January 23, 2010

Dynamist Blog: H.G. Wells Pans Metropolis

From Virginia Postrel, H.G. Wells Pans Metropolis.

Wells got urban centrifugal and centripetal forces quite well.

December 16, 2009

U.S. System for Tracking Traffic Flow Is Faulted

A link from AD in the NYT: U.S. System for Tracking Traffic Flow Is Faulted. I am not familiar with the system, but obviously publicly paid for data should be free to the public. I suspect this is a problem of either bureaucratic incompetence or crony capitalism in the previous administration. The technology (at least the travel time parts) will soon be obviated by crowd-sourced travel time information from GPS equipped cell phones, assuming someone can get critical mass on the number of "probe" vehicles.


November 16, 2009

All aboard! Northstar glides into the sunrise

From MinnPost: All aboard! Northstar glides into the sunrise

Northstar opened today - the Twin Cities can check one more urban gadget off the list, we now have (technologically incompatible) commuter rail and light rail. Take that cities with only one rail mode.

The Block

Via DK: The Block: The Complete History of Eldridge Street Between Stanton and Rivington. Nice animation by Zach van Schouwen.

October 28, 2009

The Bay Bridge is coming undone

The Bay Bridge is coming undone See picture at link

Article: Bay Bridge closed after repair falls apart

September 28, 2009

I-35W MnPass (HOT lanes) to open this week

From MPR I-35W MnPass (HOT lanes) to open this week The entire article talks about MnPass without mentioning I-394 (the link includes animations).

The interesting bit from a transportation perspective is the variable priced shoulders, and how well that works.

August 27, 2009

London Bus iPhone and iPod Touch Application

I wish I had this when living in London: London Bus iPhone and iPod Touch Application London Transport with augmented reality.

Fighting Ourselves Over Funding for Intracity Versus Intercity Transportation

Interesting discussion of HSR in The Transport Politic discussing my interview posted yesterday.

But Mr. Levinson fails to address the fact that investment is needed in both intercity and intracity corridors. Claiming that we should not fund high-speed rail because urban transit is more important is equivalent to saying that federal subsidies to air travel and non-urban highways should simply end, because metropolitan areas need more investment and travel between cities is less important.

Perhaps such subsidies should end. I am not going to be a modalist and support subsidies for mode A because mode B gets them, or even suggest any mode should get subsidies (unless a good economic rationale justifies it). Transportation, especially intercity transportation, is an economic activity foremost that should justify itself on economic grounds. There are of course social aspects to this as well, but going down that path to justify multi-billion dollar systems is indeed a slippery slope.

An argument could be made about strengthening intercity linkages to refashion the current metropolitan system into a megalopolitan system, where people more regularly interact between cities. (Switzerland writ large). If the division of labor is limited by the extent of the market, and transportation can be used to expand the market, the division of labor can therefore increase (i.e. be more specialized), which should have some positive effects for the economy (akin to agglomeration economies). The magnitude of this is uncertain (and certainly location-specific), but I think presents the best case that can be made in favor of HSR in the US.

That said, remember that real HSR (not the short term improvements to get to 90 or 110 MPH, which may or may not be a good thing, but is certainly not HSR) is a long term deployment, so it needs to be compared with cars 10 or 20 or 30 years hence, and the air transportation system over the same period. Cars are getting better from both an environmental perspective and from the perspective of automation technologies. The DARPA Urban Challenge vehicles need to be bested to justify HSR. Cars driven by computers should be able to attain relatively high speeds (though certainly not HSR speeds). Further they may move less material per passenger than HSR (trains are heavy), and so may have net less environmental impact. This really waits to be seen.

The table that Mr. Freemark assembled (link above) is interesting and is a useful way to arrange a comparison (user time, negative externalities) being two of the major considerations. Operating costs and capital costs would be good to include as well. But the table is a bit harsh on aviation. Convenience is in how the system operates, and while the security theater we face now, especially in older large airports, is a disaster, it is not necessarily what we will face 20 years from now. Airports will be closer for many people (especially in multiple airport cities like SF, LA, DC, NY) than downtown train stations, though certainly not for all.

INRIX National Traffic Scorecard

According to the INRIX National Traffic Scorecard, Minneapolis is the 10th most congested Metro area (for 2008, up 3 from 13 in 2007) in the US. This surprises me, as it is more congested than Atlanta, Phoenix, and Miami, (among others) which all seem worse. These numbers, compiled through GPS logs, compare with the TTI Urban Mobility Indicators, which places Minneapolis at 19 (for 2007), using data from loop detectors.

More interesting is that congestion is down ~ 20%, significantly more than VMT (which is not surprising, since we normally operate at the edge of congestion, and a drop in traffic in congested periods has a significant effect on reducing queue lengths ... no queue, no congestion.

The Weakest Link: The decline of the surface transportation networks

Recently published:

Xie, Feng and David Levinson (2008) The Weakest Link: A model of the decline of surface transportation networks. Transportation Research part E 44(1) 100-113. [doi]

This study explores the economic mechanisms behind the decline of a surface transportation network, based on the assumption that the decline phase is a spontaneous process driven by decentralized decisions of individual travelers and privatized links. A simulation model is developed with a degeneration process by which the weakest link is removed iteratively from the network. Experiments reveal how the economic efficiency of a network evolves during the degeneration process and suggest an "optimal" degenerated network could be derived during the decline phase in terms of maximizing total social welfare.

Keywords: Decline; Transportation network; Simulation; Welfare; Accessibility

August 26, 2009

Designing and Assessing a Teaching Laboratory for an Integrated Land Use and Transportation Course.

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

August 25, 2009

Models of Transportation and Land Use Change: A Guide to the Territory

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

August 24, 2009

Jurisdictional Control and Network Growth

Recently published:

Xie, Feng and David Levinson (2009) Jurisdictional Control and Network Growth. Networks and Spatial Economics 9(3) 459-483. [doi]

Transport infrastructure evolves over time in a complex process as part of a dynamic and open system including travel demand, land use, as well as economic and political initiatives. As transport infrastructure changes, each traveler may adopt a new schedule, frequency, destination, mode, and/or route, and in the long term may change the location of their activities. These new behaviors create demand for a new round of modifications of infrastructure. In the long run, we observe the collective change in the capacity, service, connectivity, and connection patterns (topology) of networks. This paper examines how a fixed set of places incrementally gets connected as transport networks are constructed and upgraded over time. A simulator of network incremental connection (SONIC) is constructed to model the process of incremental connections and examines how networks evolve differently under centralized versus decentralized jurisdictional initiatives. Exploring the mechanism underlying this dynamic process can answer questions such as how urban networks have developed into various topologies, which network patterns are more efficient, and whether and how transport engineers, planners, and decision makers can guide the dynamics of land uses and infrastructure in a desired direction.

Keywords Network growth - Transport economics - Incremental connection - Jurisdictional control

August 23, 2009

Modeling the Growth of Transportation Networks: A comprehensive review

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.

August 22, 2009

Topological evolution of surface transportation networks

The following was recently published:

Xie, Feng and David Levinson (2009) The Topological Evolution of Road Networks.
Topological evolution of surface transportation networks
Computers, Environment, and Urban Systems 33(3) 211-223 [doi]

This study explores the topological evolution of surface transportation networks, using empirical evidence and a simulation model validated on that data. Evolution is an iterative process of interaction, investment, and disinvestment. The temporal change of topological attributes for the network is also evaluated using measures of connectivity, density, heterogeneity, concentration, and connection patterns. The simulation model is validated using historical data from the Indiana interurban network. Statistical analyses suggest that the simulation model performs well in predicting the sequence of link abandonment in the interurban network as well as the temporal change of topological attributes. The simulation model is then applied on different idealized network structures. Typical connection patterns such as rings, webs, hub-and-spokes, and cul-de-sacs emerge in the networks; the spontaneous organization of network hierarchies, the temporal change of spacing between parallel links, and the rise-and-fall of places in terms of their relative importance are also observed, providing evidence for the claim that network topology is an emergent property of network dynamics.

PACS numbers: 89.75.Fb, 89.75.-k, 89.75Kd

August 21, 2009

Input Taxes, Output Taxes and Electric Vehicles.

From ArsTechnica Ford's plug-in hybrids will talk to electrical grid This is for charging the cars at the best time of day (night), but in theory could be extended to a means for charging cars for electricity different than regular electricity, in other words, a mechanism for replacing the gas tax with a different energy input tax.

Fuel (or electricity) taxes are input taxes. Theory suggests it would be better to tax outputs (actual miles traveled, by time of day and location). This would send a more direct signal to consumers about the costs they impose on the system and others. The difficulty is that this may be a much more difficult enterprise from a variety of points-of-view (collection costs, political acceptability, and even technology (GPS shadows etc.). As a second-best, input taxes are not too bad, it is better than a tax totally unrelated to usage, and the 20-30% reduction in collection costs may well make up for any inefficiencies.

Evolution of the Second-Story City: The Minneapolis Skyway System.

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

August 10, 2009

Special Issue on the Evolution of Transportation Network Infrastructure in Networks and Spatial Economics: Volume 9, Issue 3 (2009)

A special issue of Networks and Spatial Economics on the Evolution of Transportation Network Infrastructure, for which I was the editor, is now out. Many thanks to my co-authors and the journal for making this happen. (I cannot however see the final version, as it is behind a pay-wall and my university does not yet subscribe to the journal. I have read all of the articles though, and it is well worth reading if you do have access).

