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September 10, 2009

The Economics of Road Network Ownership: An Agent-Based Approach - International Journal of Sustainable Transportation

Recently published:

Zhang, Lei and David Levinson (2009) The Economics of Road Network Ownership: An Agent-Based Approach. International Journal of Sustainable Transport Sept. 2009 3(5) pp. 339-359. [doi]

This paper explores the economic impact of alternative ownership structures on transportation system performance, social welfare, and regulatory needs. Road pricing, investment, and ownership decisions are jointly considered in an agent-based evolutionary model applicable to large networks. Results suggest that a centralized public regime with average-cost pricing is far from socially optimal with even moderate demand growth. When properly regulated, a completely privatized transportation network could achieve net social benefits close to the theoretical optimum and distribute a high percentage of welfare gains to travelers. But an unregulated private road economy would suffer from higher-than-optimal tolls and overinvestment.

Keywords: network economics; privatization; road pricing; simulation of network evolution; transportation financing


August 29, 2009

Investing for Reliability and Security in Transportation Networks

Recently published:

Zhang, Lei, and David M. Levinson (2008) Investing for Reliability and Security in Transportation Networks. Transportation Research Record: Journal of the Transportation Research Board #2041 pp.1-10 [doi]

Alternative transportation investment policies can lead to very different network forms in the future. The desirability of a transportation network should be assessed not only by its economic efficiency but also reliability, because the cost of incidental capacity loss in a road network can be massive. This research concerns how investment rules shape the hierarchical structure of roads, and affects network fragility with regard to natural disasters, congestion, and accidents and vulnerability to targeted attacks. A microscopic network growth model predicts the equilibrium road networks under two alternative policy scenarios: investment based on benefit cost analysis or bottleneck removal. A set of Monte-Carlo simulation runs, in which a certain percentage of links are removed according to the type of network degradation analyzed, are carried out to evaluate the equilibrium road networks. It is found that hierarchy exists in road networks for reasons such as economic efficiency, but an overly hierarchical structure has serious reliability problems. Throughout the equilibrating or evolution process, the studied grid network under benefit cost analysis has better efficiency performance, as well as error and attack tolerance. The policy implication from these findings is that benefit-cost analysis should be preferred to myopic bottleneck-removal type of investment rules, no matter how the planning horizon is specified.

Keywords: Transportation network dynamics, road growth model, reliability, vulnerability, fragility, road investment and financing policy

August 28, 2009

Determinants of Route Choice and the Value of Traveler Information: A Field Experiment.

Recently published:

Zhang, Lei and David Levinson (2008) Determinants of Route Choice and the Value of Traveler Information: A Field Experiment. Transportation Research Record: Journal of the Transportation Research Board 2086:81-92 [doi]

A major strategy of federal ITS initiatives and state departments of transportation is to provide traveler information to motorists through various means, including variable message signs, the internet, telephone services like 511, in-vehicle guidance systems, and TV and radio reports. This is relatively uncontroversial, but its effectiveness is unknown. Drivers receive value from traveler information in several ways, including the ability to save time, but perhaps more importantly, other personal, social, safety, or psychological impacts from certainty. This information can be economically valued. The benefits of reduction in driver uncertainty when information is provided at the beginning of the trip by various means is the main variable we aim to measure in this research, in which we assess user preferences for routes as a function of the presence and accuracy of information, while controlling for other trip and route attributes, such as trip purpose, travel time, distance, number of stops, delay, esthetics, level of commercial development, and individual characteristics. Data is collected in a field experiment in which more than 100 drivers, given real-time travel time information with varying degrees of accuracy, drove four of five alternative routes between a pre-selected OD pair in the Twin Cities metro area. Ordinary regression, multinomial, and rank-ordered logit models produce estimates of the value of information with some variation. In general, results show that travelers are willing to pay up to $1 per trip for pre-trip travel time information. The value of information is higher for commute and event trips and when congestion on the usual route is heavier. The accuracy of the traveler information is also a crucial factor. In fact, there do not seem be incentives for travelers to use traveler information at all unless they perceive it to be accurate. Finally, most travelers (70%) prefer that such information should be provided for free by the public sector, while some (19%) believe that it is better for the private sector to provide such service at a charge. Over 35% of subjects are willing to pay for OD-customized pre-trip travel time information.

