June 2010 Archives
Chan, Weichenberg, and Medard Optical Flow Switching. A proposed communications protocol, but one which has some insights for transportation (if not immediate applicability)
Motivated by the minimization of network management and switch complexity in the network core, flows are serviced as indivisible entities. That is, data cells comprising a flow traverse the network contiguously in time, along the same wavelength channel, and along the same spatial network path. This is in contrast to packet switched networks, where transactions are broken up into constituent cells, and these cells are switched and routed through the network independently. Note that in OFS networks, unlike packet switched networks, all queuing of data occurs at the end users, thereby obviating the need for buffering in the network core. Core nodes are thus equipped with bufferless optical cross-connects (OXCs). OFS is a centralized transport architecture in that coordination is required for logical topology reconfiguration. However, OFS traffic in the core will likely be efficiently aggregated and sufficiently intense to warrant a quasi-static logical topology that changes on coarse time scales. Hence, the centralized management and control required for OFS is not expected to be onerous. The network management and control carried out on finer time-scales will be distributed in nature in that only the relevant ingress and egress access networks will need to communicate.(emphasis added)
So instead of storing and buffering (on-road queueing), they allocate the whole path between origin and destination to the flow (a trip).
Of course, since this is communications, there are some things they can do that transportation cannot:
If any errors are detected, a request for retransmission of the whole file is done via feedback to the transmitter.
(Sorry, your trip didn't work out, please have your clone repeat the trip).
Strib has an article on Jefferson Lines, a local Intercity Bus company: Jefferson Lines: Flying low
Traffic on daily roundtrips has risen from 16 passengers a day between Duluth and Minneapolis when Jefferson took over from Greyhound in 2004 to about 90 a day. And that's before Jefferson added two more express routes last week.
Compare with the proposed so-called High Speed Rail (110mph) Northern Lights Express which will cost at least $615 M (and probably closer to $1B) to build, serving the same market.
The American Bus Association Foundation commissioned a study by DePaul University Prof. Joseph Schwieterman that found that motorcoaches are the most fuel-efficient transportation mode. They provide, on average, 207 passenger miles per gallon, compared with 27 miles per gallon for single-occupant automobiles, 44 miles per gallon for airlines and 92 miles per gallon for commuter railroads, based on typical passenger loads.
What's more, the airlines need something more than 80 percent of seats full to make money. [Jefferson Lines] needs fewer than half the seats filled on a 55-passenger coach to make a profit.
So the NLX will travel 155 miles in 2 hours (averaging 77 MPH), while buses, which are slightly slower (we could say they should be able to average 60 MPH on this route, which is almost entirely interstate), but more fuel efficient. So the difference is 0.58 hours. Is 17 MPH for 2 hours (i.e. 34 minutes savings for 90 people a day worth a $1B capital investment and a higher environmental cost? 90 people * 34 minutes/person * 365 days/year * 30 years = 33 507 000 person minutes saved. (or $30/minute or $1800/hour). That is a high value of time required to justify this HSR line over its most similar alternative, commuter bus. (I.e. car is not the right comparison, since most people are going point to point, not station to station, and will need transportation on the other end. People going to/from Duluth to the MSP airport to change planes, will probably still want to fly rather than transfer in downtown Minneapolis at significantly extra time)
(This back of the envelope analysis ignores discounting (which makes the value of time higher) and induced demand (which makes the value of time smaller))
OK, so bus is not marketed the way HSR would be, and HSR might attract more passengers. But surely this problem is solvable for significantly less cost than the capital required to construct a new HSR line.
Nice Ride Minnesota launched recently, it is a bike sharing program for Minneapolis. Some photos of one of their campus, and their Dinkytown site are below. They seem to have more bikes than Zipcar has cars, which befits our position as one of the best cities for biking. I even saw someone using it. The user interface looks quite good, if we could only get this level of investment for buses.
From the Howard County, Maryland blog Tales Of Two Cities: Love Thy Neighbor
An almost perfect example of how to respond to pure free-riding problems, establish exclusion. Phase 1 paid for a road through their neighborhood which connects to a future Phase 2 development. Phase 2 comes along, and cannot come to terms with Phase 1 about paying for this local road (owned by a homeowners association, apparently, and thus is fenced out.
