How closing streets and removing traffic lights can improve the pace of urban travel
by Linda Baker
Standard traffic engineering assumes that if the number of vehicles is constant, adding roads will reduce traffic congestion. So when Seoul city planners demolished a six-lane highway a few years ago and replaced it with an eight-kilometer-long park, transportation experts were surprised to find that the flow of transportation in the city improved, not deteriorated. "People went crazy," recalls Anna Nagorny, a researcher at the University of Massachusetts at Amherst who deals with computer networks and transportation. "It was like the opposite of the Braess paradox."
This paradox, the brainchild of mathematician Dietrich Brass of the Ruhr University in Bochum, Germany, is formulated as an abstraction: it states that in a network where all moving entities rationally seek the most efficient path, adding capacity may actually reduce the overall efficiency of the network. The project in Seoul proved this dynamic: closing the freeway - that is, reducing the capacity of the network - improved the efficiency of the system.
Although the Brass Paradox was first identified in the 60s, and is based on economic theory from the 20s, it never received much attention in the car-friendly United States. However, in the 21st century, the economic and environmental problems lead to a re-examination of the idea according to which limiting the travel space of vehicles may actually make the movement of more people more efficient. The key to this counterintuitive approach to traffic planning lies in influencing the inherent self-interest of all drivers.
A representative case is described in the article "The price of anarchy in traffic networks", published in September 2008 by Michael Gastner, a computer science expert from the Santa Fe Institute, and his colleagues in the journal Physical Review Letters. Using hypothetical and real road networks, they explain that drivers looking for the shortest route to their destination eventually reach a situation known in game theory as a "Nash equilibrium". In this situation no single driver can improve his situation by unilaterally adopting a different strategy. The problem is that the Nash equilibrium is less efficient than the equilibrium that would be created if the drivers acted unselfishly - that is, if they adjusted their actions to the common good.
"The price of anarchy" is a measure of the inefficiency caused by selfish drivers. In the analysis of transportation between two places in Boston, the researchers discovered that this price may be high: selfish drivers spend 30% more time on the road than would be required under "socially optimal" conditions.
Gastner says the solution rests on the Brass Paradox. "Since selfish drivers bring the incorrect function to its optimal value, we can direct them to a better solution if we remove some of the connections in the network," he explains. why? To some extent this is because road closures make it difficult for individual drivers to choose the best (and selfish) route. In the Boston example, Gastner's team discovered six sites where traffic could be blocked and delay reduced in the selfish driving scenario (these roads would not slow down drivers if they were behaving unselfishly).
Another kind of anarchy may actually accelerate the movement. This is a counter-intuitive traffic planning strategy known as "shared streets". This method encourages driver anarchy by eliminating traffic lights, markings on the road and boundaries between the road and the sidewalk. Studies done in Northern Europe, where shared streets are common, show an improvement in safety and traffic flow.
The idea is that the absence of traffic regulation forces the drivers to show more responsibility for their actions. "The less comfortable the driver feels, the more he is forced to make eye contact with pedestrians and other drivers on the street, and naturally slow down," explains Chris Conway, a city engineer from Montgomery, Alabama. In April 2008, the city replaced a signalized intersection with a common European "Dutch Street" for pedestrians, bicycles and cars - one of several similar projects popping up across America.
Apparently, encouraging traffic chaos contradicts the ideas presented in the "The Price of Anarchy" study, but in fact both strategies reduce the importance of the single driver in favor of the improved overall results. They also offer a larger traffic niche for bicycles and pedestrians. In light of the fact that the Obama administration is preparing to invest in the largest public construction project since the establishment of the American highway system (the "Interstate"), the idea of few and inclusive roads now seems more relevant than ever.
Fast streets with less parking
New parking management strategies can also improve the flow of urban transportation. Says Patrick Zigman, a senior at the San Francisco-based Nelson/Nygaard consulting company, which deals with traffic planning. In the 50s, in a misguided attempt to reduce traffic congestion, urban planners required contractors to provide a minimum number of free parking spaces - a strategy that "completely ignored" basic economic principles, says Sigman, referring to how low prices increase demand.