Introduction to the Special Issue on the Evolution of Transportation Network Infrastructure
David Levinson

Modeling the Growth of Transportation Networks: A Comprehensive Review
Feng Xie and David Levinson

Inter-Modal Network Externalities and Transport Development: Evidence from Roads, Canals, and Ports During the English Industrial Revolution
Dan Bogart

The Efficiency of the Victorian British Railway Network: A Counterfactual Analysis
Mark Casson

Graph-Theoretical Analysis of the Swiss Road and Railway Networks Over Time
Alexander Erath, Michael Löchl and Kay W. Axhausen

Co-evolution of Density and Topology in a Simple Model of City Formation
Marc Barthélemy and Alessandro Flammini

The Topology of Transportation Networks: A Comparison Between Different Economies
Efrat Blumenfeld-Lieberthal

Jurisdictional Control and Network Growth
Feng Xie and David Levinson

July 30, 2009

International Symposium on Transportation Network Reliability

International Symposium on Transportation Network Reliability

Save the Date and Call for Papers

July 22-23, 2010 University of Minnesota, Minneapolis, Minnesota

The aim of the International Symposium on Transportation Network Reliability (INSTR) is to bring together researchers and professionals interested in transportation network reliability to discuss both recent research and future directions in this increasingly important field of research. The scope of the symposium includes all aspects of analysis and design to improve network reliability, including:
• user perception of unreliability
• public policy and reliability of travel times
• the valuation of reliability
• the economics of reliability
• network reliability modelling and estimation
• transport network robustness
• reliability of public transportation
• travel behaviour under uncertainty
• vehicle routing and scheduling under uncertainty
• risk evaluation and management for transportation networks
• ITS to improve network reliability

Submission of Papers
Papers will be categorized and ranked by peer reviewers. Theoretical, empirical, case-study, and policy-oriented contributions are welcome. Papers must be submitted electronically at byDecember 23, 2009 for consideration.

Key Dates
• Papers Due: December 23, 2009
• Papers selected and submitted: January 2010
• Final Papers Due (subject to acceptance): February 2010
• Early Registration Deadline: June 1, 2010
• Conference: July 22-23, 2010

More Information

Visit the INSTR Web site at

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.

July 10, 2009

Nearest Tube

This looks like the coolest iPhone app yet: Nearest Tube, an augmented reality application to find London Underground stations. by acrossair. I have not yet played with it.

Update: from Venture BeatAugmented reality subway app comes to NY, SF

July 9, 2009

New U of M report suggests transportation revenue alternatives

The St. Paul Legal Ledger has a nice article on Value CaptureNew U of M report suggests transportation revenue alternatives

July 7, 2009

Low Quality vs. High Quality Transit Services

Imagine there are two transit services in an area, a low quality system (L) that is pervasive (everyone is within 400 m of a low quality stop) and a high quality system (H) that is skeletal (only a small fraction are within 400 m of a high quality stop).

Imagine there are two classes of potential users, poor people (P) who will use either system, and rich people (R) who will use only the H routes.

Poor people perceive the system as larger (both L and H) and get more network externalities from the system. They can go anywhere in town on transit. Rich people see a small system, and perceive few network externalities. They can only go places on the H system.

As a consequence, poor people are more likely to use the system than rich people.

There are several solutions to this problem. The expensive solution is to build high quality services everywhere to attract the fraction of R that would not otherwise take transit. The less expensive solution is to change the perception (and reality) of the low quality system so it appears higher quality. Give it as many of the same features of H as possible, starting with information (e.g. what bus stops at the bus stop, when does it stop, what hours does it operate, where does it go, what does the local neighborhood look like, is the bus ontime, how much does it cost) and navigability.

Why do we never consider the less expensive solution?

July 5, 2009

Airport sign cost jumps past $2 million

From Strib: Airport sign cost jumps past $2 million. Probably should make clear that it is more than one sign, not clear from the article how many though.

Faced with complaints that an estimated 20,000 people show up at the wrong terminal each year, MAC has been considering proposals to change the terminal names on the signs and list the airlines that fly out of each terminal.

20,000 out of some 35,000,000 is about 1 out of 1750. If the 20,000 number is remotely correct, this does not seem to be much of a problem, as a commenter notes "you can't cure stupid". I suspect each of us goes to the wrong place more frequently than 1 out of every 1750 trips (or say once every two years). Another way of thinking about it is 1 passenger on every 10 flights showed up at the wrong terminal (and even that is rectifiable by taking the LRT between terminals if they got there early enough).

Of course signs are expensive, and it is important to convey information to travelers, but is there really a problem if only 20K out of 35M get lost?

July 1, 2009

Urban planning as consensual illusion.

William Gibson's Neuromancer defines cyberspace as a "consensual illusion" obtained when a user "jacks into" the network. Plans for cities are also consensual illusions, a community agreed upon vision of how the city will look at some future date. Planners are but illusionists, creating and shaping a fantasy for a how city imagines itself, and through this consensus, harnessing the positive feedback processes of public and private investments aiming to achieve self-fulfilling prophesies. By promising networks, development will come; by promising demand, infrastructure will come.

Reflections on the Streetcar of Portland

Riding for a conference from the Portland airport to Portland State University on Light Rail Transit (LRT) and then streetcar gave me time to reflect on the Elysian Fields of transportation engineering, the Nirvana of networks and nexi.

Portland, Oregon is one of the major battlegrounds in the mode wars (car vs. transit and the internecine rail vs. bus). It has since the 1980s been held up by planners as the exemplar American city that does almost everything right. The foremost thing they do right in the view of the planning establishment is promoting LRT and bicycling.

The fascination with rail transit in particular (especially as compared with bus) was something I have never quite grokked. As a rational observer with formal training in transportation, I have had a hard time understanding the emotional relationship people have with rail. Why do people like LRT more than bus? Is it simply how we operate them, or that it is modern capital, or is there a psychological benefit associated with deterministic tracks vs. widely diverging roads? There are lots of theories on the matter, I will identify a few below.

1. Ride quality. The quality of the ride on an LRT is smoother and less herky-jerky than a bus, and passengers have a nicer facility.

2. Navigability. It is hard to navigate current US bus systems, while the fewer number of rail lines are fairly easy to figure out. Because trains cannot steer, they cannot get lost the way a bus can.

3. Speed. Trains are faster than local buses, especially if they have their own right of way and few stations.

4. Permanence. I can make a permanent investment decision based on the location of rail lines, as the transit system is committed to this line, while a bus line may be temporary.

5. Nostalgia. People who like LRT recall (or wish they could recall) the immediately post-World War II America when streetcars were at a maximum. 1946 was a magical period in US history, a boom following the long depression, when streetcar networks if not at a maximum were really close. (Coupled with a conspiracy theory about their removal)

6. Sexuality. This is part of the theory presented by Jonathan Richmond's in his book Transport of Delight and earlier paper The Mythical Conception of Rail Transit in Los Angeles. The image of the train entering the tunnel clearly evokes a primal response.

There are logical rejoinders for the first four (though not the nostalgia or sexuality argument I suppose), the most obvious is that if you spent the kind of money you are spending on rail on buses instead, and operated them better, buses would be quite nice. Navigability could be improved with a bit of thought (and trains can divert), while permanence of the last generation of streetcars (1887-1954) clearly was temporary.

The theory I have now adopted comes from my recent trip from Minneapolis to Portland accessing the airport at both ends via LRT, and then riding the Portland streetcar almost full circle. Rail transit forms an urban superstructure. Guideway transit, esp. LRT makes the city more like a single structure, and makes everything seem closer. The LRT vehicle is continuously running, and if activities are along the path of the vehicle, everything seems quite coordinated. In a way by organizing activities linearly (or multi-linearly), it simplifies the city. Hopping on a train is much like getting on an elevator.

LRT, like walking indoors, keeps you enveloped within civilization, while walking, biking, or driving is a frontier experience, you alone in the wilderness. (And bus falls in-between). We can posit that distances within buildings seem shorter than distances between buildings (Some literature along the notions of this idea exist, see Tversky, but it is not directly on point). Distances connected by the urban superstructure will likely feel closer than those which are not so connected. Walking through a modern airport, or the Minneapolis Skyway, will tell you enveloped distances can be quite large, but still not feel as large as leaving one building into nature for another.

Preferences for civilization or frontier-crossing (or degree of each) vary across individuals. Driving of course places you in a machine, but you, not civilization, are operating the machine, so just as driving is freedom, not everyone wants that freedom to drive, they may prefer freedom from driving. The extent to which you believe in the importance of community over individuals (or vice versa) will affect your perception of the issue.

( LRT may also be more popular than traditional underground subway (Metro) systems. People of course like being able to walk out the door and step onto a train more than having to descend through the gates of hell, Metro to get to the underground subterranean system. There are many reasons, not least of which is the extra time and energy required to so descend. The advantages in principle are faster point to point travel time, but that depends on the access cost vs. the in-motion speed. )

Transit invokes further passions because of the positive feedback loop between ridership, revenue, and route frequency, especially where transit is weak as in much of the US. My riding transit creates a positive externality for you (more riders, shorter headways, and more routes), so of course if you ride transit, you want to impose your preference on me. It is only selfishly rational. Further cars use scarce roadspace. While similar feedback loops may exist on the highway side (more drivers means more closely spaced roads), congestion mitigates that and the network is largely built out, so drivers do not feel the same need to impose their modal preference on the transit riding minority. Finally, drivers may benefit in the short term if other drivers take transit. (Where transit is already congested and frequent, additional riders produce few positive externalities as diminishing returns set in).

Value Capture for Transportation Finance

Our Value Capture for Transportation Finance study is now out.