A few weeks ago I received an email from a Tales of Two Cities reader about a turf war going on between the residents of the Legacy at Ellicott Mills Phase 1 and Phase 2. The conflict between the two active adult communities has escalated to the point where the Phase 1 residents have now gated off their community from Phase 2, denying Phase 2 residents direct access to Route 104.
There is a fair solution to this problem.
A typical remote control for Cable TV in the first part of the 21st century has up and down arrows to adjust channels. Pushing the up (plus) button will move you away from channel 0, while the down button will move you toward channel 0 (although if you reach the final channel, you will return to home). But remote controls also have a navigation for the onscreen guide. this has an up, down, left, and right arrow. The up arrow moves you through the onscreen guide, but here up move you toward channel 0, while down moves you away from 0. The left and right arrows move you forward or backward through time.
These remote controls have a further set of controls to operate an auxiliary device like a DVD or an inbuilt device like a personal video recorder. The left arrow, following the convention from tape recorders, plays (forward in time), while the double left arrow (on the right-most side) is fast forward and the double right-pointing arrow (on the left side) moves you in reverse (rewind). Other buttons do other things.
Complaints about the complexity of modern remote controls are hardly unique (Nielson, J. (2004), 'Remote Control Anarchy'.) . Each remote is custom for a particular box, so as people accumulate boxes attached to TVs, the number of remotes increases accordingly. The utopia of the universal remote remains unreached; one hopes the situation will not sustain for another few decades before standardization moves in, or some other interface becomes widespread.
Like remote controls, keypads are another area where conventions may confuse.
Keypads on telephones and calculators represent the same ten digits, however they have different layouts. The telephone keypad, introduced with the advent of Touch Tone dialing by the Bell System in the 1960s places the number '0' (or letter 'O' for operator, it is not always clear on telephones) at the bottom, and then numbers digits 1 - 9 in three rows of three columns each from the top. A calculator keypad (also used on computer keyboards) on the other hand, while it places 0 at the bottom, numbers 1 to 9 also in three rows of three columns, but in this case beginning at the bottom, as shown in the Figure. These conventions have carried over to computers, which could array numbers in any random way, but use the different conventions to represent the different devices. Newer devices, such as television remote controls, could use either, but typically follow the telephone layout (though some have original layouts themselves, e.g. going from 1 to 4 on the first row, 5 to 8 on the second row, and 9 and 0 on the third row).
For operating a television, rarely an urgent activity, the additional cognitive load of a poorly-designed or non-standard interface is annoying, but not dangerous. With the case of election ballots, such confusion and resulting error may change the outcomes (such as the odd butterfly ballot used in West Palm Beach, Florida in the 2000 Presidential election, resulting in a disproportionate (compared to other jurisdictions) number of votes for Pat Buchanan, and likely giving the state of Florida, and thus the United States electoral college and the presidency to George W. Bush).
American travelers trying to write emails in some European countries may note that the standard QWERTY keyboard found in the English speaking world (so-named for the keys on the top-row of letters) has been replaced by a keyboard, which mainly swaps the Y and Z, but has some minor changes, dubbed the QWERTZ kezboard. This is just enough to throw off touch-tzpists (er, typists). I am sure the confusion is two-way.
For driving cars in the United States, many functions have been fortunately standardized. The brake foot pedal is on the left, the accelerator on the right. The steering wheel itself usually performs as expected. Less critical functions remain confusing, especially when switching cars, or driving an unfamiliar vehicle, such as a rental car, the difficulty compounds as this is usually done in an unfamiliar place. Where is the windshield wiper? The light switch? The brights? The transmission control? The radio? The environmental controls? The locks? The window controls? The rear-view window control? The unlock for the trunk? The unlock for the gas tank? Where is the gas tank - driver or passenger side? All vary with make, model, and year of vehicle.
Driving on the left of the right is standardized locally, but not globally. As any traveler from continental Europe, North America, or South America knows, things differ on the islands of Great Britain, New Zealand, Japan, the Caribbean, and even the island-continent of Australia.
