The Pedestrian By Ray Bradbury

The Pedestrian (1953) by science fiction writer Ray Bradbury, on another view of police traffic stops, c. 2053.

“To enter out into that silence that was the city at eight o’clock of a misty evening in November, to put your feet upon that buckling concrete walk, to step over grassy seams and make your way, hands in pockets, through the silences, that was what Mr Leonard Mead most dearly loved to do. He would stand upon the corner of an intersection and peer down long moonlit avenues of sidewalk in four directions, deciding which way to go, but it really made no difference; he was alone in this world of 2053 A.D., or as good as alone, and with a final decision made, a path selected, he would stride off, sending patterns of frosty air before him like the smoke of a cigar.”

It’s a short story, but probably still under copyright in the US, so I will merely link to the copyright violator rather than violate copyright myself. The rest is here.

This is another entry into transport literature, a narrow genre.

Tenure-Track Faculty Position University of Minnesota, Twin Cities

The Department of Civil, Environmental, and Geo- Engineering at the University of Minnesota seeks applications for a tenure-track faculty position in the area of transportation engineering. We are particularly interested in applicants with strong fundamentals that allow them to easily move across disciplinary boundaries and become involved in department, university, and national interdisciplinary research opportunities. The position is expected to be at the rank of assistant professor, although exceptional candidates at all ranks will be considered.

We are seeking individuals with an academic background and research potential in one or more of the following areas: traffic flow theory; traffic control and operations; transportation safety and security; modeling and simulation of transportation systems; intelligent transportation systems. Other areas of transportation engineering also will be considered.

Candidates will be expected to initiate and maintain a vibrant externally-funded research program. Teaching responsibilities will include existing undergraduate and graduate courses, as well as the opportunity to develop new courses in specialty areas. An earned doctorate is required at the time of the appointment.

Applications must be completed online at – Assistant Professor – Associate / Full Professor
Include a letter of intent, a CV with a list of publications, complete contact information for three references, and a statement of teaching and research interests. The review of applications will begin October 31, 2016. Applications will continue to be accepted until the position is filled. Expected appointment is Fall 2017.

The Department of Civil, Environmental, and Geo- Engineering (CEGE) at the University of Minnesota is affiliated with the Center for Transportation Studies, Roadway Safety Institute, and St. Anthony Falls Laboratory, and its faculty are involved with these and other research centers, including the Minnesota Traffic Observatory and the Multi-Axial Subassemblage Testing Laboratory. CEGE is one of twelve departments within the College of Science & Engineering, which offers outstanding opportunities for interdisciplinary research due to the unique combination of mathematics, science, and engineering in one college.

Using Temporal Detrending to Observe the Spatial Correlation of Traffic

Recent working paper: Figure2.jpg

This empirical study sheds light on the correlation of traffic links under different traffic regimes. We mimic the behavior of real traffic by pinpointing the correlation between 140 freeway traffic links in a sub-network of the Minneapolis – St. Paul highway system with a grid-like network topology. This topology enables us to juxtapose positive correlation with negative correlation, which has been overlooked in short-term traffic forecasting models. To accurately and reliably measure the correlation between traffic links, we develop an algorithm that eliminates temporal trends in three dimensions: (1) hourly dimension, (2) weekly dimension, and (3) system dimension for each link. The correlation of traffic links exhibits a stronger negative correlation in rush hours, when congestion affects route choice. Although this correlation occurs mostly in parallel links, it is also observed upstream, where travelers receive information and are able to switch to substitute paths. Irrespective to the time-of-day and day-of-week, a strong positive correlation is witnessed between upstream and downstream links. This correlation is stronger in uncongested regimes, as traffic flow passes through consecutive links more quickly and there is no congestion effect to shift or stall traffic. The extracted correlation structure can augment the accuracy of short-term traffic forecasting models.

