Lately I have been traveling to different states on weekly basis due to my work and interviews with other companies as I wrap up my college education. The traveling made me realize that each state has its pros and cons. From the beautiful Disneyworld in Florida to the Rocky Mountains in Colorado one thing became evident as I made conversations with locals, California is known for high taxes and traffic. The latter grabbed my attention as I often come across projects that seek ways to mitigate issues related to traffic. Currently I work in Santa Monica and my commute is perhaps one of the worst highlights of my job. The distance is only 11 miles however it takes me around 50 min to 1 hour to get to work (that’s an average speed of 12-13 mph). In addition, I am sure anyone living in Los Angeles can relate to the occasional heavy traffic at 1am on a normal weekend. The issue is a little complex and it goes beyond planning and traffic engineering. So what’s going on?
As a kid, I often wondered why the state build more lanes on the freeway or make double decker freeways (see picture below) to mitigate the demand of cars. But after some classes in traffic management, and transportation engineering I understood the concept that building more lanes only causes more traffic. In recent years traffic engineers understood that you can’t build your way out of congestion because studies show that the road themselves are what cause more traffic.
The economist Matthew Turner of the University of Toronto and Gilles Duranton of the University of Pennsylvania took a closer look at this phenomenon. The concept they used is called “induced demand” which is the way economist think when a product is delivered (in this case the roads) makes the end user to want to use it even more. Although research has been made before it was not until recent years that people collected enough data to make a plausible conclusion. This shows that the development of new roads are ineffective because the irrationality of the population when it comes to trying to avoid traffic in a highly congested city.
What the economist decided to do was to compare the amount of new roads and highways built in different U.S. cities between 1980 and 2000, and the total number of miles driven in those cities over the same period.
“We found that there’s this perfect one-to-one relationship,” said Turner.
The studies showed that if road capacities increased by X amount then the amount of driving also increased by X amount. Although the results are rather shocking the data is consistent along the whole study.
"As you add roads to a city those roads get filled up. There are people waiting to use that capacity. The result on transit is almost exactly the opposite of that." Turner added.
It could be that traffic engineers are building the roads based on the need of the community and their predicted traffic model fits perfectly with current traffic but Turner and Duranton thinks that it is highly unlikely. Their argument is based on the fact that the modern interstate network are closely related to the original plan developed by the federal government in 1947 and it is hard to believe that the engineers at the time could predict traffic behavior half a century in the future.
The study also took a look at public transportation and the results were alike. More trains, buses, troll systems, etc. created more users but that didn’t seem to relieve the traffic problem. I always thought of fluid dynamics as a model for traffics. In fluid dynamics you expect that by replacing a smaller pipe with a bigger pipe the pressure of the flow will drop causing a better flow. However, this is not the case for traffic, when you replace current roads with wider roads the traffic remains the same. It makes me wonder, where are this new drivers coming from? Were they included in the previous system before the widening of the roads?
According to a wired.com it has to do with what new roads allow people to do: to be able to move around. If you enable the possibility of driving more, they will do it more, causing to have more people willing to move farther away from work and therefore being forced to drive into town. It also means that if the widening of the streets causes an easier drive then it is more likely that drivers will jump in the car more often. Additionally, if there is more incoming traffic, businesses tend to develop faster which create extra traffic. The author argues that as long as the road remain cheap and accessible, people tend to overuse roads.
Interestingly, the study also showed that the phenomenon seems to work in reverse too. That is, when lanes are closed, population expects traffic to become much more chaotic. But the data shows that nothing too terrible occurs, that traffic readjust itself and congestion remains relatively constant.
So is this a never ending circle? Can we actually reduce traffic? Turner thinks that traffic congestion could be solved if the right policies are formed and enforced. According to Turner we use our roads system ineffective because we have a central authority setting the standards and prices for our public transportation. In other worlds we all obtain what we want: roads, and we get charged next to nothing. So is he suggesting a privatization of all roads? What Turner and Duranton suggest is what they call congestion pricing.
That means raising fees when the traffic demand is high and lower fees or make it free when traffic is low. In Los Angeles there are many freeways that already include this systems but it would be interesting to see whether or not it would have a drastic effect when applied to all roads across Los Angeles. The challenge with that is that voters don’t tend to pass these plans because it is hard to accept to pay for something that used to be free.
They also think that if congestion pricing is not doable, then cities should look into mitigating that traffic by surcharging parking fees in order to make the community more cognizant of parking.
“Because it’s free, people will misuse it and it will be full all the time,” said Duranton. Drivers searching for parking contribute significantly to road congestion. “There are some estimates that say in the central part of cities up to 30 percent of driving is people just cruising around for parking,” Duranton said.
It seems to me that their studies pose solutions that are targeted to increasing prices and start charging for the usage of roads. Whether it works or not, I would like to think that there is a better way to mitigate traffic. After all that’s the job of engineers, to find and create solutions to problems in a way that does not affect current conditions and that it’s also maximize the resources available.
The question is whether a small fee will make a big impact and If that’s the only option that mitigates traffic.
Next time you are sitting in traffic, don’t judge “the jerk” in front of you who just cut you off but the current conditions of our transportation system.