Traffic signals usually report red on top and green on bottom. What does it mean when the light is simultaneously red and green? Or red and yellow (amber), or green and yellow? Or the green light flashes? All of these patterns are local, but not global standards.
Standards are pervasive (imagine if each car required a different gas nozzle at a gas station (beyond the obvious differentiation for leaded and unleaded). But what in the world could be standardized and produce coordination externalities, but just has not been because the institutions for such organization have not yet been established?
John Graham-Cumming: The Elevator Button Problem
User interface design is hard. It's hard because people perceive apparently simple things very differently. For example, take a look at this interface to an elevator:
Now imagine the following situation. You are on the third floor of this building and you wish to go to the tenth. The elevator is on the fifth floor and there's an indicator that tells you where it is. Which button do you press?
Most people probably say: "press up" since they want to go up. Not long ago I watched someone do the opposite and questioned them about their behavior. They said: "well the elevator is on the fifth floor and I am on the third, so I want it to come down to me".
Too cool for words: Live map of London Underground trains
There should be an LED of this at every station. (And similarly for buses at busstops).
Article in Guardian on said thing The live Underground train map: what else can be built with transport data?
From Autoblog Uni-signal Traffic light with shapes for the color blind.
The principle seems right, the symbols seem wrong. Red should be an octagon, to align with the stop sign. If we use LEDs we could actually spell out the word "stop" (though this might have trouble in winter). An idea worth playing with.
Forwarded by my favorite Mefite Commuting-When is it worth it? | Ask MetaFilter, an interesting thread on when is commuting 1 hour (each way) worth it.
In Silicon Valley / San Jose Business Journal Video conferencing could save $19B a year
A study sponsored by AT&T Inc. and conducted by the Carbon Disclosure Project estimates that skipping business trips and using video conferencing instead could save $19 billion a year.
The study also said that by 2020 companies in the US and UK that have more than $1 billion in revenue could cut CO2 emissions equal to taking about 1 million vehicles off the road for a year.
If the government confiscated that, it would *almost* be enough to pay for a small US high-speed rail system. However, if business travelers teleconferenced, we might not need intercity HSR. Clearly teleconferencing is getting better. (Although institutions are lagging individuals, I regularly video-conference with my mom, and managed my students from the UK in 2006-07 successfully, I cannot get any number of bureaucratic institutions to get this working without cajoling). Any opportunity to avoid the hassle and headache of most business travel would be greatly appreciated. As Wayne Gretzky said "Skate to where the puck is going to be, not where it has been."
full study here: Telepresence Revolution (the model looks fairly simple, but the general point obtains under any number of reasonable assumptions).
Streetsblog New York City reports on the recent HSR conference Low Expectations for High-Speed Rail at NYU Conference
My talk on Economic Development and High Speed Rail gets a prominent mention:
"The most controversial comments of the day came from Professor David Levinson, a transportation engineer at the University of Minnesota. Pointing to pictures of surface parking lots next to high-speed rail stations in Japan and Europe, he argued that "there is no advantage to adjacency" -- that high-speed rail stations are barely more likely to spur walkable development than airports.
He also walked through a body of research showing that high-speed rail gives a significant economic boost to whichever city serves as the system's hub, but does little for cities on the spokes. Showing maps of hub-and-spoke networks proposed by municipalities from around the country, he noted that every city, no matter how small, imagined itself at the center."
This is not quite what I said, or at least, not quite what I thought I said, but it's not too far off. I meant, the economic boost for the hub is weak, the economic boost for the spokes is approximately non-existant.
A Keynote version of the slides are available here.
The paper is here.
With the rise of RSS feeds, it is easier to stay on top of the academic literature, especially for those of us without a nearby physical library. I have compiled a list of the journals I track into an OPML file, which should be importable into the newsreader of your choice (e.g. Google Reader)
Also, the list of transportation blogs that I follow is below:
Journal of Transport and Land Use, Volume 3 Issue 1 is now out.