Spatiotemporal Traffic Forecasting: Review and Proposed Directions

Recent working paper: Figure3

This paper systematically reviews studies that forecast short-term traffic conditions using spatial dependence between links. We synthesize 130 extracted research papers from two perspectives: (1) methodological framework, and (2) approach for capturing and incorporating spatial information. From the methodology side, spatial information boosts the accuracy of prediction, particularly in congested traffic regimes and for longer horizons. There is a broad and longstanding agreement that non-parametric methods outperform the naive statistical methods such as historical average, real time profile, and exponential smoothing. However, to make an inexorable conclusion regarding the performance of neural network methods against STARIMA family models, more research is needed in this field. From the spatial dependency detection side, we believe that a large gulf exists between the realistic spatial dependence of traffic links on a real network and the studied networks. This systematic review highlights that the field is approaching its maturity, while it is still as crude as it is perplexing. It is perplexing in the conceptual methodology, and it is crude in the capture of spatial information.

Development and Application of the Network Weight Matrix to Predict Traffic Flow for Congested and Uncongested Conditions

Recent working paperFigure1d

  • Ermagun, Alireza, and Levinson, D. (2016) Development and Application of the Network Weight Matrix to Predict Traffic Flow for Congested and Uncongested Conditions (Working Paper).

    To capture a more realistic spatial dependence between traffic links, we introduce two distinct network weight matrices to replace spatial weight matrices used in traffic forecasting methods. The first stands on the notion of betweenness centrality and link vulnerability in traffic networks. To derive this matrix, we assume all traffic flow is assigned to the shortest path, and thereby we used Dijkstra’s algorithm to find the shortest path. The other relies on flow rate change in traffic links. For forming this matrix, we employed user equilibrium assignment and the method of successive averages (MSA) algorithm to solve the network. The components of the network weight matrices are a function not simply of adjacency, but of network topology, network structure, and demand configuration. We tested and compared the network weight matrices in different traffic conditions using Nguyen-Dupuis network. The results led to a clear and unshakable conclusion that spatial weight matrices are unable to capture the realistic spatial dependence between traffic links in a network. Not only do they overlook the competitive nature of traffic links, but they also ignore the role of network topology and demand configuration. In contrast, the flow-weighted betweenness method significantly operates better than unweighted betweenness to measure realistic spatial dependence between traffic links, particularly in congested traffic conditions. The results disclosed that this superiority is more than 2 times in congested flow situations. However, forming this matrix requires considerable computational effort and information. If the network is uncongested the network weight matrix stemming from betweenness centrality is sufficient.

An Introduction to the Network Weight Matrix

Recent working paperFigure1

This study introduces the network weight matrix as a replacement for the spatial weight matrix to measure the spatial dependence between links of a network. This matrix stems from the concept of betweenness centrality and vulnerability in network science. The elements of the matrix are a function not simply of proximity, but of network topology, network structure, and demand configuration. The network weight matrix has distinctive characteristic, which are capable of reflecting spatial dependence between traffic links: (1) The elements are allowed to have negative and positive values, which capture competitive and complementary nature of links, (2) The diagonal elements are not fixed to zero, which takes the self-dependence of a link upon itself into consideration, and (3) The elements not only reflect the spatial dependence based on the network structure, but they acknowledge the demand configuration as well. We verified the network weight matrix by modeling traffic flows in a 3×3 grid test network with 9 nodes and 24 directed links connecting 72 origin-destination (OD) pairs. The results disclose models encompassing the network weight matrix outperform both models without spatial components and models with the spatial weight matrix. This leads inexorably to the conclusion that the network weight matrix represents a more accurate and defensible spatial dependency between traffic links, and thereby augments traffic flow prediction.

Ramp Meters on Trial

This is a recording of a talk I gave at the University of Minnesota back in the early 2000s about Ramp Meters on Trial. Ramp meters were controversial when I first arrived in Minnesota, as the delays on ramps were uncapped, so people might wait 10 or even 20 minutes before being allowed onto the freeway. This led to a ramp meter shutdown in 2000, which was a great “natural” experiment. [Link]

Our research on the topic includes:


The best Anime about resistance to Japanese New Town planning featuring magical raccoons that you have probably never seen


Tama New Town is a planned suburb of Tokyo with about 200,000 people. It is the setting of the gorgeous Studio Ghibli film Whisper of the Heart, (really, all the Ghibli films are worth seeing). More to the point, its construction, and the destruction of the natural and earlier agricultural environment, are the centerpiece of the 1994 Ghibli film Pom Poko.