Today, limited urban space and fear of global warming are causing city planners to cancel these requirements. In San Francisco, for example, the contractors must limit the parking space to a maximum of 7% of the surface of a building - a very negligible amount. Although employment within the city has increased, says Sigman, traffic congestion has actually decreased. When there are no free parking spaces, drivers switch to other methods and rely more on public transport, bicycles and even simple walking.
Linda Baker writes from Portland, Oregon.
17 תגובות
Point, instead of looking at just a point look at the whole image/space.
When there is one "best" route, everyone will strive to reach only it and create a load and a bottleneck effect on it, while ignoring other slightly less good routes, which remain free.
When there are several "slightly less good" lanes, the load will be shared between them and paradoxically, apparently, the utilization of the overall road system will be greater.
It reminds me exactly of the signs pointing to the Hutzav Israel road from everywhere - even in far away places like the Gilolit junction! It's as if the cross-Israel road has become a destination in itself... and this is completely against the role of a road, which is to be a means to reach a destination, not a destination in itself.
So perhaps the paradox is in the current distorted way of thinking and when you free yourself from it - you return to a correct and natural method.
Adding lanes to a bottleneck increases the load at the entrance. On the other hand, the narrow opening regulates the flow. What does this mean in simple terms? that if there is a big traffic jam at the entrance to an urban lane, the traffic may flow nicely in the narrow lane and the traffic, the slowness, the wastage of fuel and everything you want remains outside. This traffic jam is the big profit of the owners of the fuel companies, the government (the people inside the government) and that's why this kind of article comes. And another statement of the same type, when Egypt opens an exit, the flow speed increases at the same pressure, but the power? And that's what we pay for
Brass's paradox
Can anyone refer to a book or article on the Brass paradox?
To Michael:
There is no claim in the original response (response 5) regarding the manner in which the article was written, it is written properly, and one should not see the shadow of mountains as mountains...
Your idea about breaking into a closed door is interesting. There is no doubt that sometimes it is necessary to go through a closed door, no matter what. Allow me, for the sake of humor (only!!!), to suggest that a closed door can be dealt with in several other ways besides 'outburst', bearing in mind that the outburst may lead to the breaking of the door and/or the breaking of the arm and/or a lawsuit for damages and/or Indictment for damage to property/body, trespassing, causing a nuisance, etc. It is better to negotiate with the landlord first, and in any case check before the act if the door is locked and if it can be opened with a slight turn of the handle...
I of course accept the last sentence in your response. I wish only good, and happy holidays.
Eddie:
I'm sorry but I wasn't convinced.
I see your words in the original response as a claim against the way the article was written and in my opinion (which I reasoned in my response) this is a claim that is not justified because the article is worded exactly the way it should be worded so that they understand that it is not something that always happens but something that happens sometimes.
That's why in my opinion - your words are still an attack on an open door.
By the way - just as bursting into an open door is unnecessary, bursting into a closed door is also necessary if you want to move to the other side.
It is not advisable to close the door to factual comments and my comment was for your words and not for anything else related to you, therefore describing it as a comment about a person's body is not justified.
To Michael in response 6:
Your above response is, how to say, not on the conceptual level, but on the legal level, and not so much to the substance of the matter as to the substance of the man.
The article does not present examples that constitute an exception to the abstraction (it does not talk about the abstraction applying to 'certain cases' only, nor does it characterize certain such cases. On the contrary, the article is even about a 'representative case') and does not point to the existence of any principled caveat to the abstraction. According to the simplicity of the wording regarding the paradox, it was possible to understand that 'in fact' indeed the paradox in the end - works, despite what common sense dictates. The word 'may' can be understood in this context not necessarily as indicating the existence of any caveat to abstraction (since such a caveat is not hinted at in the article) but only as indicating a seemingly surprising but positive causal relationship between capacity reduction and system efficiency.
That's why I saw to comment in my response 5 as I commented, and there was no 'outbreak' nor 'open door' here.
With all due respect - which you deserve - I am commenting that your reaction was an 'outburst', and the door is closed. You should be less explosive and more matter-of-fact (and we all know that you know how to be like that too, and usually do it quite well).