- The impact of telecommuting on residential relocation and residential preferences: A latent class modelling approach by Dick Ettema
- Equip the warrior instead of manning the equipment: Land use and transport planning support in the Netherlands by Marco te Brommelstroet
- Finding food: Issues and challenges in using Geographic Information Systems (GIS) to measure food access by Ann Forsyth, Leslie Lytle, and David Van Riper
- Efficiency and equity of orbital motorways in Madrid by Juan Carlos Martin, Juan Carlos García-Palomares, Javier Gutierrez, and Concepción Román
- Evaluation of land use-transportation systems with the Analytic Network Process by Reza Banai
- Assessing the impacts of Light Rail Transit on urban land in Manila by Javier F. Pacheco-Raguz
- Discussion of "The Role of Employment Subcenters in Residential Location Decisions" between Uri Avin and Daniel A. Rodriguez
From Gizmodo Is This the Craziest Bridge Ever Designed?
How to change from driving on the left to driving on the right:
I don't know if the "Pearl River Necklace bridge is the craziest bridge ever designed, but it sure looks like the most twisted one. It's a clever solution to a very real and obvious problem, however.
The bridge is part of a proposal by NL Architects to connect Hong Kong with mainland China. To do that, they had to solve a problem: In Hong Kong, people drive on the left side of the road. In mainland China, they drive on the right side. Here's the solution: A road flipper that physically twists the roads over each other.
I hope the project goes forward, because I've always wanted to drive in a gigantic Scalextric. [Design Boom]"
I will be at High Speed Rail: Leveraging Federal Investment Locally at NYU on Wednesday:
HIGH SPEED RAIL: LEVERAGING FEDERAL INVESTMENT LOCALLY
The Rudin Center for Transportation Policy and Management is pleased to announce High Speed Rail: Leveraging Federal Investment Locally, a symposium to be held on June 16th, 2010.
Following the January 2010 rail funding announcement by the U.S. Department of Transportation, interest in rail investment - and what it means for American communities - has continued to expand. Conversations are taking place across the country, bringing in new participants as well as experienced professionals from around the world to discuss the new corridors. In focusing on how to implement new rail corridors there is a risk of overlooking the need to manage the regional impacts of the nodes that comprise these systems. Leveraging Federal Investment Locally will enhance the national dialogue on high-speed rail investment through a focus on how new facilities will be linked to existing regional transportation infrastructure and economic development efforts. In addition, there will be an examination of the political context of establishing new rail infrastructure in a democratic nation where land use is controlled locally.
Polly Trottenberg, Assistant Secretary for Transportation Policy at the U.S. Department of Transportation
David Levinson, University of Minnesota
Anthony Perl, Simon Fraser University
Frank Zshoche, Managing Director, Civity Management Consultants, Hamburg Germany
The event is co-sponsored by Parsons Brinckerhoff and presented in Partnership with the American Public Transportation Association (APTA).
When: 6/16/2010 8:30am-2:00pm
The Kimmel Center, Rosenthal Pavilion
60 Washington Square South, New York, NY 10012 map
Design Observer discusses All Those Numbers: Logistics, Territory and Walmart describing Wal-Mart's spread across the US, and the underlying logistics driving it. The total footprint of Wal-Mart's US stores is larger than Manhattan.
Recent working paper:
- Levinson, David and Bernadette Marion (2009)
The City is Flatter: Changing Patterns of Job and Labor Access in Minneapolis-Saint Paul, 1995-2005
This study describes the measurement of accessibility by automobile for the Minneapolis - Saint Paul (Twin Cities) region over the period from 1995 to 2005. In contrast to previous analyses of accessibility, this study uses travel time estimates derived, to the extent possible, from actual observations of network performance by time of day. A set of cumulative opportunity measures are computed with transportation analysis zones (TAZs) as the unit of analysis for 1995 and 2005. Analysis of the changes in accessibility by location over the period of study reveals that, for the majority of locations in the region, accessibility increased over this period, though the increases were not uniform. A "flattening" or convergence of levels of accessibility across locations was observed over time, with faster-growing suburban locations gaining the most in terms of employment accessibility. An effort to decompose the causes of changes in accessibility into components related to transportation network structure and land use (opportunity location) reveal that both causes make a contribution to increasing accessibility, though the effects of changes to the transportation network tend to be more location-specific. Overall, the results of the study demonstrate the feasibility and relevance of using accessibility as a key performance measure to describe the regional transportation system.