The movie features raccoon dogs whose homes are being disturbed by rapacious development (of Tama), and their attempts to foment resistance, both through aggressive tactics as well use of magic to convince the humans the area is haunted. Nevertheless construction proceeds. Other stunts are also attempted. The movie provides insight into late 20th century Japanese culture, and like many Ghibli films has detailed animation of the real world. You don’t learn too much about planning, but it still belongs in the short list of planning-cinema, along with the 1992 movie  Singles of the same era.

Discussing the Driverless Future

Hillary Reeves of Transit for Livable Communities summarized our Transportation on Tap panel: Discussing the Driverless Future:

At our latest Transportation on Tap happy hour event in Minneapolis, a fabulous panel of speakers and a lively crowd discussed what changes are coming with driverless vehicles. The biggest take-away? Whatever you call them, autonomous vehicles (AV) are coming fast and our regional planning isn’t keeping up. As John Levin, who heads up Strategic Initiatives at Metro Transit, reminded everyone, five to six years ago we did not have bike-sharing, Lyft, Uber, or car2go, nor the many apps that are facilitating the sharing economy.

“A major technological shift is coming and the question is how to respond to it. Policy makers have to focus on making it affordable and on accessibility,” said Leili Fatehi, a legal scholar and deputy director of Self-Driving Minnesota. John Levin called for making decisions based on core values and principles such as mobility and access.

Fatehi said, “There is a fundamental equity question about service delivery model for AV and how we deliver transit.” Earlier this year, Fatehi testified at the Minnesota legislature in support of a proposed law—H. F. 3325 TIM’s (Transportation Independence for Many) Bill—that would establish a taskforce and demonstration project to advance self-driving car technology to meet the transportation needs of people with disabilities.

“Planning should be done more frequently and more dynamically,” said David Levinson of the U of M’s Accessibility Observatory. But across the nation, few comprehensive plans are factoring in driverless vehicles, he said. Fatehi, who has worked with other emerging technologies, urged planners to adopt the principles of “anticipatory governance” and focus on flexible technology investments.

Here’s a snippet of the discussion at Transportation on Tap:

  1. Will AVs supplant transit?

John Levin: “With high capacity transit, such as LRT, it’s difficult to imagine putting all those folks (transit riders) into individual vehicles, even with the better allocation of vehicle space that would come with AV. The issue is not supplanting high capacity vehicles but using AVs to feed people in.”

Levin said AVs also could help seniors age in place and provide mobility in places harder to serve with transit, such as in suburban areas with dispersed development patterns.

  1. Will only the rich get to have these cars?

David Levinson: They will be for wealthy people first. But with mass production the cost will go down. This technology won’t behave quite like Moore’s Law (doubling every two years, as with transistors and circuits) but especially with battery development, it will start doubling every 10 years, with ever more efficient and smaller charging systems. Imagine, for example, charging platforms built into the pavement of bus stops, so that the electric bus wirelessly recharges when it stops to pick up passengers. Over time, sensors will replace steering wheels and brakes. These vehicles will be less expensive to design and insure.

  1. Do you see changes in the ways that we design roads?

David Levinson: For first generation AV, we’ll need good paint on roads. Snow cover also poses challenges for AV. Over longer time, there will be no lanes, no signs, no traffic control at all.

Q—I am representing older generation. Someday they will take my keys. Will self-driving cars be the answer?

David Levinson: Yes, for seniors, persons with disabilities, even kids ages 5-16. These vehicles could provide mobility for 12-15 percent of the population that does not drive.

Q—Would this technology be hacked?

David Levinson: Security is being paid attention to. As with any technology, there will be a cat and mouse game of keeping ahead of the hackers.

Leili Fatehi: The more serious concern is privacy of data about where people go.

Fatehi spoke of other legal barriers, such as a California law that requires a driver and steering wheel in some vehicles. She said that insurance companies will spur changes, because of the lower risk parameters of driverless vehicles.