Congratulations to Alireza Ermagun for successfully defending his dissertation: “Network Econometrics and Traffic Flow Analysis.” He will soon be off to do a post-doc.

From the simulation-based viewpoint, a 3 × 3 grid network and Nguyen-Dupuis network are designed and adopted as main test networks along with several toy networks for pedagogical purposes. To simulate traffic flow, a macroscopic traffic flow model is selected due to the purpose of this dissertation, which deals with traffic flow in a link in a specific time slice and does not include the single vehicle-driver units. From the real-word viewpoint, a grid-like sub-network is selected from the Minneapolis – St. Paul highway system, which comprises 687 detectors and 295 traffic links. The traffic flow of each link is extracted in 30 seconds increments for 2015 as the most recent year.

The results of the analysis lead to a clear and unshakable conclusion that traditional spatial weight matrices are unable to capture the realistic spatial dependency 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 measuring the spatial dependence between traffic links. Neglecting these elements is not simply information loss. It has nontrivial impacts on the outcomes of research and policy decisions. However, using the proposed network weight matrices as a substitute for traditional spatial weight matrices exhibit the capability to overcome these deficiencies. The network weight matrices are theoretically defensible in account of acknowledging traffic theory. As the elements of the network weight matrix more closely reflect the dependence structure of the traffic links, the weight matrix becomes more accurate and defensible. They capture the competitive and complementary nature of links and embed additional network dynamics such as cost of links and demand configuration.

Building on real-world data analysis, the results contribute inexorably to the conclusion that in a network comprising links in parallel and series, both negative and positive correlation showe up between links. The strength of the correlation varies by time-of- day and day-of-week. Strong negative correlations are observed in rush hours, when congestion affects travel behavior. This correlation occurs mostly in parallel links, and in far upstream links where travelers receive information about congestion (for instance from media, variable message signs, or personal observations of propagating shockwaves) and are able to switch to substitute paths. Irrespective of time-of-day and day-of-week, a strong positive correlation is observed between upstream and downstream sections. This correlation is stronger in uncongested regimes, as traffic flow passes through the consecutive links in a shorter time and there is no congestion effect to shift or stall traffic.

I know what you are thinking, a Presidential nominee of a once serious political party has proposed to build a wall on the border with a foreign country, and “make them pay for it“. This sounds absurd. It is. It won’t happen.

Yet there is infrastructure we can have with no money down. We can get new infrastructure and “make” foreign countries pay for it.

I speak, of course of toll roads. Foreign countries, and private firms from foreign countries, have shown interest in building US infrastructure. Reason Foundation’s Annual Privatization Report identifies 31 large highway concessions, 20 of which were funded by tolls. The vast majority had international financial participation, and the whole amount was worth over $38 Billion.

Really, what could be better? No need to raise domestic taxes. Someone else builds a road or rail line or airport terminal or port we want and have already approved. If we break off diplomatic relations with their home country, they can’t roll up the infrastructure and take it home. If they go bankrupt (a not uncommon proposition), the facility stays and keeps operating. If we switch to flying cars, and their investment is stranded, they are on the hook for all the future losses. All we have to do is pay for the use of the public works while we use it, which we should be doing anyway.

The history of transport is very much the history of “foreign” investors building infrastructure “overseas” in developing countries. Just look at the history of US infrastructure financing in the 19th century, and you will see much international participation (e.g. the Erie Canal). The US has similarly developed infrastructure elsewhere in the developing world. If the rest of the world believes the expected rate of return in the US is higher than elsewhere, we should not disabuse them of that notion.

America has many dysfunctions, our collective inability to properly finance, price, and manage infrastructure is one I pay a lot of attention to. It’s not going to get substantially better any time soon (the next decade or so). There are many reasons for this, which have been discussed on the blog before.

Neil Stephenson wrote nearly 25 years ago in Snow Crash:

When it gets down to it — talking trade balances here — once we’ve brain-drained all our technology into other countries, once things have evened out, they’re making cars in Bolivia and microwave ovens in Tadzhikistan and selling them here — once our edge in natural resources has been made irrelevant by giant Hong Kong ships and dirigibles that can ship North Dakota all the way to New Zealand for a nickel — once the Invisible Hand has taken away all those historical inequities and smeared them out into a broad global layer of what a Pakistani brickmaker would consider to be prosperity — y’know what? There’s only four things we do better than anyone else:
music
movies
microcode (software)
high-speed pizza delivery

So if we can supply the world with software and pizza delivery (in the immortal words of Neil Stephenson), and they supply us with roads, the Law of Comparative Advantage suggests we are all better off.

All of which reminds me of the Simpson’s episode Radioactive Man, in which a movie is made in Springfield, and the locals take Hollywood for all its worth:

Jiminy jillickers! – We’re shutting down production.

– Yeah, well, we only have $1,000 left anyway.

Ah, there’s a $1,000 “leaving town” tax.

I hope you’re all satisfied.
You bankrupted a bunch of naive movie folks.
Folks from a Hollywood where values are different.
They weren’t thinking about the money.
They just wanted to tell a story.
A story about a radioactive man and you slick small-towners took ’em for all they were worth.

Should we give them some of their money back?

No.

Rebecca Beitsch at Stateline (republished at PBS Newshour) wrote Worsening highway traffic slows down paid express lanes. I get quoted:

…

What Are They Paying For?
As tolls have climbed around the country, researchers have noticed an interesting phenomenon: Rather than deterring drivers, as they are supposed to, higher prices tend to attract them.

David Levinson, a researcher at the University of Minnesota, said that when express tolls rise, many drivers take it as a sign that regular lanes are congested, rather than realizing that it means that the express lanes are especially crowded.

Levinson said people aren’t good at estimating how much time they’re saving by taking the express lane, and assume they are saving a lot because they are passing other cars. In fact, they may end up paying a high price for just a few minutes.

Even so, Levinson views the overwhelming popularity of express lanes as a positive development.

“If people are willingly paying lots of money voluntarily for this service it must be a valuable service,” he said. “That’s a success not a failure.”

The paper referred to is:

• Janson, M. and D. Levinson (2014) HOT or Not: Driver Elasticity to Price on the MnPASS HOT Lanes. Research in Transport Economics 44  21-32. [doi]

Who wants to review a book about Designing Transport? Email me your interest and I’ll send you the link to a review copy, along with reviewer instructions. You’ll be acknowledged in the book for your review. Reviews needed by end of September.