Detailed reports will be placed online soon.

About the Study

Large public investments in state transportation infrastructure--such as new freeway interchanges, highways, or transit stations--can increase the value of adjacent private land, sometimes substantially. Capturing the value of this benefit through various tools is gaining interest as a finance mechanism for infrastructure investments. But many questions remain: Does "value capture" promote or hinder economic development? How high should the tax rate be? How stable is the revenue?

To answer these and other questions, the state legislature appropriated funding to CTS to study the public policy implications of value capture.

Researchers reviewed the relationship between transportation and land values, including the measurement of benefits from a transportation improvement, as well as the legal and economic frameworks for capturing the value gains. They explored the major financing techniques associated with value capture--such as joint development of infrastructure and adjacent private parcels, rezoning and reselling, impact fees, special assessment districts, and tax increment financing--and some examples of their implementation. They then evaluated several of the proposed policies and their suitability for implementation locally, based on the criteria of economic efficiency, social equity, adequacy as a revenue source, and feasibility.

June 27, 2009

"Killed by Garbage Truck"

I noticed two people have been killed by garbage trucks in Minnesota in the past few weeks, and did a google search for the phrase "killed by garbage truck", it is not as uncommon as it may seem, or as it should be. A sampling from the first few pages of the Google search below:

I could not find a systematic database of these (which is not to say no one is tracking this, I just don't know). So the question is, are these random tragedies, or is there a systematic problem (lack of safety equipment on trucks, poor driver training, poor pedestrian/bicyclist training)?

June 11, 2009

Data Center Overload

In NY Times, a nice article by Tom Vanderbilt (of Traffic fame) Data Center Overload - about the rise of Data Centers on internet based networks (virtual downtowns for the information age?)

Best quote "We have an almost inimical incuriosity when it comes to infrastructure."

June 2, 2009

Planning Propaganda

Via ACSP newsletter, a great UK propaganda film from 1948: Charley in New Town

Houses and Highways

From BBC Radio 4: Audio slideshow: Houses and highways some nice pictures and standard explanations of post-War US.

May 28, 2009

How constraints drive growth

A city is a positive feedback loop in space.

Why locate anywhere but to be near something or far from something? Cities offer opportunities to be near lots of things (people), and as cities exist, those things must be of value to the people who locate there. By locating, people add to the "stuff" others can reach.

Accessibility is a measure of nearness to things (people), e.g. how much stuff you can reach in x minutes time. Which stuff matters and how much time is acceptable depend on individual preferences, but these can be measured and observed. An area with higher density enables you to reach more stuff in less time because it is physically closer, even if the network is slower (you can move less distance per unit time), provided the density increases at a rate faster than slowness increases.

Some cities are physically constrained, notably San Francisco (a peninsula) and Manhattan and most of New York (islands). In fact, the five densest cities in the US (New York, San Francisco, Los Angeles, Honolulu, and Chicago) all have some significant physical constraints (island, peninsula/bay, mountains/ocean, island/mountains, lake) hemming them in. Not surprisingly, these are among the most expensive cities in which to live. This indicates that the location is especially valuable, because of the accessibility benefits it provides.

Perhaps it is the constraint itself which creates value. Because of the constraint, more people and firms are bidding for scarce space (since the non-scarce non-central available space has a much higher transportation cost (across the bay, off the island, in more distant suburbs) driving up rents. As a consequence, developers build at higher density in the core city, increasing accessibility. Because of the higher density, there is higher accessibility, creating value for residents and businesses, leading to even higher rents. Location has positive spillovers.

A city is a positive feedback loop in space. Spatial constraints accelerate the loop.

May 19, 2009

Presentation at CTS Research Conference

My presentation on the Access to Destinations project on the morning of May 19, 2009 at the Center for Transportation Studies Research Conference in Bloomington is now posted: Destinations Count: Counting Destinations (warning 62 MB)

April 22, 2009

Demolition Means Progress

From the NY Times: An Effort to Save Flint, Mich., by Shrinking It

I worked in growth management back in the day, but now Berkeley has a program called "Shrinking Cities in a Global Perspective Program".

Overall, it seems a shame to let all that sunk capital and infrastructure go to waste, and the wasted human capital associated with high unemployment also seems like it should be a temporary disequilibrium, surely someone could make use of it.

March 23, 2009

more maps

Some map links:

Unbuilt Robert Moses Highway Maps on Google maps


subways at scale

February 8, 2009

Hacking an Electronic Road Sign

On Bruce Schneier Hacking an Electronic Road Sign. Now maybe someone can change the "Suspicious Activity Call 911" signs near the MSP Airport and this parody of a police state.

November 22, 2008

The End of Daylight Savings Time

From Green Daily Obama Should Axe Daylight Time

If it doesn't save energy, and may cost lives according to "The effects of daylight saving time on vehicle crashes in Minnesota" ( a recent working paper by Arthur Huang and myself), we should end this charade once and for all.

If you want more useful daylight at the end of the work day, don't change the clock, just go to work earlier!

November 12, 2008

World Usability Day

I will be speaking at Design and Go, an event at the St. Paul Union Depot Nov. 13 6-9 pm on Accessibility as part of World Usability Day.

October 26, 2008

Have the suburbs won

Joel Kotkin in the wapo: Rule, Suburbia

and in New Geography: Turns Out There's Good News on Main St.

The latter critiqued nicely in American Scene: You Can't Say It's Half Full When it's Three Quarters Empty

October 22, 2008

Roads, Rails and Urban Change

I am a bit tardy on this, but people tell me I look fabulous.

Twin Cities Public Television will air on its Minnesota Channel:

Roads, Rails and Urban Change

Journey through the history of transportation and examine the key transportation topics facing Minnesota planners and policy makers in the near future. Co-produced with the University of Minnesota Metro Consortium.

According to the program guide it will appear:

Sunday 10/19 6 pm,

Sunday 11/9 at 9 pm

Comcast St. Paul Channel 243

Comcast Minneapolis Channel 202

Mediacom Channel 102

Over the Air Digital, Channel 17-2.

I am sure it will be repeated long through history, and eventually will find its way to the Internet, but in the interim, set your Tivos if you are a Minnesota local.

August 23, 2008

Cloud Commuting

Once upon a time, people kept their life savings on their person or at their homes, stored in physical material like gold and jewelry and property. Then money was invented as a medium of exchange, and people stored a surrogate of their wealth. Then banking was invented, and people centralized their holdings in a bank, and were paid interest for the privilege. Why were they paid? Because the banks could reuse their money by lending it out, at an even greater rate of interest. Money is fungible. I do not lose anything by storing it at the bank (and allowing them to lend it) except the privacy of keeping secret how much money I have, and risk that the bank will be unable to pay me back. The first is resolved through regulations, and the use of multiple banks, the latter by insurance. In any case, it is much safer than storing the money in a mattress at home.

Once upon a time, people kept their life's information on their person or on computers at their home or work, stored in physical material like floppy disk drives, hard disk drives, solid state drives, CDs, DVDs, and USB chips. Then the internet was invented, and centralized servers were made inexpensively and redundantly, and people could store their information in the "cloud". In many cases the cloud is free, or charges only a small fee. In exchange, the recipients agree to allow their personal information to be used to generate customized advertising targeted at them personally. But imagine their were a way for the cloud to earn interest on information much the same way banks earn interest on money, by synthesizing it and "lending it out". Since information is not rivalrous, this may prove viable with sufficient artificial intelligence aimed at developing ontologies and computer intelligence. The risk is the loss of privacy. Alternatively the customer pays the cloud for storage and computation, retaining privacy, in exchange being relieved of duties of backup, which when neglected lead to all too much data loss.

Once upon a time people kept their personal transportation near their person, parking cars and bikes at their homes, workplaces, or other destinations. This was the only way to guarantee point to point transportation in a timely way where densities were low, incomes high, and taxis scarce. Then "cloud commuting" was invented, cars from a giant pool operated by organizations in the cloud would dispatch a vehicle that drives to the customer on demand and in short order, and then deliver the customer to the destination. The vehicle would have the customers preferences pre-loaded (seat position, computing ability, audio environment). The customer benefits of course by not tying up capital in vehicles, nor having to worry about maintaining or fueling vehicles. The fleet is used more efficiently, each vehicle would operate 2 times or 3 times or more miles per year than current vehicles, so the fleet would turnover faster and be more modern. Fewer vehicles overall would be needed. It is likely customers would need to pay for this service (either as a subscription or a per-use basis), there is no obvious analogue to financial interest payments (and while advertising might offset some costs, surely it would not cover them). However stores might subsidize transportation, as might employers, as benefits for the customers or staff.

The tension between centralization and decentralization has been continuous through the history of technology, each has its advantages and disadvantages (and strangely, each also has religious zealots convinced there is one true way). This is ultimately a question of costs and benefits, and who bears the costs and benefits.

I am skeptical that cloud commuting can be made to work quite yet, there are still a few more technologies to perfect. Having tested Zipcar, their system lacks in several ways, much the ways the first banks failed frequently. Zipcars are still not local enough, they charge too much for lateness, the technology is still imperfect. But imagine we have cars that drive themselves. (and to PRT-advocates, these will be cars driving on streets, there are not enough resources to build a new infrastructure network for specialized vehicles). Smart cars solve the localness problem, since the cars come to you. In a way it also solves the lateness problem, because there is no need to reserve a specific car for a specific window, any unused fleet car can be dispatched. There would need to load balancing features, and maybe coordinated carpooling at peak times. (It also saves on parking, especially parking in high value areas).