Eric Raymond posits The Iron Laws of Network Cost Scaling (which he applies strictly to communications networks).
1. Upgrade cost per increment of capacity decreases as capacity rises.
2. Network costs scale primarily with the number of troubleshooters required to run them, not with capacity.
3. Under market pressure, network pricing evolves from metered to flat-rate.
I am not sure I buy these as laws, though I don't necessarily disagree with as general observations,
1. is economies of scale of capital costs, which I think do operate in telecommunications in a way differently than transportation
2. is operations and maintenance, which is a function of demand as much as supply. Again telecom differs from transportation
3. assumes we are on a downward sloping average cost curve. Transportation professionals are trying to move pricing in the other direction (to date, largely unsuccessfully), especially in congested areas, where costs slope upwards.
Linked to in comments in an article in Slashdot: "Traffic-Flow Algorithm can reduce fuel consumption
Recent working paper (extending recent blog posts):
- Levinson, David, (2010), Economic Development Impacts of High Speed Rail, No 000072, Working Papers, University of Minnesota: Nexus Research Group.
This paper reviews the state of high-speed rail (HSR) planning in the United States c. 2010. The plans generally call for a set of barely inter-connected hub-and-spoke networks. The evidence from US transit systems shows that lines have two major impacts. There are positive accessibility benefits near stations, but there are negative nuisance effects along the lines themselves. High speed lines are unlikely to have local accessibility benefits separate from connecting local transit lines because there is little advantage for most people or businesses to locate near a line used infrequently (unlike public transit). However they may have more widespread metropolitan level effects. They will retain, and perhaps worse, have much higher, nuisance effects. If high-speed rail lines can create larger effective regions, that might affect the distribution of who wins and loses from such infrastructure. The magnitude of agglomeration economies is uncertain (and certainly location-specific), but presents the best case that can be made in favor of HSR in the US.
Recent working paper:
- Carlos, Carrion-Madera, and Levinson, David, (2010), Value of Reliability: High Occupancy Toll Lanes, General Purpose Lanes, and Arterials, No 000073, Working Papers, University of Minnesota: Nexus Research Group.
In the Minneapolis-St. Paul region (Twin Cities), the Minnesota Department of Transportation (MnDOT) converted the Interstate 394 High Occupancy Vehicle (HOV) lanes to High Occupancy Toll (HOT) lanes (or MnPASS Express Lanes). These lanes allow single occupancy vehicles (SOV) to access the HOV lanes by paying a fee. This fee is adjusted according to a dynamic pricing system that varies with the current demand. This paper estimates the value placed by the travelers on the HOT lanes because of improvements in travel time reliability. This value depends on how the travelers regard a route with predictable travel times (or small travel time variability) in comparison to another with unpredictable travel times (or high travel time variability). For this purpose, commuters are recruited and equipped with Global Positioning System (GPS) devices and instructed to commute for two weeks on each of three plausible alternatives between their home in the western suburbs of Minneapolis eastbound to work in downtown or the University of Minnesota: I-394 HOT lanes, I-394 General Purpose lanes (untolled), and signalized arterials close to the I-394 corridor. They are then given the opportunity to travel on their preferred route after experiencing each alternative. This revealed preference data is then analyzed using mixed logit route choice models. Three measures of reliability are explored and incorporated in the estimation of the models: standard deviation (a classical measure in the research literature); shortened right range (typically found in departure time choice models); and interquartile range (75th - 25th percentile). Each of these measures represents distinct ways about how travelers deal with different sections of reliability. In all the models, it was found that reliability was valued highly (and statistically significantly), but differently according to how it was defined. The estimated value of reliability in each of the models indicates that commuters are willing to pay a fee for a reliable route depending on how they value their reliability savings.
Recent working paper:
- Jenelius, Erik, Mattsson, Lars-Goran and Levinson, David, (2010), The traveler costs of unplanned transport network disruptions: An activity-based modeling approach, No 000074, Working Papers, University of Minnesota: Nexus Research Group.
