Political Economy at Any Speed: What Determines Traffic Citations?

Via Peter Gordon, from New York Times: Welcome, Stranger. Here’s a Speeding Ticket.
… ” Michael D. Makowsky, a doctoral student in economics, and Thomas Stratmann, an economics professor, both at George Mason University, studied the issue in a recent paper, ”Political Economy at Any Speed: What Determines Traffic Citations?”
They examined every warning and citation written by police officers in all of Massachusetts, excluding Boston, during a two-month period in 2001 — over 60,000 in all. Their conclusion wasn’t shocking to an economist: money matters, even in traffic violations. They found a statistical link between a town’s finances and the likelihood that its police officers would issue a speeding ticket. The details are a little sticky, but they show that tickets were issued more often in places that were short on cash, and that out-of-towners received tickets more often than drivers with local addresses.” …
(original paper by Makowsky and Stratmann available here)
So this paper provides some more evidence of tax exporting in transportation finance, a favorite topic of mine since my dissertation “On Whom The Toll Falls”, extended in the book Financing Transportation Networks
More importantly, it is one less paper I have to write, it has on been my ‘to do’ list since my dissertation, but I never had the time to get together the data.
One could extend this work by looking at the location of “speed traps”, where the hypothesis would be these are at the edge of town, and thus more likely to nab out-of-town drivers than in the middle of town (assuming imports=exports, and no through trips, 50% of all travelers at the edge of town are from out-of-town, a smaller percentage of travelers inside town are out-of-town; if there are through trips, then more than 50% of travelers at the edge are non-resident, while again a smaller number of internal trips are non-resident).

Garrison: Increasing the Flexibility of Legacy Systems

Bill Garrison gave the 2007 Anderson Distinguished Lecture in Applied Geography, in which he gave a talk on “Increasing the Flexibility of Legacy Systems”, a topic dear to his heart. The proceedings, excellently prepared, also provide some background on Garrison, and the Legacy has provided, both to Geography and Transportation.
Well worth the read if you feel transportation is stuck, and no real progress is being made.
— dml

Canada’s Crumbling Infrastructure

From CBC (via Zvi) Montreal mayor wants inspection reports for private buildings. It seems our neighbor to the north has crumbling infrastructure too. This is somehow reassuring (if it can happen to Canada it can happen anywhere, so it’s not anything “we” did or didn’t do), on the other hand it suggests there is no easy example to point to, if only we did like “so and so” we wouldn’t have these problems.
Awareness of crumbling infrastructure is like a virus (whether the infrastructure itself is crumbling because of some contagion would be an interesting scientific hypothesis, but doubtful).

I-35W bridge collapse – What happened on August 1st and after

One of the interesting scientific questions that emerges from the tragedy of the I-35W Bridge Collapse is how traffic responds. There are several time horizons for looking at this.
Most immediately are those who are on the link leading up to the bridge. MnDOT’s traffic cameras show the cars turning around on the freeway within seconds of the bridge collapsing, before the dust clears literally. “Video footage of the collapse from Mn/DOT traffic camera 628. 6:05 p.m., Aug. 1, shows an edited two-minute clip from a traffic camera at the south end of the bridge. Initially, the camera is pointed to the south away from the bridge. When traffic comes to a stop, the camera pans to the north where the bridge has just collapsed. (wv file)”. This is a rational response on the part of drivers who don’t know what else may collapse. As my wife says, there are two types of people “those who run towards the meteorite and those who run from it”. Survivors are those who ran from it.
Over the next few minutes and hours, word of the bridge collapse spread. My student Shanjiang Zhu has organized MnDOT’s loop detector data into a movie that shows the 15 minute traffic counts on all the loop detectors in the Twin Cities, comparing that number with the previous Wednesday’s count at the same time of day. Blue indicates lower volumes, red higher volumes. Clearly after the collapse, people heard quickly through various sources (cell phone, variable message signs, radio, etc.), and avoided large swaths of I-35W in the vicinity (which turns blue) and complementary feeder links, while competititve substitute links (Mn 100, I 35E, parts of I-94) saw an increase. We still have to compute how overall traffic volume and Vehicle Kilometers Traveled changed.
Once people were informed, on subsequent days people searched for alternatives. The alternative the first day for some was to avoid driving, but that quickly changed, and different routes became natural substitutes. A second movie compares the counts on the 15 days after the collapse with the average of the previous 8 weeks same day of week (so a Thursday is compared with the eight pre-collapse Thursdays). This illustrates the changes network wide. The
movie is available.
Finally, there may be some longer term adaptations, but we don’t have enough information only one month into the changed situation to know about this yet. With colleagues Henry Liu and Kathleen Harder, we have obtained a National Science Foundation Small Grant for Exploratory Research to look at all of these issues in some more depth.


Prior to leaving for London we sold our second car to cash up for the trip. On return, we had two children, two drivers and one car. As I usually walk to work, this is normally fine, but on occassion one has offsite meetings. For this Zipcar and other car sharing programs offer an alternative. Having read the literature on this, and being skeptical, I still signed up to test it.
Zipcar has several locations on campus at the University of Minnesota where they keep cars. For a fixed fee, I get the opportunity to rent cars from Zipcar with a minimum of paperwork and contracts. I can reserve the car online (assuming it is available, which may turn into a problem if demand is high) and then can rent the car for $8 per hour plus tax. This sounds expensive, and requires planning, but in exchange I avoid all the fixed costs of auto ownership.
I am issued a Zipcard, which I swipe over the keyhole on the car I reserved, and electromagically, the car door unlocks. The key is in the car. I am responsible for fueling, parking etc., but presumably Zipcar takes care of maintenance and insurance.
Using the car yesterday went quite smoothly once I figured out the operation of the Zipcard in unlocking the door (it sounds obvious, but isn’t quite, and didn’t work immediately, though did a second time), and getting out of the garage (which requires the use of the parking garage contract card, which is in the car, but is again not obvious if you have not done so before.
Otherwise, the car was where it was supposed to be, ran fine, and I have had no problems with the experience.
The only problem I foresee is if demand outstrips supply, renting on-demand may become difficult. Zipcar could add vehicles to the fleet, but there may be some lag on this. However, like many network industries, the more members, the more valuable, as it will then be available in more places, and my likelihood of getting a car when and where I want will be easier.

a blog about Networks and Places


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