Related links:

* Technological change, part 2: Autonomous vehicles

* The Future of Cars

August 16, 2008

The Slug Line automated

From "The Oil Drum" High-Tech Hitchhiking a proposal to automate what has been called "Casual Carpooling" or "Instant Carpooling", or Slugging. This is an idea the late Mel Webber at Berkeley had in principle, but now it seems the technologies are in place to execute.

One should also see the book Curb Rights to anticipate the problems this might generate.

July 27, 2008

Highway Linguistics

In The Washington Monthly, an interesting question about how highways are referred to by region: Highway Linguistics. A case for the Dictionary of American Regional English

July 25, 2008

Buses can increase property values

Buses can increase property values, so says this article in SFGate The Google Effect: How the company's shuttle line affects San Francisco real estate

Apparently Googlers will pay a premium to live in San Francisco and elsewhere near the Google Transit system. Will these rent price increases be capitalized in land is an outstanding question. (Anyone with Bay Area data want to run a Hedonic model?)

July 18, 2008

Is buying the wrong house a "weighting mistake"

Via Andrew Sullivan ... The Frontal Cortex : Buying the Wrong House

The post reports on a study that argues people overweight rare events (e.g. visitors to home) and underweight common ones (like commuting) and so buy larger houses farther away than they should.

The key paragraph from the original paper:
"Recently, one of us read a newspaper article that documented an interesting
example of what we may call a “weighting error?. When buying a house, one trade-off
people have to make is between the size of the house and the length of the daily commute
to work. Most people (note that the example comes from a Dutch newspaper) work in
city centers. As city centers are expensive, a preference for a short commute by necessity
means one is forced to buy a small house or apartment. Large houses are affordable, but
only for those who are willing to live in the countryside and to face a long commute. It
seems that many people think about this trade-off, and many eventually choose the large
house. After all, a third bathroom is very important for when grandma and grandpa come
over for Christmas, whereas driving two hours each day is really not that bad. Anecdotal
evidence has it that a lot of these people come to regret their choice. A third bathroom is
a completely superfluous asset for at least 362 or 363 days each year, whereas a long
commute does become a burden after a while. Recent evidence (Stutzer & Frey, 2007)
shows that people with longer commuting time report systematically lower subjective
well-being. "

July 3, 2008


An interesting article on elevators:
Taken for a Ride

From the article:
"According to statistical findings attached to the Energy Efficiency Act, which became law in 2006, 90 billion people each year ascend and descend on escalators, making it a more popular form of transportation than commercial airliners. The national energy use of escalators is estimated at 2.6 billion kilowatt hours per year, equivalent to powering 375,000 houses; its cost is roughly $260 million."

Well, $260M is less than $1/person in the US per year, not too bad all things considered.

I saw intermittent escalators deployed at the Zurich airport. Its a bit unnerving at first, you think the elevator isn't working, and then it starts just as you step on. Of course, in Switzerland, everything does just work, so why I would think it wasn't working is beyond me.

The article implies we should just climb stairs, which seems a bit hair-shirt wearing to me, given for less than 1/3 of a cent a day in variable cost, I get unlimited escalator rides. (My son insists on riding every escalator he sees, regardless of where it is going).

The number of escalators in the US = 30,000 ..., just over 2 for every McDonald's restaurant in the US (or one for every 10,000 people).

July 1, 2008

There are too many Starbucks

There are too many Starbucks, and Starbucks agrees ... Starbucks closing 600 stores in U.S. .

June 28, 2008

Machine Fecundity

From Kevin Kelly's blog: The Technium

"A while back George Dyson sent along this note about the fecundity of manufactured items:

I had to park my car at [Seattle's] SeaTac on Saturday-Sunday and this sparked a small epiphany. It now costs more to park a car at one airport than to rent one at the other end. To my twisted mind, this indicates that machines (taking the automobile as a benchmark) are now self-reproducing so fast we have reached a transition point where machines are cheaper than the empty space they fill."

June 18, 2008

Diffusion of Wal-Mart

An interesting paper on the spatial diffusion of Wal-Mart across the United States by Thomas Holmes: The Diffusion of Wal-Mart and Economies of Density


A YouTube Movie

June 15, 2008

Memo to the Next President of the United States on Transportation Policy

I have drafted a Memo to the Next President of the United States on Transportation Policy.

The memo outlines ten visions, which are summarized here, for fuller discussion, see the full memo:

  1. Within eight years more cars sold in the United States will be powered primarily by electricity and bio-fuels than by fossil fuels. All buses and passenger trains will use electricity or bio-fuels.
  2. Within eight years Americans will be able to ride autonomous smart cars that drive themselves in mixed traffic.
  3. Within a year, an independent federally-funded Bridge Inspection Service will begin to inspect and publicly report on the quality of all bridges on the National Highway System.
  4. After thorough evaluation, within eight years, bridges and pavements on the US Interstate Highway System will be upgraded to handle trucks carrying up to 100,000 pounds, increasing the efficiency of the trucking industry and by reducing the number of vehicle trips, increasing safety for other road users. These improvements will be paid for by the trucking industry, which directly benefits from the improved system. In heavily traveled corridors, a system of truck-only toll lanes will be constructed.
  5. Within eight years American travelers can choose to travel congestion-free by car or bus through America's largest metropolitan areas.
  6. Within four years American travelers will enter airports and transit, and train stations and cross borders, passing both security and immigration controls without delay while ensuring security.
  7. Within eight years a new source of transportation revenue based on time and place of use will be deployed, replacing the federal and state gas tax. This funding will support highway and transit networks.
  8. Returning to the vision of Democratic President Andrew Jackson, items in federal transportation legislation that do not serve a national purpose will be vetoed.
  9. Extending the bipartisan efforts of transportation deregulation in the late 1970s and early 1980s, within four years, highway and transit services and infrastructure will begin to be competitively provided by independent (public, private, or non-profit) organizations under appropriate local or federal oversight. Infrastructure will be provided under a public utility model, ensuring quality of service in exchange for earning a rate of return.
  10. Within one year, the United States federal government will establish separate capital and operating budgets. This will be coupled with a federal program to guarantee loans and bonds for highway and transit infrastructure projects.

  11. Full memo after the jump

    Continue reading "Memo to the Next President of the United States on Transportation Policy" »

June 7, 2008

People live within their space-time prism

From a Nature article, summarized in AP: Study secretly tracks cell phone users outside US

The gist was that about 3/4 people stay mostly within a 20 mile circle. This is largely the idea of the space-time prism developed by geographer Torsten Hagerstrand.

June 6, 2008

Comments on the Central Corridor

I have written a memo for the University of Minnesota administration outlining my views on the proposed Central Corridor, in particular its course through campus. This is based on my thoughts and a number of meetings with University of Minnesota staff, but reflects solely my own judgment. The download is about 10 MB in .pdf (it includes images).

Download file

Text after the jump (for figures, see the .pdf file above)

Continue reading "Comments on the Central Corridor" »

April 28, 2008

New Town Center for Columbia

An article from the Baltimore Sun: Town aims to redraw its core

One suspects the newspaper article above is not terribly accurate or complete ("Retail and arts space, and possibly an international center for the study of small cities, would front the roadway, replacing the office towers that ring the mall complex area." ... will office really be replaced by art, maybe complemented, but not replaced), but it appears the General Growth Properties plan, which has gone through many iterations, finally begins to account for the Mall as the centerpiece of downtown, and tie it in rather than keeping it separate.

The Howard County govt plan is here (pdf).

My previous posts on Columbia are here.

The meeting is tonight, alas it is not being webcast. The official website is here: Columbia Town Center

April 23, 2008

Does alcohol lubricate Putnam's social capital?

Minnesota ranks among worst in DWIs, study shows

"Minnesota has one of the nation's worst drunken driving rates, said a government report that says 15 percent of adult drivers nationally report driving under the influence of alcohol in the previous year. Here are the states with the worst records:

1. Wisconsin, 26.4 percent

2. North Dakota, 26.4 percent

3. Minnesota, 23.5 percent

4. Nebraska, 22.9 percent

5. South Dakota, 21.6 percent"

Note, these are also almost exactly the states with the highest social capital according to Robert Putnam's index (see the book Bowling Alone)

Table 4.1 Social capital scores by state
Rank State Score

1 North Dakota 1.712

2 South Dakota 1.693

3 Vermont 1.424

4 Minnesota 1.325

5 Montana 1.296

6 Nebraska 1.157

7 Iowa 0.988

8 New Hampshire 0.779

9 Wyoming 0.6710

10 Washington 0.6511

11 Wisconsin 0.5912

12 Oregon 0.57

(Source: Putnam 2000)
(Kevin Krizek and I discuss Putnam's social capital idea in the book Planning for Place and Plexus

This raises the interesting question: does alcohol lubricate Putnam's social capital?

From a social perspective, drinking alone at home may be better than drinking away from home. But what do I know, I am a teetotaler.

April 15, 2008

Housing + Transportation Affordability

Center for Neighborhood Technology: Housing + Transportation Affordability Index

An interesting idea, though I don't really buy the results, since housing as a percentage of income is a choice and there should not be a standard against which we judge this. If I choose to consume more house and less entertainment, who is to say that is "unaffordable". If housing + transport in the exurbs take a higher share of income than the cities, isn't that what the exurbanites prefer, and don't they get better houses than we city folk (i.e. likely to be new with all the amenities and more sq.ft. per person)?

April 10, 2008

Do Trash Cans Induce Garbage?