Keywords: Value of Information, Advanced Traveler Information System (ATIS), Real-Time Traffic Operations, Travel Behavior, Spatial behavior, Wayfinding Behavior, Route Choice.

August 27, 2009

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.

August 26, 2009

New UK high-speed rail plan unveiled

From the BBC New UK high-speed rail plan unveiled

The line would serve Birmingham and Manchester, getting passengers from Glasgow to London in just two hours and 16 minutes, the rail firm said. It rejected several alternative routes, including the east of England.

Judging from the map (linked below), the architecture of the line is clearly to feed London, all of the ancillary cities are as if on a tree with the xylem and phloem oriented to London, it would not be terribly good for say Manchester to Edinburgh or Manchester to Birmingham.

"The firm said that the line would account for 43.7 million journeys per year by 2030, which would result in 3.8 million fewer vehicle journeys and fewer carbon dioxide emissions.".
In other words, more 90% of the trips are switching from rail or air to HSR. Providing better rail service to existing rail passengers is a good thing, but CO2 is hardly a rationale (as more CO2 has to be used going faster than going slower if the electricity is from the same place ... diesel to electric conversion is a separate matter).

Finally, the cost is esimated at $55B for 1500 miles of rail (presumably including triple or quadruple tracking in some sections. Planning will take 5 more years. It is hoped by the promoters the first section (London to Birmingham) will open in 2020. Speeds will max at 200 mph.


rail plan

Birmingham: 45mins, down from 1h 22mins

Liverpool: 1hr 23mins, down from 2hrs 8mins

Manchester: 1hr 6mins, down from 2hrs 7mins

Edinburgh: 2hrs 9mins, down from 4hrs 23mins

Glasgow: 2hrs 16mins, down from 4hrs 10 mins


Also see: London to Glasgow in five minutes, a video showing the West Coast Main Line (which this proposal seems to duplicate) and was recently modernized for 9 billion pounds.

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 www.instr.org 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 http://www.instr.org

David Levinson
RP Braun/CTS Chair in Transportation
University of Minnesota
dlevinson@umn.edu


Sara Van Essendelft
Conference Coordinator
University of Minnesota
612-624-3708
cceconf5@umn.edu

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

May 27, 2009

How volatility begets stability

The human body evolved over time through natural selection. Until very recent advances in medicine which have yet to affect evolution, the entire body depends on various components (heart, lung, brains, etc.), and if any one of them fails, the whole fails. Thus it made no sense to evolve a brain that would noticeably outlast the heart, or a heart that would outlast the lungs. Any effort in a longer-lived brain would be moot as the heart would fail first, and similarly, any attempt to have a heart that would beat longer than the lungs could breathe would be over-engineering. The marginal rate of return of extending the life of any critical organ would probably be equalized in such a scenario.

A similar logic has been alleged to apply to autos, with planned obsolescence. Why design a frame that outlasts the engine? The ideal, from a narrow efficiency point of view, is for all parts to fail simultaneously with no point in spending money on repairs, and no excess wasted at the outset by having parts last longer than the whole.

Both the human body and technological artifacts like automobiles are finite systems. While the date of reckoning for bodies or cars may not be known in advance, nobody naturally lives past about 120 and intensively used cars do not economically (or typically) last past 20 years.

But there are other systems that are potentially infinite. These include cities and networks. While a city or network may not last forever, its potential lifespan is quite uncertain (we may assume that if the sun dies out and planet earth is abandoned, cities will be too, but the 5,000,000,000 year upper limit is beyond comprehension). These potentially infinite systems last significantly longer than their component artifacts. Just as Heraclitus said 'no one ever steps into the same river twice', one never steps into the same city twice, it is continuously evolving, as parts are abandoned, destroyed, replaced, or rebuilt. Quite often, the city while changing its buildings, maintains its networks, whose topographical (and topological) structure outlasts its buildings, in part due to property ownership regulations. (The example of London being rebuilt using essentially the same routes after the 1666 fire being the most illustrative of this case).

