling and analyzing the growth of transportation networks. An overview of studies has been provided following five main streams: network growth in transport geography; traffic flow, transportation planning, and network growth; statistical analyses of network growth; economics of network growth; and network science. In recognition of the vast advances through decades in terms of exploring underlying growth mechanisms and developing effective network growth models, the authors also point out the challenges that are faced to model the complex process of transport development.

The following was recently published:

Corbett, Michael, Feng Xie, and David Levinson (2009) Evolution of the Second-Story City: The Minneapolis Skyway System. Environment
and Planning b
36(4) 711-724 [doi]

This paper describes and explains the growth of the Minneapolis Skyway network. Accessibility is used as a major factor in understanding that growth (i.e. does the network connect to the location(s) with the highest accessibility, followed by the second highest, and so on). First, employment opportunities are used as the measure of activity and are based off of the square footage of buildings and/or ITE trip generation rates. Using information about the buildings located downtown for each year since the first skyway was built, the accessibilities of each of the connected and adjacent unconnected blocks were calculated for every time period the skyway system expanded. The purpose is to determine how often the expansion connected the block with the highest accessibility. The results show that though important, accessibility was rarely maximized, except in the early stages of development. A connect-choice logit model relating the probability of joining the network (in a given year) to accessibility and network size was employed. The results show accessibility does remain an important factor in predicting which links are connected. Physical difficulties in making connections may have played a role, as well as the potential for adverse economic impacts.

Keywords: Network growth, Skyways, Minneapolis

I have argued that economics is a subset of transport economics, since transport economics includes time and space, and deals with the movement of many goods, while economics tends to be aspatial (and to a lesser extent atemporal) and focus on one good, money. The objective of this post is to suggest the equivalent of two fundamental relationships in two similar but largely unconnected fields, traffic engineering and macro-economics. These are the equation of exchange and the fundamental relationship of traffic.

The fundamental relationship of traffic says: Q=KV.
Q =flow (veh/hr) = Motorcars/Time (motorcars/time)
K= density (veh/km) = Motorcars/Distance
Vt = transportation velocity (km/hr) = Distance/Time

or in other words, dimensionally:
(M/D)(D/T) = M/T

The equation of exchange says: MVe=PY
where (quoting and rephrasing wikipedia):
M = the total amount of money in circulation on average in an economy during the period, say a year
Ve = economic velocity, or the velocity of money in final expenditures. (number of times a unit of money is spent in a given time period, e.g. a year). This differs from Vt.
P = the price level associated with transactions for the economy during the period
Y = total output per unit time.

We achieve equivalence if MV=PY can be mapped to KV = Q

First, let us assume that PY is the output, or GDP, this can be mapped directly to Q or motorcars per time

MVe=PY -> KVt = Q

where PY -> Q

So does MVe map to KVt ?

money supply * number of times money turns over per year =?= (number of motorcars / distance) * (distance / time)

So assuming money supply is a stock like the number of motorcars, and economic velocity Ve is in units of time-1, then it maps.

This equation is important in economics to understand inflation. If the money supply increases without any change in real output Y, than the price level must increase (if economic velocity Veis fixed), or the price level can remain constant if the velocity slows down (as in a recession when people spend less).

The equivalent in transportation suggests that if the number of cars in a system increases, and output flow remains constant, then a queue forms and velocity slows.

Other interpretations?


Wikipedia: Quantity theory of money
The New Palgrave Dictionary of Economics - money, classical theory of

Turning Traffic Upside Down

I we will be talking about Accessibility at the APA conference as well ( I have just discovered):
2009 APA National Planning Conference :: Turning Traffic Upside Down

Activity at a Glance Notes
Day Saturday
Time 1:00 PM - 4:00 PM

Ellen J. Greenberg, AICP
Richard W. Lee, AICP
David Levinson

See you in Minneapolis

Year In Ideas 2008

As KJK notes, the New York Times Year In Ideas 2008 has more than a handful of transportation ideas. Someone should do a retrospective and see how many of past year ideas turned out to be useful etc.

From WaPo: From Funding to Infrastructure, New Transportation Secretary Faces Major Problems

interviews the usual suspects, but probably useful to read.

From Times (of London) How bosses at Porsche outmanoeuvred Volkswagen

I never really understood why it is legal to sell things you don't own (with a promise to buy back later). Can't we have capitalism without fictitious goods?

International Transport Economics Conference
Incorporating the International Conference on Funding Transport

The International Transport Economics Conference (ITrEC) brings
together researchers, practitioners, and policymakers interested in
questions of transport economics. Topics include economic questions
relating to revenue and finance; congestion, pricing, and investment;
production function and cost estimation; transport demand; energy and
environment; safety; institutions and industrial organization; and
transport and land use. The conference is designed to appeal to
participants from varied backgrounds, including economists and
transport professionals in particular.

The conference has previously been held in Banff, Canada(2006);
Leuven, Belgium (2007); and Paris, France (2008).