From the San Francisco papers a while back, I saw a headline ""City rids streets of hundreds of garbage cans: Mayor says high number led to trash overflows""

An article about this: Trash cans cut back on city streets / Mayor defends policy but supervisors, residents complain

On its face, eliminating garbage cans will not eliminate garbage, so what is the mental model Mayor Newsom has?

(a) by increasing the transportation cost of disposal, people will create less waste? (The induced demand argument.
(b) people/businesses are free-riding on public trash receptacles, and that by cutting back, people will fund their own receptacles?

The question needs to be asked why were public trash receptacles initially deployed? One suspects public dumping of waste and littering were problems, otherwise a solution would never have been proposed. Public dumping and littering are not mere aesthetic issues, there is also a significant public health problem. To sustain a large population in a small area, waste must be managed.

The example of Amsterdam may be worth visiting. Receptacles there are port-holes into a much large waste storage dumpster under the ground that is cleared every morning by giant mechanical cleaning machines in a fascinating example of advanced technology for seemingly mundane uses. This applies to recycling as well.

Continue reading "Do Trash Cans Induce Garbage?" »

March 28, 2008

Zero-Carbon City

From Fat Knowledge: World’s First Zero-Carbon City.

Masdar City, Abu Dhabi, UAE, recently broke ground, employing a design by noted architect Norman Foster. The aim in addition to being carbon neutral is to be zero-waste, applying advanced technologies in every infrastructure system.

Official Press Release:
The Masdar Initiative

And from the Inhabit Blog
Plans for Foster’s Masdar Carbon Neutral City Debut

The wikipedia article:
Masdar City

And finally: A Youtube

March 27, 2008

Houston, The Next Great World City?

An interesting article from Joel Kotkin: Lone Star Rising —
The American, A Magazine of Ideas

about Houston, Texas, a city whose airport I have visited, but otherwise I only know what I read.

Accessibility, Mobility and Density

Are accessibility and mobility complements or substitutes? I have a mental model a graph with a y-axis as density, and x-axis as mobility, where the Northeast corner would be high access: high density multiplied by high mobiilty.

This system behaves differently by modes. For transit, cities arrange themselves on a line from the southwest to the northeast (a positive feedback loop between supply and demand). For auto cities arrange on a line from the southeast to the northwest (a negative feedback loop between congestion and demand). Using data one could place specific cities on the graph. One expects places like New York and Hong Kong in the northeast corner, most US cities in the southeast corner, small developing-world cities without widespread adoption of modern automobile or transit technology in the southwest corner. Depending on where you draw the threshold, it is hard to see too many places in the upper northwest corner, as it would be difficult to grow to have high density without mobility. (Why would the city grow without the accessibility advantages?)

Density Mobility Tradeoff

Accessibility is a good, but it is not a good without costs, and there are limits to how much people are willing to pay for access. It may also suffer from diminishing returns, beyond a point each unit of accessibility is worth less and less. Places like Minneapolis have yet to reach that point, but surely there are places that have.

March 26, 2008

Weighted Density

Via Yglesias: Austin Contrarian: Density calculations for U.S. urbanized areas, weighted by census tract

The Census definitions are weighted by area, this is weighted by census track population, and produces a different, and some would say more intuitive result.

An interesting calculation, and goes back to the same issue regarding Observation Bias that comes up with transit ridership, although in this case, the observation bias may be weighting by area rather than population (so long as everything is properly defined).

March 17, 2008

Filling Up

In the column Filling Up , professional Blogger Matthew Yglesias talks about "Filling Up" the spaces around cities. "The problem issue the traffic which is bad everywhere anyone wants to be."

A solution Yglesias seems to miss: create places where people want to be elsewhere, i.e. if all the current good places are taken (and too expensive in terms of time and money), then create new good places where land is cheaper, either suburbs, satellite cities, or make other existing places "good". Economies of agglomeration, while they still exist, are clearly not what they used to be, and downtowns are far less important. Managing the positive feedback loop that are cities/real estate/accessibility is no easy trick, but it takes a special kind of elitism to think that "interesting places" (to use the term from Brad DeLong's post are inherently limited to a few large cities with long commute times.

(full quote "The filling-up of America so that you can no longer build a detached single-family house within half-an-hour's driving time of the interesting places people want to be, and the consequent rise both in current location premia and expected future location premia")

This Census Bureau Table gives commute times in large cities in the United States. In short, only three cities had an average over 30 minutes (New York, Chicago, and Philadelphia) though another few come close (Go Baltimore!). As a Baltimore native, I take pride we almost make DeLong's list of interesting places, but I am sure I could find reasonably priced housing within 30 minutes of downtown if I wanted to.

February 17, 2008

Open Street Map

Open Street Map is a project to have an open source street map of the world created by users. View a Historic animation of their progress.

Clearly the past few months have seen the addition of official databases (especially the US Tiger file). It is interesting how similar this growth is to wikipedia, which was organic, until Rambot started posting official Census data, vastly increasing the US geographic coverage of the encyclopedia, and then resumed its organic pace.

November 8, 2007

Just-in-time consumption: Does the `pint of milk test' hold water?

Growth of international trade indicates society has not entered an age of "dematerialization" as has been debated. [Herman et al., 1990,Wernick et al., 1996,Heiskanen and Jalas, 2000] While individual objects may be getting smaller, consumers have been steadily acquiring more objects. This paper explores where that acquisition occurs.