I argue the reason that cities (and their networks) last longer is that their components fail at different rates. If all of the components (buildings, plexus (networks, social structures)) failed at the same time (e.g. a fire plus a breakdown of the legal system ensuring property rights), then the site could be abandoned. But as long as most components last, a few failing will not destroy the city. The resources from the remaining components can help rebuild the failed ones. Similarly, networks do not fail together, and the failure of one link (given some redundancy) will not cause the network to collapse.

This volatility in failure rates of components leads to a more stable whole. The price is that only piecemeal, rather than systematic overhaul of the system is permitted.


September 8, 2008

Cloudonomics and Zipcars

An interesting post on "cloudonomics" The 10 Laws of Cloudonomics - GigaOM Many of the ideas are familiar to those who study transportation systems.

As noted previously, I have been thinking about "cloud commuting", we should consider what already is a "cloud" in transportation, and that is the network. The network is provided not by individual travelers, but by agencies that serve many travelers. (This includes both physical infrastructure networks (road, track, port) and carrier (bus, train, plane) networks).

The question is then whether you can drive the economics to the point where the individual no longer needs a vehicle, but that too is provided by the cloud, is available on-demand, ubiquitously, and reliably, at a lower average cost.

As I now let my subscription to zipcar lapse (it seems I cannot just do that, "Please contact us within three business days or your account will be closed and turned over to a collection agency for payment. " ... which seems very rude, I am just not a member this year, no need to get a collection agency involved, I didn't sign up for life, hence why I didn't tell you my new credit card number) I think the economics of this are just not there yet.

Further on the zipcar issue:

"billing problems

Oops! On Aug 18th, we tried to charge the balance of your Aug 18th to Sep 17th invoice ($30.00) to your credit card MasterCard ending XXXX. We were unable to charge the card, possibly because of insufficient funds.

We would like to either try charging your card again or allow you to change your credit card information.

_ I would like to change the credit card number or expiration date on file.

_ The above credit card is working fine. Please try to bill the current invoice balance ($30.00, see your bill) to my credit card right now."

There is no option to cancel. Who do they think they are, the phone company? These are not friendly people despite their moral righteousness.

How the 'Net Works

Nice discussion of the economics and process by which internet traffic is exchanged between carriers:

How the 'Net works: an introduction to peering and transit:

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

May 11, 2008

All Streets

Via Andrew Sullivan, an amazing map of the United States just showing roads and nothing else: all streets | ben fry

All of the major metropolitan areas and geographic features show up as a result.


March 13, 2008

Internet capacity utilization: road hogs and traffic jams

From the NY Times: Video Road Hogs Stir Fear of Internet Traffic Jam

There are some nice quotes by my colleague and co-author Andrew Odlyzko. Internet traffic growth is estimated at 50% a year, which is still very large, but one suspects that percentage growth will continue to slow as saturation is reached for various internet markets. We continue to march up an S-shaped curve, exponential growth does not continue forever. The ability to use cable or wireless bandwidth more efficiently, and to expand capacity is huge, even assuming no major technological advances. One wishes transportation networks had similar flexibility.

The other point to be noted is the continuing use of transportation metaphors (road hog and traffic jam) to describe the internet. Transportation metaphors provide a way to connect readers with the subject, but we should not go too far down the road of employing metaphors when a direct description of the technology will do.

October 20, 2007

Traveler information from Probes

From the NY Times: Navigating With Feedback From Fellow Drivers . The article describe a GPS device from Dash Navigation in which every car is a probe, that reports information back other drivers in the club. This is an idea (hardly original I suspect) I analyzed in Levinson, D. (2002a) The Economics of Traveler Information from Probes. Public Works Management and Policy 6(4) pp 241-250 (April). The model in the paper implies probe information can be very good for detecting incidents, but will be almost useless for recurring congestion, because the lag in the data will be too long to take advantage of it.

May 5, 2007

Email bankruptcy?

From Stuff:
Under siege, users declare 'email bankruptcy' -
Users overwhelmed by their incoming email (underwhelming in their ability to manage time?) are just dumping their inbox.