In this paper we introduce an activity-based modeling approach for evaluating the traveler costs of transport network disruptions. The model handles several important aspects of such events: increases in travel time may be very long in relation to the normal day-to-day fluctuations; the impact of delay may depend on the flexibility to reschedule activities; lack of information and uncertainty about travel conditions may lead to under- or over-adjustment of the daily schedule in response to the delay; delays on more than one trip may restrict the gain from rescheduling activities. We derive properties such as the value of time and schedule costs analytically. Numerical calculations show that the average cost per hour delay increases with the delay duration, so that every additional minute of delay comes with a higher cost. The cost varies depending on adjustment behavior (less adjustment, loosely speaking, giving higher cost) and scheduling flexibility (greater flexibility giving lower cost). The results indicate that existing evaluations of real network disruptions have underestimated the societal costs of the events.
Review of Transit Apps in NY Times Phone Smart - With Transit Map Apps, No Refolding Required
Among those interviewed:
Brendan Nee, one of AnyStop's developers, said the app was best suited to those who already knew their routes, and wanted to optimize the timing of their journeys. In that respect, longer-term visitors and commuters will find it more useful than tourists.
Brendan is one of my former students before defecting to the People's Republic of Berkeley. We wrote the working paper:
Nee, Brendan and David Levinson (2004) Value of Information for Transit Riders. back before there was real-time mobile information of any usefulness.
Brendan also orchestrated the data collection for the study that became 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.
So exposure to academic research can lead to marketable products.
Recent working paper
- Huang, Arthur and Levinson, David, (2010), Modeling the Minneapolis Skyway Network, No 000075, Working Papers, University of Minnesota: Nexus Research Group.
Adopting an agent-based approach, this paper explores the topological evolution of the Minneapolis Skyway System from a microscopic perspective. Under a decentralized decision-making mechanism, skyway segments are built by self-interested building owners. We measure the accessibility for the blocks from 1962 to 2002 using the size of office space in each block as an indicator of business opportunities. By building skyway segments, building owners desire to increase their buildings' value of accessibility, and thus potential business revenue. The skyway network in equilibrium generated from the agent model displays similarity to the actual skyway system. The network topology is evaluated by multiple centrality measures (e.g., degree centrality, closeness centrality, and betweenness centrality) and a measure of road contiguity, roadness. Sensitivity tests such parameters as distance decay parameter and construction cost per unit length of segments are performed. Our results disclose that the accessibility- based agent model can provide unique insights for the dynamics of the skyway network growth.
Tom Vanderbilt links to an article in Ad Age about the decline in drivers licenses among youth between 1978 and 2008 in the US. This data surprises me, not just the decline in youth licenses, which can be explained as Tom notes by graduated driver's licensing programs, but a decline between 1998 and 2008 for all drivers by age group, which is shown at the bottom of the Ad Age article according to USDOT. While I know auto ownership peaked in the past few years (with a decline in total cars last year), and the recession and high gas prices have changed patterns in the past half decade, this is remarkable if true.
I retain some skepticism about whether this is instead explained by a switch to other forms of IDs among non-drivers, (i.e. in the past a DL was considered standard ID, so people got that from the DMV even if they did not drive) or some sort of other accounting issue.
Recent working paper:
- Chi, Guangqing, Zhou, Xuan, McClure, Timothy, Gilbert, Paul, Cosby, Arthur, Zhang, Li, Robertson, Angela and Levinson, David, (2010), Gasoline Prices and Their Relationship to Drunk-Driving Crashes, No 000076, Working Papers, University of Minnesota: Nexus Research Group.
This study investigates the relationship between changing gasoline prices and drunk-driving crashes. Specifically, we examine the effects of gasoline prices on drunk-driving crashes in Mississippi by age, gender, and race from 2004-2008, a period experiencing great fluctuation in gasoline prices. An exploratory visualization by graphs shows that higher gasoline prices are generally associated with fewer drunk-driving crashes. Higher gasoline prices depress drunk- driving crashes among younger and older drivers, among male and female drivers, and among white, black, and Hispanic drivers. The statistical results suggest that higher gasoline prices lead to lower drunk-driving crashes for female and black drivers. However, alcohol consumption is a better predictor of drunk-driving crashes, especially for male, white, and older drivers.