Just-in-time production revolutionized manufacturing, enabling both a reduction in inventories as supplies arrive only shortly before needed, and an improvement in quality as poorly made inputs are no longer stored for long periods of time, but can be quickly identified and feedback provided to the supplier. The widespread adoption of the just-in-time process is itself the product of the logistics revolution, information and communications technologies, containerization in shipping, and the interstate highway system. It has seen a concomitant change in the retail sector, which has brought about fewer and larger stores at a greater distance from the end consumer.
The notion of just-in-time consumption has not received the same attention as just-in-time production. The phrase itself, though seemingly a natural mirror to the more widely used "just-in-time production" only generates 821 hits in Google, of which only a few are on-point, in comparison to over 153,000 for "just-in-time production". 2
Yet many goods and services are already consumed in a just-in-time manner. Most notable is energy, which is delivered on-demand to users, who no longer store coal at home for the furnace, but instead buy natural gas or electricity as needed. (The slowly vanishing home heating oil remains an exception). Other services that are provided on-demand or just-in-time include water and sewer, communications (both telephony and television). What is in common about these disparate technologies is their network nature, the large infrastructure required to enable using the flows on-demand. While sewer is a continuous service for most people (those who do not have septic tanks), garbage is typically only collected periodically (e.g. once a week), and recycling less so (e.g. fortnightly).
Other goods once saw regular to-the-house delivery, especially in suburban areas. Foxell [2005] writes of goods and services found in Metro-land, the idyllic north London suburbs built by the Metropolitan railway in the early twentieth century "This service economy is illustrated by the variety of tradesmen that called at our home: the milkman twice a day, with a horse-drawn cart; the baker once a day, with a large upright barrow on two wheels, the handles of which lifted him off the ground when going down hill; the postman thrice; the butcherÕs boy by bicycle twice a week; and the grocer twice a week. Others like the coalman or the Gas, Light & Coke Co. in their steam-powered Sentinel lorry also made regular deliveries. Over a longer period, visits could be expected from the men from the Prudential [insurance], Hoover [vacuum cleaners], Singer [sewing machines] and the like ∆ all using a service call to take the opportunity to sell new products. There was something reassuring about seeing such familiar faces and catching up with the latest gossip. In addition there were the itinerant callers such as Walls Ice Cream man on his tricycle as well as the French onion sellers, gypsies with pegs and posies, rag and bone men, tinkers [metalsmiths] and the knife-sharpeners with their pedal-driving grinding wheels."
Today, the vast majority of those goods are not acquired at home but in stores or online. Delivery services have replaced salesmen, as the two functions (delivery and sales) are now distinct and specialized. Today's visitors might be the post office, FedEx or UPS, and the pizza delivery boy.
Just-in-time does not require delivery to the residence, it can involve ubiquity in the placement of stores, so that they are near the end consumer. Traditionally the retail store was just that, a place where a community could store goods, and individuals could take or buy them as needed.
Many planners would like to make the ability to acquire goods just-in-time without the use of a vehicle a normative planning standard. For instance, a report, Beyond 2010: A Holistic Approach to Road Safety in Great Britain calls for the "pint of milk test", for all new developments, whereby a resident can get to a shop to buy a pint of milk in 10 minutes or less without getting in their car [Parliamentary Advisory Council on Transport Safety, 2007]. The idea of 10 minutes comes from people's willingness to walk, people are less willing to walk longer distances than shorter, and 10 minutes (or one-half mile (0.8 km)) seems to be a threshold over which walking tolerance seems to drop. This distance was derived from several empirical studies, including Pushkarev and Zupan [n.d.], who showed the median walk by travelers accessing the New York subway was 0.35 mi (0.57 km), while the median walk to access commuter rail stations in suburban New Jersey was 0.5 to 0.6 mi (0.8 - 1.0 km). Results from the 1983/84 National Personal Transportation Survey reported by Unterman [1990] found shorter distances: 70 percent of Americans will walk 500 feet (0.15 km) for normal daily trips, 40 percent walk 1,000 feet (0.31 km), and only 10 percent walk a half-mile (0.8 km).
The pint of milk refers to a standard quantity of a highly perishable and frequently consumed good. The objective of avoiding car use is obvious for a group advocating road safety. The pint of milk test has received some currency in England, being noted by several studies in recent years [Bennett and Morris, 2006,Marsh, 2004]. This is a particular issue in a crowded city like London, where auto ownership is lower than suburban areas, roads are more crowded, and parking more difficult even for those with a car.
The trends in retailing have been clear in the United States for a long time. Stores are getting larger and gaining larger market areas [Yim, 1990]. Small stores serving local areas have been losing market share to larger stores which bring with them economies of scale. Efforts to reverse this trend have met with resistance from retailers, consumers, and neighbors [Nelson and Niles, 1999].
Illustrating this trend, the Food Marketing Institute reports in 2006 there were 34,019 supermarkets (with $2 million in sales or more, noting the median annual sales for a supermarket was $17 million, and average size was 48,705 sq. ft. ( m2)). The average number of trips per week consumers make to the supermarket was 1.9. 3
In 1930, The Great Atlantic and Pacific Tea Company, at the time the leading US supermarket, alone had 16,000 stores with a combined revenue of $1 billion (or per store revenue of $62,500 in 1930 dollars, estimated to be $754,000 today) 4 [The Rise and Decline of the Great Atlantic and Pacific Tea company, n.d.]
Handy [1993] claims "the automobile instigated a collapse of the retail hierarchy by encouraging the growth of community and regional centers at the expense of local shops and the central business district. The result has been a cycle of dependence, in which suburban communities are designed for the automobile leaving residents little choice but to drive."
As with stores, houses too are getting larger. New suburban homes have more space to store goods in-house. While urban residents export storage to common stores, suburban residents more likely to have second freezers, have more space to store stuff.
While the number of freezers per household in the United States is declining as second freezers are being retired and not replaced, the number of refrigerators is increasing slightly, due to households obtaining second refrigerators. [Wenzel et al., 1997]. While no immediate inference can be made about this, other trends are also at work. Total refrigerated and frozen space has not been computed, though the average size of a house's primary refrigerator or freezer is likely increasing. Food may last longer in refrigerators than it used to due to the addition of preservatives (though the trend of increased consumption of organic foods may reverse this). Further globalization may mean that fewer goods are seasonal and need to be accumulated prior to their being out-of-season.
Persson and Bratt [2001] note that e-shopping may induce the installation of a second set of fridge/freezers per household to receive delivered goods. This additional electricity consumption has environmental consequences; already, there are 2.2 refrigerators and freezers per household in New Zealand (Roke, 2006) cited in [New Zealand Ministry for the Environment, n.d.].
If urban residents do undertake more just-in-time consumption than suburbanites both because of the higher storage costs associated with smaller houses, and the greater opportunity afforded by more stores nearby, we would expect to see this show up in the travel behavior data that is collected by urban regions.
Minneapolis St. Paul Remainder of Hennepin County
Year Structure Built 1926 1929 1970
Sq. Ft. 1773 1826 2152
Sq. Ft. per Person 822 755 810
Households with No Cars 5900 2800 2500
Table 1 illustrates some of the differences between the City of Minneapolis, suburban Hennepin County (Hennepin excluding the City of Minneapolis), and the City of St. Paul in neighboring Ramsey County. Residents of Minneapolis live in older houses (average year built of 1926 vs. 1970 in the suburbs) with 1773 square feet vs. 2152 in the suburbs. However because of the lower household size, city residents actually have slightly more area per person. Further Minneapolis residents are more likely to be carless.
According to the 2000/2001 Twin Cities Travel Behavior Inventory among residents of the City of Minneapolis, 12.8 percent of daily trips were for shopping 5 while for Hennepin County excluding the City of Minneapolis the number was 12.2 percent 6. Thus Minneapolitans devote 5 percent more of their trips to shopping than suburban Hennepin County residents.
Minneapolitans also make slightly more trips than their suburban brethren, 3.81 per day vs. 3.70 for suburban Hennepin. Unfortunately, it is difficult to ascertain whether total trip making is rising because of differences in survey methodology over time, though one expects it is. 7. Given the small differences and their temporal instability, it probably is unreasonable to make much of them
The evidence weakly supports the hypothesis that city residents who have somewhat higher accessibility to neighborhood stores and somewhat reduced storage space at home shop more frequently.
Broadly, there are two types of places, those that satisfy the pint of milk test, and those that don't. Similarly, there are two kinds of people, those who care about the pint of milk test and those who don't. The problem comes from the mismatch of those who care but live in places that are unsatisfactory. (Those who don't care but live in places passing the test are probably okay). If self-selection is at work, these cells are not randomly distributed, but people who want to live in particular environments do so. People who prefer milk-accessible areas bid up prices in those areas, while those who are indifferent (or perhaps lactose-intolerant) move out. However, if preferences change faster than spatial structure, there may be a mismatch. Policy that excludes mixture of residential and commercial development may also foster a mismatch.
Evidence from the Twin Cities bears on the issue (Figures 1 to 4). According to the American Housing Survey [US Census Bureau, n.d.], over 80 percent of residents in the City of Minneapolis report satisfactory neighborhood shopping within a mile of home, compared with 70 percent of those in suburban Hennepin County (Figure 1). Despite that positive assessment of shopping, suburban Hennepin residents have a better opinion of their own neighborhood than those in the City of Minneapolis (Figure 2). The problems these urbanites report in greater numbers than their suburban counterparts are noise and traffic, crime, and odors (Figure 3).
When people move, they are doing so to places they believe are better, but for all residents it is the home that is better than previous much more so than the neighborhood, and in Minneapolis, only a third rate their current neighborhood as better than their previous (in contrast to half of suburban residents) (Figure 4).
To the extent neighborhood shopping enabling just-in-time consumption of the pint of milk is important to people, cities fare better than their suburbs, but if the cost of that neighborhood shopping is other urban ills, people will make the trade-off, sacrificing access to retail to have access to quite and congestion free, safe, and pleasantly smelling suburban environments.
Whether this is a social good is another question entirely, and depends on relative efficiency of urban goods delivery services, energy efficiency of in-store displays vs. at-home refrigeration units, and numerous other questions.


Bennett, J.  Morris, J. 2006 , Gateway people, Technical report, Institute for Public Policy Research.
Foxell, C. 2005 , Rails to Metro-Land., Clive Foxell, Chesham, Bucks, England.
Handy, S. 1993 , "A Cycle of Dependence: Automobiles, Accessibility, and the Evolution of the Transportation and Retail Hierarchies", Berkeley Planning Journal , Vol. 8, pp. 21-43.
Heiskanen, E.  Jalas, M. 2000 , Dematerialization Through Services: A Review and Evaluation of the Debate, Ministry of Environment: Edita, jakaja.
Herman, R., Ardekani, S.  Ausubel, J. 1990 , "Dematerialization", Technological Forecasting and Social Change , Vol. 38(3), pp. 333-347.
Marsh, G. 2004 , "Tesco piles 'em high: Flats above supermarkets are a good buy", The Times , Vol. June 18, 2004.
Nelson, D.  Niles, J. 1999 , "Market Dynamics and Nonwork Travel Patterns; Obstacles to Transit-Oriented Development?", Transportation Research Record , Vol. 1669, Transportation Research Board of the National Academies, pp. 13-21.
New Zealand Ministry for the Environment n.d. , Technical report.
Parliamentary Advisory Council on Transport Safety 2007 , Beyond 2010: A Holistic Approach to Road Safety in Great Britain, Technical report, Parliamentary Advisory Council on Transport Safety. Parliamentary Advisory Council for Transport Safety
Persson, A.  Bratt, M. 2001 , "Future CO 2 savings from on-line shopping jeopardised by bad planning", Proceedings of the 2001 ECEEE Summer Study ÔFurther than Ever from Kyoto .
Pushkarev, B.  Zupan, J. n.d. , "Where Transit Works: Urban Densities for Public Transportation", Urban Transportation: Perspectives and Prospects , pp. 341-344.
The Rise and Decline of the Great Atlantic and Pacific Tea company n.d. .
Unterman, D. 1990 , `Accommodating the Pedestrian: Adapting Towns and Neighborhoods for Walking and Bicycling. Personal Travel in the US, Vol. II: A Report of the Findings from 1983-1984 NPTS, Source Control Programs'.
US Census Bureau n.d. , American Housing Survey for the Minneapolis St. Paul Metropolitan Area, Technical report, US Census Bureau. 1998AHS: Minneapolis h170-98-9.
Wenzel, T., Koomey, J., Rosenquist, G., Sanchez, M.  Hanford, J. 1997 , "Energy Data Sourcebook for the US Residential Sector", Lawrence Berkeley National Laboratory, Report , Vol. 40297.
Wernick, I., Herman, R., Govind, S.  Ausubel, J. 1996 , "Materialization and Dematerialization: Measures and Trends.", Daedalus , Vol. 125(3), American Academy of Arts and Sciences.
Yim, Y. 1990 , The Relationship Between Transportation Services and Urban Activities: The Food Retail Distribution Case, PhD thesis, University of California, Institute of Transportation Studies.