Submission of Abstracts

Abstracts will be categorized and ranked by peer reviewers.
Theoretical, empirical, case-study, and policy-oriented contributions
are welcome. Abstracts of up to 1,000 words must be submitted
electronically by November 21, 2008 for

Key Dates

Abstracts Due: November 21, 2008
Abstracts Selected and Submitters Notified: January 2009
Final Papers Due (subject to acceptance): April 3, 2009
Early Registration Deadline: May 15, 2009
Conference: June 15-16, 2009
More Information

David Levinson
RP Braun/CTS Chair in Transportation
University of Minnesota

Sara Van Essendelft
Conference Coordinator
University of Minnesota

The conference is hosted by the Center for Transportation Studies at
the University of Minnesota.

A Theory of Modes

Wikipedia's article List of transport topics gives a list of a variety of modes largely defined by their technology (are they powered by animals or engines, are the engines on the vehicle or is the vehicle powered by a cable, do the vehicles travel on land, sea, or water, etc. While this is a reasonably comprehensive list and a reasonable organization of the subject for wikipedia, it does not really get at the transportation aspect of modes, focusing instead on their mechanical aspects.

I propose a schema that classifies passenger modes according to how they operate, not how they are paid for or what technology is employed:

The key attributes are:
* Availability (can you travel on demand, is a vehicle easily hailed, or is a reservation required?),
* Accompaniment (can your party travel alone, or is the ride shared with others?),
* Fixity of route ends (are the origin and destination of the route fixed?),
* Fixity of route stops (are the stops fixed, or does the vehicle stop anywhere between the origin and destination?),
* Fixity of schedule (does the vehicle adhere to a schedule?),
* Driver (does the party drive itself or rely on others?).

In this way, we can see the similarity or differences of seemingly different or similar modes.

Accompaniment Route Ends Driver Stops Schedule Example
Own Party Variable Self Variable Variable Car
  Variable Other Variable Variable Taxi
  Fixed Other Variable Variable PRT
Shared Variable Other Variable Variable Shared Taxi
  One end fixed Other Variable Variable Airport Express, Hotel Van
  Two ends fixed Other Variable Variable Jitney
    Other   Fixed Schedule Bus
    Other Fixed Stops Variable Elevator, People Mover
    Other   Fixed Schedule Rail, BRT
    Other Nonstop Variable Stagecoach
          Express Bus/Train
By reservation         Airline
Own Party Variable ends Self     Limosine
    Other     Car Share, Car Rental
Shared Variable ends       Paratransit

New method measures emotional quality of daily experience

"Some of the findings confirm what we already know while others are counter-intuitive. The researchers assessed how people felt during 28 types of activities and found that intimate relations were the most enjoyable, while commuting was the least enjoyable." Full article here (requires registration)

This observation contrasts with Redmond, Lothlorien S. and Patricia L. Mokhtarian (2001) The Positive Utility of the Commute: Modeling Ideal Commute Time and Relative Desired Commute Amount. Transportation 28 (2), 179 - 205 and fails to explain why if people hate commuting so much, they do so much of it. While I suspect few would suggest commuting to be the most enjoyable activity, it really depends on your commute.

Despite Kahneman's Nobel Prize, I think their methods were far more primitive than what is found in the transport and regional science literature (and if not for the NP, unlikely to have been published in Science), and they should have cited some of the prior transportation literature on this.

This issue arises of course because articles in emph>Science are noted widely, and cited broadly, this has emerged in a recent claim by Richard Florida about why cities are better than suburbs and "The Days of Urban Sprawl Are Over".

This is the third in a continuing series asking deep questions about the nature of transportation analysis. Previous episodes include:

1. Why do commute distances and times rise with income

2. The Transportationist: Are sunk costs sunk, is salvage value salvageable? A paradox in engineering economics analysis


3. Can small units of time be given the same value of time as larger units of time. In other words, do 60 improvements each saving a traveler 1 minute equal 1 improvement saving a traveler 60 minutes? Similarly, does 1 improvement saving a 1000 travelers 1 minute equal the value of time of a single traveler of 1000 minutes. These are different problems, one is intra-traveler and one is inter-traveler, but related.

Several issues arise.

A. Is value of time linear or non-linear? To this we must conclude the value of time is surely non-linear. I am much more agitated waiting 3 minutes at a red light than 2, and I begin to suspect the light is broken. Studies of ramp meters show a similar phenomena, as in our paper Weighting Waiting:
Evaluating Perception of In-Vehicle Travel Time Under Moving and Stopped Conditions

B. How do we apply this in a benefit-cost analysis? If we break one project into 60 smaller projects, each with a smaller value of travel time saved, and then we added the gains, we would get a different result than the what obtains with a single large project. For analytical convenience, we would like our analyses to be additive, not sub-additive, otherwise arbitrarily dividing the project changes the result. In particular many smaller projects will produce an undercount that is quite significant, and result in a much lower benefit than if the projects were bundled.

As a practical matter, every Benefit/Cost Analysis I have seen assumes a single value of time, rather than assuming non-linear value of time. (Alert me if you have a counter-example).

On the other hand, mode choice analyses do however weight different components of travel time differently, especially transit time (i.e. in-vehicle time is less onerous than waiting time). The implicit value of time for travelers does depend on the type of time (though generally not the amount of time). Using the log-sum of the mode choice model as a measure of benefit would implicitly account for this.

David Levinson

Network Reliability in Practice

Evolving Transportation Networks

Place and Plexus

The Transportation Experience

Access to Destinations

Assessing the Benefits and Costs of Intelligent Transportation Systems

Financing Transportation Networks

View David Levinson's profile on LinkedIn

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