jevons paradox

Smart lights reduce congestion in Pittsburgh

Cameron Shelley — Tue, 18 Oct 2016 13:41:20 +0000

Smart lights reduce congestion in Pittsburgh Cameron Shelley Tue, 10/18/2016 - 09:41

An item in IEEE Spectrum by Prachi Patel notes the development of a smart traffic system in Pittsburgh. Called Surtrac, the system developed by CMU professor Stephen Smith uses Artificial Intelligence techniques to adapt traffic signals to current conditions.

Prof. Smith's research suggests that Surtrac has reduced trip times 25 percent and idling times by over 40 percent, a significant difference.

Although such a result may obtain in the short term, decreases in congestion may evaporate over time due to the phenomenon of induced demand. In brief, induced demand refers to an increase in consumption of a resource after its supply is increased.

A smart traffic management system that reduces congestion would be equivalent to widening the roadways. That is, reduced congestion would produce more empty pavement at any given time, just as a program of road construction would produce. Historically, road construction programs have proven ineffective in reducing congestion in the long run.

In effect, smart traffic management would fall prey to Jevons' Paradox.

There are more effective solutions, such as congestion pricing or even increased parking fees. However, such schemes are politically touchy since car-loving citizens tend to see them as craven cash grabs. This perception may be what killed former New York Mayor Bloomberg's plan to implement congestion pricing in that city.

The Mayor eventually opted for a smart traffic system, an approach that does not excite the same political problems.

In the final analysis, the popularity of smart traffic management systems may have much to do with their political rather than their engineering features.

In the meantime, you can learn how Swedes in Stockholm have learned to love, or live with, their congestion pricing scheme!

View "Jonas Eliasson: How to solve traffic jams" on YouTube

Traffic inefficiencies and technological change

Scott Campbell — Fri, 30 Sep 2016 16:27:30 +0000

Traffic inefficiencies and technological change Scott Campbell Fri, 09/30/2016 - 12:27

Technology is often linked to efficiency. As in, technology change or technological progress equals greater efficiency. In our courses we try to break students of that assumption, and consider cases where greater efficiency may be harmful or anti-progressive. One of our favourites is Jevon's Paradox, in which an improvement in efficiency can paradoxically lead to an increase in consumption of the resource.

But here's another example. In this case, traffic efficiency was reduced to make streets safer.

Rowena Avenue in Silver Lake was placed on a "road diet" in 2013, where the street was reduced to one lane of traffic in each direction to make space for bike lanes and to slow down cars. It definitely had its detractors, but a op-ed penned today by a pair of data scientists argues the road diet achieved its goal of making the street less hazardous for everyone.

Los Angeles Times

Although we might assume that making automobile traffic flow more efficiently (ie: faster) through a city is a good sign of progress, in this case a different type of progress was chosen: saving lives.

The decision to implement a "road diet" came about after a child walking on the road was killed by a car. Reducing the speed of traffic on the road would reduce the probabilty of further fatalities: "According to the American Automobile Association, the average risk of death for a pedestrian reaches 10% at an impact speed of 23 mph, 50% at 42 mph and 90% at 58 mph." Without really getting into whether reduced speed would reduce the likelihood of accidents, at least if one happened, the risk of death would be reduced.

And so, the street was put on a diet, and rebuilt with two lanes instead of four, and new bike lanes. Average speed decreased from 39mph to 35mph, and collisions and fatalities have decreased as well. The data also seem to show that the traffic volume remained the same, possibly countering the argument that drivers in a hurry will simply find a speedier cut-through detour on side streets. Fewer collisions, no observable impact on volume? That sounds like progress, even if it's less "efficient" in terms of speed.

It might also be described as an improvement in equal rights. An article by Sarah Schindler in the Yale Law Journal last year about architectural exclusion cited Nicholas Blomley, who described this problem as traffic logic: "the idea that planners and civil engineers prioritize the flow of pedestrians and traffic through a physical space, with a focus on civil engineering, rather than prioritizing equal access to a physical space for all, with a focus on civil rights."

In short, let this just be a reminder that efficiency is a just choice we can make with technological changes, not an assumption; other choices are possible.

Drones, crops and Jevons' Paradox

Cameron Shelley — Mon, 22 Aug 2016 14:20:52 +0000

Drones, crops and Jevons' Paradox Cameron Shelley Mon, 08/22/2016 - 10:20

Jevons' Paradox concerns how increases in efficiency can lead to increases—rather than decreases—in consumption of resources. Designers expend a great deal of brainpower and passion on increasing the efficiency of their designs. The goal is often to decrease consumption of a resource, as a way of improving overall sustainability. In brief, the reasoning is that if a given task can be completed with fewer resources, then those resources will be conserved.

British economist William Stanley Jevons argued that the reverse will happen. In a nutshell, he argued that by making consumption of some resource more efficient, the cost of consuming that resource would decrease, thus stimulating consumption of it. That is, consumption would go up. That is Jevons' Paradox.

When reading about how some new technology will increase the efficiency of something, and thus its sustainability, it is interesting to consider how Jevons' Paradox may arise and, perhaps, spoil the party.

It was in that light that I read an article about how commercial drones will increase the efficiency of agriculture. For example:

Felix Weber is a crop consultant who operates Ag Business & Crop in Palmerston, Ont., in Wellington County. He says images collected from UAV flights can save a farmer money and help reduce chemicals going into the soil.

He gives an example of wheat damaged over the winter. Rather than adding nitrogen to the entire field in trying to save the wheat, UAV analysis suggested targeting only certain areas of the field. That saved money and was more environmentally friendly.

"My recommendation was not to apply nitrogen where there wasn't enough wheat. That was a cost savings to the farmer and 80 per cent of nitrogen was added rather than 100 per cent."

In short, farmers can use drones to reduce the amount of pesticide and other stuff sprayed onto crops in order to achieve a given yield. That will reduce costs and the pollution load on the environment, both wins for sustainability. Also, the cost of food for consumers should then be reduced.

Jevons' Paradox would suggest that both pesticide and food consumption should rise as a result of this application of drones. How could that be?

If we assume that demand for farmland and food is fixed, then it is hard to see a problem. However, the point of the Paradox is that demand can be stimulated by increases in productivity of supply.

In the case of farmland, the ability to produce a bushel of wheat, say, at a lower cost could stimulate increases in the production of wheat. That might be accomplished by converting non-wheat acreage to wheat or by increasing the productivity of each acre already used to produce wheat. This might also stimulate the conversion of marginal land, e.g., forests, into farmland for wheat growing. Those new crops would need to be sprayed, thus driving an increase in the amount of pesticide applied to crops over the whole agricultural system.

In the case of food, the availability of cheaper food might stimulate consumption of it. Homer Simpson once said that he discovered a new meal between breakfast and brunch (brunchfest?). People, especially people with money, are very good at inventing new ways to eat or waste food. Who's to say that we won't find even more, especially when food prices decrease?

I do not know if adoption of drones in agriculture will have these effects. The agricultural system is too complex to warrant sweeping conclusions from a few musings. However, it is instructive to remember that the so-called efficiency strategy for increasing sustainability is not a slam dunk either.