Figure 1 Satisfactory Shopping Figure 2 Opinion of Neighborhood Figure 3 Urban Problems Figure 4 Comparison


1David Levinson is RP Braun-CTS Chair of Transportation Engineering; Director of Network, Economics, and Urban Systems Research Group; University of Minnesota, Department of Civil Engineering, 500 Pillsbury Drive SE, Minneapolis, MN 55455 USA, Email:, web:
2By just-in-time consumption, I mean acquisition of a good by the end consumer shortly before its use, rather than being acquired and stored for future use.
3 (now offline and found in Google cache; Sources: U.S. Department of Labor, U.S. Department of Agriculture, Progressive Grocer magazine, U.S. Census Bureau, and Food Marketing Institute
4Conversion factor from Samuel H. Williamson, "Five Ways to Compute the Relative Value of a U.S. Dollar Amount, 1790 - 2006," http://MeasuringWorth.Com, 2007. Alternative conversions include:
  • $754,491.02 using the Consumer Price Index

  • $631,644.95 using the GDP deflator

  • $2,355,247.64 using the unskilled wage

  • $3,715,127.08 using the nominal GDP per capita

  • $9,042,420.50 using the relative share of GDP

52,223 shopping trips, 17,353 total trips (4555 people)
6828 shopping trips, 6785 total trips) (1830 people)
7Calculations using the 1990 TBI indicates that Minneapolitans reported on average 4.70 trips per person in 1990, while suburban Hennepin residents reported 4.85 per person

File translated from TEX by TTH, version 3.38.
On 8 Nov 2007, 16:59.

November 7, 2007

Causes of Death Are Linked to a Person’s Weight

From the NYT: Causes of Death Are Linked to a Person's Weight

"Linking, for the first time, causes of death to specific weights, they report that overweight people have a lower death rate because they are much less likely to die from a grab bag of diseases that includes Alzheimer’s and Parkinson’s, infections and lung disease. And that lower risk is not counteracted by increased risks of dying from any other disease, including cancer, diabetes or heart disease."

So if suburbs cause obesity, and obesity reduces the death rate overall, then suburbs are good and cities bad for public health.

August 14, 2007

Antecedents of Urban Sprawl

From LA Times: Angkor was a city ahead of its time .. the city had of about a million people spread over an area similar to LA before the industrial revolution.

July 13, 2007

The Spontaneous City

The Spontaneous City

The Wiktionary (the dictionary counterpart to Wikipedia) says that the word "spontaneous" derives from the late Latin word "spontaneus", from Latin "sponte" meaning "of one's free will, voluntarily". That meaning still holds, but the word has acquired an additional meaning, acting "without planning". Planning in contrast is "the act of formulating a course of action" or drawing up "a set of intended actions, though which one expects to achieve a goal". The words are not strictly antonyms, but they are very far from synonyms. To act spontaneously requires there be no specific forethought, to plan imposes structure and intention upon action.

When I was younger I worked in Silver Spring, Maryland at the Maryland-National Capital Park and Planning Commission - Montgomery County Planning Department (MNCPPC-MCPD). While there I worked on a number of plans and policies, most notably the Annual Growth Policy (AGP) which aimed to regulate the pace of development, and by regulating pace differently in different areas, it also affected the sequence of development. The AGP did not intend to affect the ultimate development of an area, that was left for the plan.

There were a number of flaws with the AGP, but one I thought most important was the attempt to pro-actively anticipate the future rather than responding to decisions. The AGP established "staging ceilings" for each area of the county (about 30 or so), the was the maximum number of jobs and housing units permitted in that area, so that public facilities would be adequate. One fundamental difficulty was that the optimal number for one area depended on what actually happened in other areas, which of course was unknown until that development actually occurred. Thus the staging ceilings in one area were conditioned upon ceilings in another area, that may or may not have been exceeded (there were lots of ways ceilings could be exceeded, but if the ceiling were exceeded, the area was placed in moratorium for new development).

This experience, contemporaneous with the fall of Communism, shattered my naive beliefs about planning, and along with reading Hayek's The Fatal Conceit, it also shattered what I had not thought deeply about in terms of the problems of forecasting. Growing up in the 1980s I had some belief in markets, clearly the economy was doing better in the unregulated Reagan years than in the 1970s. Yet I also understood there were market imperfections, externalities, and public goods that an unregulated market just did not properly account for.

I had grown up in Columbia, Maryland, a highly planned new city from the 1960s, and clearly I was constantly reminded in the promotional literature, it was a better place to live with fewer problems than unplanned sprawling suburbs or the decaying inner city. One of the main critiques of Columbia was its sterility, its lack of life. Things were not out of place there, there were no non-conforming uses.

Could one plan without planning?

The first notion I had while at MNCPPC-MCPD was the idea of just-in-time or dynamic planning. Instead of trying to proactively predict the future, could we just respond to market proposals with a yea or nay (and other feedback). If the proposal met standards, it would go forward, if not, it would be rejected. The standards would not be site specific, but instead be geared toward assessing things public agencies should be concerned about, namely ensuring public facilities remained adequate. I was thinking mainly about replacing the AGP growth management system, rules about zoning and so on were not really in my purview. This was really more like dynamic regulating than dynamic planning.

The difficulty raised with this is that it reduces certainty for private-sector actors, who under the AGP at least knew in advance whether public facilities were adequate. Certainty is not the only value on which a public policy should be judged, I could establish certainty by prohibiting all development, and that would not be good for the private-sector either. Further, developers who have already been approved might like the idea that their competitors cannot go forward because all of the available infrastructure capacity has already been committed.

The second notion came later, while a graduate student at the University of California, Berkeley, as a way to replace zoning. The the role of the public is to establish a vision for the future, and the role of public servants is to facilitate and enable that vision. The vision is not generally site-specific but vague. Development would be judged by whether they moved toward the vision or against it. No plan would be written, no zoning enacted, only the vision would be expressed.

This decreases certainty even more. But it challenges developers to achieve consensus with the neighbors of potential projects.

After teaching a transportation-land use course at the University of Minnesota for a few years, I stumbled upon a third notion. This was to challenge the core tenet that planning actually creates better places.

What does one want from a place?

One thing I want is vibe or vibrant communities. I also want the ability to do what I want when I want. This I will call "spontaneous action". Spontaneous action requires at least two elements.

The first is the presence of things I want to do. This presence is both spatial and temporal. The thing must be where I want it to be, and it must be open or available when I want to use it.

The second is the ability to reach those things when I want to. I need to have a means of transporting myself conveniently from where I am to where I want to be when I want to go there. There must be both destinations and networks that satisfy action.

There are many locations that have networks, and people who have vehicles, that allow them to move about easily. In any small town or rural community, someone who has a car can easily move about, but there is nowhere to go. These areas have high mobility.

Some places have lots of activity. Cities in general have high density. However because of crowding it may be difficult to move around very much, these places may be congested, limiting the speed and comfort of travel.

In the best places, there are lots of places to go and things to do, and the network is constructed with appropriate differentiation so that are fast links connecting dense places. The net is that even if one can reach things faster than in a small town, because the slow speed is compensated for by the short distance and the relatively high speed links, these areas have high accessibility.

Different people want different things. If we all wanted the same things, life would be pretty boring. Still accessibility is something that many people do want.

Places with higher accessibility allow more spontaneous action than places with lower accessibility. Land prices are higher in places with high accessibility both because of the scarcity of such places and their value.

There is a premium to be paid for "spontaneous action", an option value that people hold, even if they never go to a show, or a game, or the museum, or the particular specialist shop (the bookstore specializing in gambling books I found in London e.g.), the accessibility gives them the option of engaging in that activity.

(As used here, spontaneous action is limited to what others are willing to allow or accommodate. There are many things for technical or economic reasons I cannot acquire and many activities I cannot engage in because they do not exist).

The opposite of spontaneous action is scheduled action. If I cannot engage in things when I want, I must plan in advance when to do them. This may be because of other people's constraints, or limitations to the transportation system, or hours of business of the thing I seek. The advantage of a large city is the increased flexibility, the high frequency of transit services, and the increased likelihood of finding a 24-hour store specializing in what you seek (London notwithstanding

Spontaneous development

Land use planning emerged for a reason, it was a response to the negative features of unplanned, uncontrolled development. Some people did things, like build quarries, that really upset their neighbors. The "nuisance" lawsuit was thought to be insufficient, and quite reactive, would it be possible to proactively avoid this problem? Zoning was one response. Zoning would implement plans, and provide "visions" for individual parcels. It provided certainty at the cost of flexibility. It also capped density in many places, perhaps below where the market density would have been. (It is very difficult to do counter-factual analyses of something like this, and the extent to which zoned density exceeds actual density we can say that the market requirements were lower than the zoning, but when the actual density equals the zoned density, the market desires were probably greater than that permitted, but by how much is impossible to say with certainty).

Zoning is not a requirement of today's cities, Houston, Texas is often pitched as A city without zoning , though there are contractual covenants and other private equivalents of zoning in many areas of the city. Moreover, the city has numerous other regulations affecting land use.

Spontaneous development would still need to respect property rights and rule of law, though the law would be more limited than found in many places today.

Does planning lead to more or less spontaneous action?

Can we plan and regulate cities to achieve more spontaneous action than an unplanned city?

Presently, that question must remain a question, the question of "can we plan" is very different than "do we plan".

We can think of a graph with two-axes.

On the x-axis we have degree of spontaneous action, with the zero point marking a totalitarian city under siege with a curfew imposed, and the right point complete freedom to consume whatever the market can produce.

On the y-axis we have degree of spontaneous development, with the zero point marking a pre-planned communist state and the topmost point complete freedom to develop. The question is, what is the shape of the curve? Does spontaneous development enhance or constrain spontaneous action? Is there any relation?

Degree of Spontaneous Development
0--------------------------------- Degree of Spontaneous Action
0 high

Spontaneity in a can

One of the features of modern planning is the attempt to provide vibe and spontaneity in the urban environment. The festival marketplace is a classic example. If only we can create an exciting, but controlled atmosphere, then we will have achieved the best of spontaneously arisen places without their defects. The market for these festival marketplaces has been mixed though. For every success like Baltimore's Harborplace, there is a failure like Minneapolis's St. Anthony Main. The very regulation that aims to limit the negative effects minimizes the spontaneity to the point of failure.