Happy Independence Day everyone.
point:
This is not the case I described.
City C is a central city and since it is only a city, and therefore located in a limited geographical area, the entrances to it must drain and meet.
When the roads were built, the traffic load was lower and even a traffic light was not necessary.
In those days, everyone praised and praised the one who dressed the country in concrete and cement and built roads from everywhere to everywhere.
In many days the traffic in that country increased and the problem I described arose.
Look, I certainly didn't mean to claim that a road engineer can't design such a road that will cause traffic jams, for example by complicated intersections that will create a lock.
Therefore, an early and reasonable assumption is that the roads were designed so that they would not destroy existing infrastructures but would add to them. Then it is clear that it is not possible that closing a road will benefit transportation.
But if someone planned a road that would destroy the traffic on the existing roads, then of course in this situation road closures would benefit transportation. In addition to the layoffs he plans.
point:
No. I'm not necessarily talking about canceling the traffic lights because, as I mentioned - if they canceled the traffic lights there would be a traffic jam and war, which also cause inefficiency in the use of the road.
We are all aware of what happens (especially in Israel) when a certain traffic light stops working.
After all, usually not much time passes from the moment the traffic light ceases to operate until the complete cessation of traffic at the intersection.
I'm talking about the advantage of significantly reducing the time lost in coordinating the two routes (whether through traffic lights or through wars).
Michael, are you talking about the advantage created as a result of canceling the traffic light?
Because then it is no longer related to what I was talking about.
Eddie:
As soon as you use a phrase like "may actually reduce the slowness of efficiency" then you qualify things in advance and therefore your comment bursts into an open door.
After all, in advance no one claimed that the efficiency would always decrease, but only in certain cases.
Bras Shobaino paradox doesn't sound so paradoxical, after a second and third thought.
But I wonder how far the abstraction "in a network where all moving entities rationally seek the most efficient path, adding capacity may actually reduce the overall efficiency of the network" can be applied and how applicable it is to socio-economic systems. For example: Will blocking certain courses of study at the university increase the socio-economic efficiency? It is possible, for example, to imagine that we could, in the above-mentioned respects, manage better without the massive groups of jurists that the higher education system produces every year (people who pay attention to their quantity - the relative productive return of their education to the economy, and considering the investment involved in imparting their education in terms of time and money, is low example of engineering students, for example). It is possible that the socio-economic-occupational system is losing from the aforementioned excess educational capacity. On the other hand - in the long term, excessive obstruction stifles mobility, growth and creativity, in a way that ultimately causes the degeneration and petrification of the system (this may be true not only for a social system, but also for simpler systems, such as a traffic system - if the abstraction is applied to it, it loses its Its flexibility and it is possible that in the wider range we are losing our innovation and opportunities for necessary development in light of changing circumstances).
point:
It is not appropriate for you to argue with facts nor with claims that can be proven mathematically.
Describe to you, for example, a situation where there are roads between cities A, B, and C.
Imagine that near the end of the road the road from A to C merges with the road from B to C and at the point of union there is a traffic light that alternately gives priority to those coming from A and B (or alternatively, a permanent traffic jam where everyone is pushed, gets stuck and wants to kill each other) .
Also imagine that all the residents of A and B work in C.
Let's also assume that A, and B are close to each other and far from C (perhaps we will exaggerate further and say that B is on the aerial line that connects A with C and that the road from A to C bypasses B)
Is it difficult for you, under these conditions, to describe a situation where everything would flow better if they canceled the direct road from A to C and required the residents of A to enter B on their way to C?
Someone is cheating. If you close a main road and the number of vehicles in the area remains the same, then the load will increase. There is no paradox.
Joseph:
exactly.
And the one who starts the car also doesn't start it. It just activates some small electric motor that may later start it.
Even the fact that I write these things does not harm you. Just reading them might hurt you.
A tiny quirk: demand is a function of prices. Therefore, low prices (ie increasing supply) change the equilibrium point, and do not "increase demand".
Thanks, sorry, and goodbye.