It would be nice if we could do that in transportation ... a queue forming at an intersection, we will just delete all the cars and start again.

April 29, 2007

MacArthur Maze Meltdown

From today's SFGate - Tanker fire destroys part of MacArthur Maze / 2 freeways closed near Bay Bridge

Ouch.

The agencies involved already seem to be following the rapid reconstruction plan post-Northridge rather than the decade long (1989-1997) reconstruction post-Loma Prieta.

Updates at Nwzchik.

April 5, 2007

Mass Transport and Mainframes

A recent post on Jonathan Schwartz's Weblog : The Glamor in Mass Transit (?) basically talks about the efficiencies of scale. Sun computer, which Schwartz leads, has long argued the network is the computer, and has been trying to move intelligence back from the decentralized desktop into the highly centralized information technology control center.

The comparison between mass vs. private transportation and mass vs. private computing is worth noting. Everyone has a mental image of mass transit, though that image varies by individuals, some who see it is valuable, some as something they would not touch. The perception of course is shaped by their individual experiences, preferences, locations, and so on. Mass transit is efficient in certain specific contexts, but it requires users give up an element of freedom and (in general) spend more time traveling.

The personal computer revolution of the late 1970s and early 1980s enabled individuals to have control over their computing environment, without relying on a third party to provide that service. This provided freedom (I can write my own programs, and run them when I want in real-time, not having to go down to the computer center and load my program on to the Cyber at Rich Hall at Georgia Tech, and wait 20 minutes for the output to be printed (in below zero F temperatures, really, in Atlanta, January 1985, you can look it up .. Reagan's second innaugural was delayed by the same coldfront) so that I can do a homework problem for Professor Betamax's Fortran class (the course was videotaped, and was replayed every hour, so we could attend when we wanted). I hear horror stories of people who work in controlled environments like Lotus Notes, where they can't deal with email conveniently but require using a browser with a sluggish email program behind it.

So as much as we might curse personal computers, or cars, freedom of action is what they provide.

A good mass transit system, like the so-called web 2.0, can provide the same freedom through its ubiquity, and free the user from the need to manage complex systems (automobiles, computers), focusing only on the higher level decision (what I want to do, what I want to say, where I want to go). But it builds in additional dependencies (will the internet be up? will I have to pay to get access in a hotel room to my data? will the bus show up on time? does the bus really go there? what will google do with my data? do I want to see personalized ads based on my research paper on transportation?).

Freedom from and Freedom to are important distinctions. I would much rather have Freedom to act than freedom from cost or risk of acting.

What should be owned and what should be rented or provided as a service is one of those essentially tug-of-wars that shape every aspect of the modern economy. There must be some economies of scale, or we would not see scale, but there must also be diseconomies, and loss of freedom is one of them.

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.

September 5, 2006

Access to Destinations Report Released

Our first report in the Access to Destinations Series: Development of Accessibility Measures
has finally been released.

The most interesting finding (which still awaits corroboration) is that despite the rising congestion of the past decade, accessibility in the Twin Cities region (measured as the number of things (jobs, workers, etc.) that you can get to in a fixed period of time) has been improving. Clearly this would be because there are more things per unit time, not because you can cover more distance per unit time. Increasing density increases accessibility, this is why cities form in the first place, it is nice to see it in the data. More in the final report. Thanks to my colleague Ahmed El-Geneidy who did most of the number crunching.

Continue reading "Access to Destinations Report Released" »

August 24, 2006

Article on wayfinding

A nice blog post comparing maps vs. landmarks as wayfinding techniques, Cognitive Daily: Different ways of finding your way, based on the published article:
Fields, A.W., & Shelton, A.L. (2006). Individual skill differences and large-scale environmental learning. Journal of Experimental Psychology: Learning, Memory, and Cognition, 32(3), 506-515.

Apparently maps are superior to landmarks for learning (according to this experiment).

Having been in Japan last week, it would be nice if all the maps actually were oriented the same way, (i.e. North is up), rather than the apparently random orientation they seem to have.