Unlike SPAM, vibrant spontaneity does not come in a can, it is not some formulaic easily reproducible phenomenon.


There are numerous interesting examples one could look at.

There are various types of places which involve different types of planning by non-governmental agents:

Event City - Fairs, Festivals, Shows, Conventions, Sports

Enveloped City - Skyways, Subways, and Shopping Malls

Planned City - Columbia

In addition one could compare cities/places that have various degrees of land use control and various degrees of spontaneous action. New York has a high degree of spontaneous action, and probably once had a high degree of spontaneous development (though this was on a pre-specified grid network). Many developing cities still have spontaneous development to the consternation of city officials, though the alternative might be no development at all.

We also need measurements of spontaneous action. Travel and activity surveys tend to ask what was done, but not about what wasn't done, or how long the activity was planned for. A new type of data gathering instrument is required to fully assess the question. Do people in large cities spend more or less time planning their actions? How far in advance do they plan? (there is some research on this to be sure, but nothing I am aware of allows inter-metropolitan comparisons. We can look at the number of trips made, but that is only a partial indicator, because many trips have substitutes, we need to determine the quality of those trips as well.

References Levinson, David (1997) The Limits to Growth Management. Environment and Planning B: Planning and Design 24: 689-707 Levinson, David (2003) The Next America Revisited Journal of Planning Education and Research Summer 2003, Volume 22, Number 4, pp. 329-345. Hayek, Friedrich (1988) The Fatal Conceit: The Errors of Socialism. The University of Chicago

June 10, 2007

A success we should build on

The London Green Belt has been in place since just before World War II when Patrick Abercrombie's study recommended establishing a ring around the city which would remain unsuburbanized (one hesitates to say undeveloped, as farms are there). Now with the housing shortage, people are again suggesting the Green Belt is "a success we should build on":

Build on the green belt, and build now-Comment-Columnists-Minette Marrin-TimesOnline

Back in the day, the solution was to build new towns outside the Green Belt. Gordon Brown is proposing more of these. Towns like Welwyn and Letchworth were built as Garden Cities by Ebenezer Howard, and, but, by design are relatively small (on the order of 33,000 residents for Letchworth, 55,000 for Welwyn Garden City). From my visits, they seem excellent places to live, though the scale may be slightly off outside the town center (the residential density is a bit low, creating excessive walking distances).

Stevenge, (population 80,000) a post-war new town, (built on a much older town) is very much like Columbia, with large elements of Radburn, many pedestrian tunnels to access the town center and train station. There are also traffic roundabouts everywhere, so cars need not stop at signals. I felt like I grew up here.

Milton Keynes (population 185,000) on the other hand is much larger, but terribly overscaled, with large gaps between the residential and downtown areas. This creates opportunites for infill, but in the meantime there is an excessive amount of surface parking in the town center. Unlike the other towns I named above, the shopping mall (the largest single level mall in the world?) is disconnected from the train station.

Despite its imperfections, this model of new towns has a number of advantages over just adding another suburb in the Green Belt. They provide (or at least can provide) a coherent center and place. By increasing "surface area" they reduce the distance between people and the countryside. Every development in the Green Belt makes existing Londers that much farther from the country.

Now, one might suggest if the Green Belt is to be preserved, it should be done the right way, by buying the land (or development rights), rather than by fiat or regulations. This certainly seems a better way of controlling the use of land if property rights are to be respected. But the point here isn't about the mechanics of how land should be preserved, but about what constitutes a better urban form

A) A giant unbroken conurbation where rings of development are fully contiguous


B) A large conurbation with satellite cities.

The latter, while it might increase average distance to the center, decreases distance to the edge. It also provides more variety and differentiation of the bundle of attributes that we call property.

Perhaps the market should decide, but the market fails in providing numerous public goods (access to the countryside being an example), as some things are very difficult to establish easily enforceable rights for.

June 9, 2007

Simulating Skyways

Two new movies/simulations of the co-evolution of downtown Minneapolis and its skyways system have been postedhere

These are large movies (132 and 137 MB), so be forewarned.

These are based on research done by Michael Corbett as part of his MS classwork and Feng Xie as part of his PhD. The research paper underlying this can be found:
Evolution of the Second-Story City: Modeling the Growth of the Minneapolis
Skyway Network
to be presented at the upcoming World Conference on Transport Research in Berkeley.

March 3, 2007

The Co-Evolution of London's Land Use and Transport

updated August 25, 2009:

For those of you who doubt I am doing work over in London, I have completed two other papers (in addition to "Too Expensive to Meter" based on my research over here):

  • Levinson, David (2008) The Orderliness Hypothesis: Does Population Density Explain the Sequence of Rail Station Opening in London? Journal of Transport History 29(1) March 2008 pp.98-114.[download]
  • Network growth is a complex phenomenon. Some have suggested that it occurs in an orderly or rational way, based on the size of the places that are connected. David Levinson examines the order in which stations were added to the London surface rail and Underground rail networks in the nineteenth and twentieth centuries, testing the extent to which order correlates with population density. While population density is an important factor in explaining order, he shows that other factors were at work. The network itself helps to reshape land uses, and a network that may have been well ordered at one time may drift away from order as activities relocate.

  • Levinson, David (2008) Density and Dispersion: The Co-Development of Land use and Rail in London. Journal of Economic Geography 8(1) 55-57.
    JEG: [doi]
  • This article examines the changes that occurred in the rail network and density of population in London during the 19th and 20th centuries. It aims to disentangle the 'chicken and egg' problem of which came first, network or land development, through a set of statistical analyses clearly distinguishing events by order. Using panel data representing the 33 boroughs of London over each decade from 1871 to 2001, the research finds that there is a positive feedback effect between population density and network density. Additional rail stations (either Underground or surface) are positive factors leading to subsequent increases in population in the suburbs of London, while additional population density is a factor in subsequently deploying more rail. These effects differ in central London, where the additional accessibility produced by rail led to commercial development and concomitant depopulation. There are also differences in the effects associated with surface rail stations and Underground stations, as the Underground was able to get into central London in a way that surface rail could not. However, the two networks were weak (and statistically insignificant) substitutes for each other in the suburbs, while the density of surface rail stations was a complement to the Underground in the center, though not vice versa.

Perhaps more interesting for the non-academic, we (Ahmed El-Geneidy, Feng Xie, and myself of the Nexus group) have put together three quicktime movies

  • 1.The co-evolution of London population density and surface (National) rail

  • 2.The co-evolution of London population density and the Underground

  • 3.The co-evolution of London population density and surface (National) rail and the Underground

These can be accessed from here.

January 30, 2007

Prison overcrowding is just a queueing problem

According to an article from 5 years ago, BBC NEWS | UK | Prison overcrowding 'at crisis point'. Apparently it still is: BBC NEWS | UK | UK Politics | Jail system in 'serious crisis'.

This "perpetual crisis" is simply a queueing problem: There is an arrival rate of prisoners (how many people we jail), there is a departure rate (how many people we release), and there is a storage capacity (how many we keep behind bars). To relieve this perpetual crisis, we can
1) reduce arrivals
2) increase departures
3) increase storage, either by adding capacity or making better use of the space through double or triple bedding.

The various strategies have been tried, reducing arrivals most notably last week when the beleagured Home Secretary (Attorney General/Secretary of Homeland Security more or less for US readers) was chastised by a judge who refused to jail a paedophile because of a memo from the Home Office about prison crowding.

Capacity will take some time to expand, especially given the inaction to date.

We could increase departures, but then prisoners would not serve their full sentences (and we know that prisoners who are safe to release after 7 years must somehow remain very dangerous after 6 years and 364 days).

The problem in thinking about this is the implicit (and wrong) assumption of inelasticity of demand, if we changed the cost, we would get just as many prisoners.

So how about pricing? Charging prisoners for their stay would probably not work, most can't afford it, and we would have to send them to debtor's prison.

Maybe we could charge someone else.

Prison cells are a scarce commodity, valuable to the communities seeking to send more of their own into the slammer. Each community (via their judges) would administer a "prison budget". The judges could bid on cells in an auction (envision eBay), perhaps a Dutch auction, for each of their potential prisoners, the highest N bidders get to imprison their least favorite baddies. There would of course be different classes of prison cells, and a certain number enter the market each week (e.g. 5 cells of maximum security with a 6 year stay, 19 cells of medium security for a 3 year stay). We might even get an options market, and trading between communities if the match didn't work. Prisons could transform security levels to better match market demand. It shouldn't take too long for a new equilibrium to emerge.

This might open up the option for new suppliers to enter the market, driving down costs. I don't know the legal nicities of this over here in the UK, but in the US many states have private prisons, and one could easily see the least dangerous baddies condemned to an underperforming Motel 6 instead of prison.

Communities would reveal through this process which crimes they really dislike based on how much they are willing to pay to imprison different people who committed different crimes.

Just a thought.

December 20, 2006

Security is the enemy of efficiency, or attention is a scarce resource

"Security is the enemy of efficiency". I don't know if anyone has said it before, but it has become clear to me that the primary outcome of most security systems is to make my (and others') life less productive. Whether I am safer as a result I have no evidence to produce.

Continue reading "Security is the enemy of efficiency, or attention is a scarce resource" »

June 18, 2006

Dispersing jobs: good or bad?

This article: Region's Job Growth a Centrifugal Force starts badly "As a consensus builds that the Washington region needs to concentrate job growth, there are signs that the exact opposite is happening." and gets worse.

Continue reading "Dispersing jobs: good or bad?" »